- Email: [email protected]
Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation
Accepted Manuscript Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation Joachim M. Oertel, M.D, Benedikt W. Burkhardt, M.D. PII:
S1878-8750(17)30455-2
DOI:
10.1016/j.wneu.2017.03.132
Reference:
WNEU 5501
To appear in:
World Neurosurgery
Received Date: 10 November 2016 Revised Date:
27 March 2017
Accepted Date: 28 March 2017
Please cite this article as: Oertel JM, Burkhardt BW, Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.03.132. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation
Joachim M. Oertel, M.D. and Benedikt W. Burkhardt, M.D.
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Corresponding author Prof. Dr. Joachim M. Oertel Klinik für Neurochirurgie Kirrbergerstraße 100 66421, Homburg-Saar Germany Phone: +49-6841-1624400 Fax: +49-6841-1624480 Email: [email protected]
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Department of Neurosurgery, Saarland University Medical Center and Saarland University Faculty of Medicine, Homburg-Saar, Germany
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Background
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Almost every surgical approach carries the risk to cause some degree of spinal instability,
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especially in case of excessive resection of the lamina and facet joint. This study describes the
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endoscopic intralaminar approach (ILA) for the treatment of cranially and caudally migrated
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lumbar disc herniation.
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Methods
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Thirty-one patients who underwent endoscopic ILA for 26 caudally and 5 cranially migrated
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lumbar disc herniation were identified from a prospectively database. At final follow-up a
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personal examination and a standardized questionnaire was conducted including Oswestry
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Disability Index (ODI), functional outcome according to modified MacNab Criteria.
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Additionally particular reference was given to back-pain, leg-pain and repeat procedure.
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Results
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The mean final follow-up was 37.0 month (range 5-57 month) at which 29 patients attended
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(93.5%). No leg pain was noted in 95.0%, no back pain in 85.0%, full motor strength in
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95.0%, and no sensory deficit in 95.0% of patients with ILA. Clinical success was reported by
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95.0% of patients and the mean ODI was 9% in patients with ILA. Ten patients had an
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enlargement of ILA to conventional laminotomy (32.3%). By comparison of clinical outcome
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and repeat procedure rate in patients with ILA to patients with enlargement to laminotomy no
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significant differences were identified except for higher ODI (i.e.16%) in patients with
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enlargement of ILA.
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Conclusion
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Endoscopic ILA is a safe technique for the treatment of cranially and caudally migrated
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lumbar disc herniations. Careful procedure planning is recommended to protection of soft
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tissue and osseous structures and to achieve excellent clinical outcome.
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Lumbar disc herniation is a common degenerative disease in the western countries. In 1971
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Macnab described the term “hidden zone” for migrated disc herniations.1 According to
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Macnab the lateral zone of the spinal canal can be divided into three sections, including the
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subarticular zone, the foraminal zone, and the extraforaminal zone. A disc herniation that is
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located between the medial and lateral margin of the two adjacent pedicles it is considered to
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be in the foraminal zone.1 2 A disc herniation that is located laterally to a line of the lateral
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margin of the two adjacent pedicles is considered to be extraforaminal or far lateral. Other
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authors used the term “preforaminal zone” instead of “hidden zone“ to describe this particular
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localization.3 If the disc herniation occurs at the “preforaminal zone” or “hidden zone” the
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surgical approach might be associated with difficulties.2
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Caspar et al first described the microsurgical interlaminar approach which might be unsuitable
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for pathologies located in the “hidden zone” unless the approach is extended to a
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hemilaminectomy with partial or complete facetectomy for better exposure of the
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Neuroforamen. This extension might carry the risk of instability due to destruction. 4-6 An
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approach via lateral fenestration or posterolateral approach is less destructive and preserves
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the stability of the lumbar spine but offers poor exposure of the medial foraminal portion.2 7 In
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1998, Di Lorenzo et al. proposed treating foraminal and preforaminal lumbar disc herniation
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via a “pars interarticularis fenestration” by sparing the partial resection of the facet joint8.
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Soldner et al. described a similar but modified approach and called it “intralaminar approach”
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(ILA). However, the ILA describes by Soldner and Di Lorenzo was followed by tissue and
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muscle dissection. 8 9
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In the past decades tubular assisted surgery was introduced to spinal surgery to combine
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bimanual microsurgical technique with reduced the tissue and muscle trauma during the
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surgical approach. 10 Additionally since 2007 the HD-endoscopic visualization is available
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and allows for better illumination and tissue identification compared to previous standard
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definition. 11 12
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To the best of our knowledge this is the first report of a series of 29 patients with caudally and
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cranially migrated disc herniation who were operated via endoscopic ILA. The purpose of this
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study was to describe the surgical technique, clinical outcome, and feasibility of endoscopic
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ILA.
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Material and Methods
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Patient population
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Retrospectively, the surgical report and the endoscopic video recording of all patients who
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underwent endoscopic procedure for the treatment of lumbar disc herniation from January
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2011 to December 2015 were reviewed. Only patients in whom the surgeon had the intention
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to resect a migrated lumbar disc herniation via an endoscopic ILA were selected for further
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clinical and radiological evaluation. Evaluation included the review of preoperative and
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postoperative patient record, evaluation of endoscopic video recording as well as the
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evaluation of the preoperative MRI scan. The localization of the disc herniation was defined
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according to the classification of Ikuta et al. (Figure 1) 13. The endoscopic video recording
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was reviewed to analyze the diameter of the intralaminar approach and whether an
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enlargement of the ILA was performed. The authors defined the enlargement of the ILA to a
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conventional laminotomy as follows: once a portion of the superior or inferior edge of the
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lamina was not intact (e.g. thinned out by diamond drilling or resected via a Kerrsion punch).
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At final follow-up a physical examination and a standardized questionnaire were conducted.
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The questionnaire included the Oswestry Disability Index (ODI) 14, functional outcome
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according to modified MacNab Criteria (Table 1). Clinical success was defined as excellent
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and good result according to MacNab criteria.
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Surgical equipment
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All procedures were performed with the EasyGO® spine system. The endoscopic equipment
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consisted of a 30° Hopkins® Forward-Oblique telescopes with 9.5 cm in length, a H3-Z Full
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HD Camera Head and a Xenon Nova® 300 cold light fountain. The intraoperative image was
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transmitted on a 26" HD Flat Screen. All intraoperative data was recorded via AIDA®
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compact NEO data archiving system (KARL STORZ GmbH & Co. KG, Tuttlingen,
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Germany).
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Surgical technique
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Prior to surgery the preoperative lumbar MRI analyzed to plan the trajectory of the working
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trocar. The trajectory of the working trocar varies depending on the operated segment and
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might get very step, especially in caudally sequestrated disc herniation (Figure 2). The
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procedure is performed under general anesthesia, preoperative antibiosis is admitted. Patient
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is place central on the operating table in prone position. The neck is in neutral position, 4
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abdomen is decompressed on a Wilson frame and pressure points are padded and a C-arm for
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lateral fluoroscopy is installed. A spinal tap needle is used to identify the affected segment
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(Figure 3).
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The trajectory of the needle should be perpendicular to the disc herniation. Skin incision is
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about 2 cm paramedian of the spinous process and about 1.4 – 1.8 cm in length depending on
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the selected trocar After the muscle fascia is opened the smallest dilator is put in direct
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contact to the bony surface of the hemilamina under lateral fluoroscopic control. Soft tissue
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and muscles are be pushed away and dilated by sliding the various dilators one over the other.
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After tissue and paraspinal muscle dilation the working trocar is placed fixed in position via a
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holding arm. The three-chip high definition (HD) camera head is introduced and placed in
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correct position. The full-HD endoscopic unit is generally positioned on the other side of the
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operation table so the surgeon can also assume a more comfortable position while doing the
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surgery in bimanual technique (Figure 4). A preoperative MRI scan and the accompanying
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main steps of the ILA and sequestrectomy are shown on figure 5 and figure 6. A more
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detailed case is demonstrated on video 1.
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The authors performed a partial discectomy in cases of identification of a large annulus
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perforation. After sequestrectomy the working trocar is recommended to be removed under
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endoscopic control to detect and immediately treat bleeding source of the paraspinal muscle.
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The thoracolumbar fascia can be closed using 2.0 interrupted sutures. In obese patients it is
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recommended to adapt subcutaneous tissue followed by subcuticular suture. A skin adhesive
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allows the patient to shower on the first postoperative day.
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Statistical Analysis
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Statistics were calculated using SPSS version 23 (IBM, Armonk, NY, USA). The paired t-
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test, Mann Whitney test, Wilcoxon test, and Fisher exact test were used for analysis. Any P
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values were given two-sided. A P value of <0.05 was assumed to be sufficient to indicate
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statistical significance.
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Patient Demographics
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One hundred and forty-two patients underwent endoscopic procedure for lumbar disc
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herniation. In thirty-one patients (17 male and 14 female) the intention to perform an ILA for
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the resection of a migrated lumbar disc herniation was noted in the surgical report. According
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to the surgical report the surgeon choose an interlaminar approach in the remaining 111
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procedures due to localization and shape of the disc herniation or concurrent stenosis of the
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lateral recess. The mean age at endoscopic procedure was 52.1 years (range 31-82 years), the
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mean duration of symptoms prior to endoscopic procedure was 5.3 month according to the
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documentation in the file.
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The preoperative MRI scan and the endoscopic video recording revealed the diagnosis of a
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lumbar disc herniation in all cases.
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The primarily indication for endoscopic ILA was radicular pain resistant to conservative
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treatment, a motor deficit, or a sensory deficit. The L2 lamina was involved in one (3.2%), L3
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lamina in five (16.1%), L4 lamina in fourteen (45.2%), and L5 in eleven ILAs (35.5%).
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Preoperative MRI Evaluation
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The disc herniation was sequestrated caudally in 26 cases (83.9%), and in five cases it was
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sequestrated cranially to the disc level (16.1%).
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The analysis of the localization of the disc herniation revealed that it was sequestrated into the
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subarticular zone in 13 (41.9%), into the preforaminal zone in 2 (6.5%), into the foraminal
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zone in 1 (3.2%), into the subarticular and the preforaminal zone in 6 (19.4%), into the
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subarticular and foraminal zone in 3 (9.7%), into the preforaminal and foraminal zone in 3
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(9.7%), and into all three zones in 3 (9.7%) cases.
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Endoscopic Video Recording Evaluation
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The endoscopic video recording revealed a successfully performed endoscopic ILA in 21
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cases (67.7%) and an enlargement of the endoscopic ILA to a laminotomy in 10 cases
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(32.3%).
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A more detailed analysis of the ten cases with enlargement indicated that had pervious lumbar
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surgery at the adjacent level was performed in three cases. Therefore the feasibility to perform
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endoscopic ILA was compromised because the hemilamina in those three cases was partially
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resected and the surface was diminished prior to endoscopic ILA.
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In another three cases the ILA was enlarged after sequestrectomy for further decompression
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of the nerve root via foraminotomy.
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In two cases the ILA was enlarged for better exposure and resection of a subligamentous disc
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herniation. At last in two case the inferior edge of the hemilamina was incidentally drilled
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while ILA.
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Intraoperative Findings
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Mean overall operating time in all procedures was 54 minutes (range 25 – 85) minutes.
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Seventeen patients were operated via a 15mm and fourteen patients via a 19mm working trocar.
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In all cases, the disc herniation was identified and removed. Intraoperatively in 18 cases a
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perforation of the annulus was identified and consecutive partial discectomy was performed
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(58.1%).
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No emergency stopping with switching to microsurgery was required. The mean diameter was
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for ILA was 7 mm (range 5-9 mm). The diameter was measure as the ratio of the outer
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diameter of the suction tube to the actual ILA.
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In two cases a dural tear occurred which was closed endoscopically with a combination of an
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autologous muscle patch and a collagen sponge coated with the human coagulation factors
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fibrinogen and thrombin. None of the two patients reported any kind of discomfort which
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could be related to the CSF leak or pseudomeningocele.
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Clinical Findings: Preoperative, Postoperative & Final Follow-up
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At final follow-up 29 out of 31 patients (17 male and 12 female) attended the physical
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examination and standardized questionnaire at our Neurosurgical Department (93.5%). The
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mean follow-up time was 37.0 month (range 5-57 month).
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Preoperatively 27 patients had radicular pain (93.1%), fifteen patients had a motor deficit
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(51.7%), and eleven patients had a sensory disturbance (37.9%). The mean leg pain intensity
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on the NPRS was 7 (range: 0 – 10), the mean back pain intensity on the NPRS was 6 (range: 0
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– 10).
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Four patients had a history of chronic back pain prior to their onset of a new radicular
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disturbance. One patient had a paresis and sensory deficit since over 30 years due to previous
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lumbar disc surgery.
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Postoperatively all patients were mobilized at the day of surgery. Twenty-six patients reported
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to be pain free or with improved leg pain (96.3%), thirteen patients reported an improvement
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in motor strength (86.7%), and eleven of patients reported an improvement of their
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preoperative sensory disturbance (100%). The mean leg pain intensity on the NRPS decreased
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to 1 (range: 0 -7), which was statistical significant (p< 0.001). The mean back pain intensity
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on the NRPS was decreased to 2 (range: 0 – 7), which was statistical significant (p< 0.001).
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No postoperative wound healing problems or wound infection were noted. One patient with a
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history of chronic low back pain underwent endoscopic procedure due new paresis. The
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paresis completely recovered but the patient reported n new onset on radicular pain. The
postoperative MRI and radiograph showed no signs of nerve root compression or instability.
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At final follow-up examination twenty-four patients reported to be free of leg pain (88.7%),
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one patients reported to have intermittent leg pain (3.4%), and two patients reported to have
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mild leg pain while physical activity (6.9%). None of the patients reported to take pain
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medication regularly. Twenty-three patients reported to have no back pain (79.3%), four
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patients reported to have back pain (13.8%). Among those four patients two patients had a
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history of chronic back pain and two patients underwent repeat procedure due to degenerative
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disorders after endoscopic procedure. Two patients reported to have low back pain while
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sports activity (6.9%). Among those two one patient had a history of chronic low back pain.
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Twenty-five patients had full motor strength (86.2%), in three patients a mild (4/5) residual
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paresis remained (10.3%), and in one patient the former documented paresis due to previous
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surgery remained the same (3.4%).
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Twenty-six patients had no sensory deficit (89.7%), one patient had a residual sensory deficit
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(3.4%), in one patient the former documented sensory deficit due to previous surgery
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remained the same (3.4%), and one patient reported a new onset of sensory disturbance
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(3.4%)
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According to the MacNab criteria 26 patients reported to have excellent or good results
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(89.7%). The mean ODI was 11.0% (range: 0% - 64%). The ODI ranged from 24% - 64%
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among patients with a history of low back pain. By excluding patients with a history of low
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back pain the mean ODI decreased to 5%. (range: 0% - 24%).
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An analysis of clinical outcome at final follow-up separated for patients with ILA only and
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patients with enlargement of ILA to conventional laminotomy is shown on table 2.
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Patients with repeat lumbar spine procedure: Among those patients with successfully
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performed ILA one patient reported a new onset of radicular pain on the seventh
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postoperative day and underwent repeat microsurgical discectomy for recurrent disc
4
herniation. The same patient was operated at the cranial adjacent segment due to another disc
5
herniation 17 month after the initial endoscopic surgery.
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Among those nine patients with an enlargement of ILA to conventional laminotomy three
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patients underwent repeat procedure. One patient had a recurrent disc herniation four month
8
after initial endoscopic procedure and underwent microsurgical discectomy. The same patient
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had a recurrent disc herniation with consecutive spondylolisthesis two years after initial
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surgery and underwent transforaminal lumbar interbody fusion (TLIF). Another patient with a
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history of chronic back pain underwent nerve root adhesiolysis and TLIF four month after
12
initial endoscopic procedure. At last one patient underwent repeat surgery for lateral recess
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stenosis at the contralateral side three years after initial surgery.
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Lost at follow-up
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Two patients were lost at follow-up. According to the files one patient had a new onset of
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radicular pain and a motor deficit 15 month after the initial endoscopic procedure. The MRI
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scan revealed a disc herniation at the index segment on the contralateral side and the patient
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underwent repeat microsurgical discectomy. According to the outpatient note an improvement
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of leg pain and motor deficit was documented. The second patient had an enlargement of ILA
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to conventional laminotomy. According to the outpatient note an improvement of leg pain
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was documented.
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The ideal approach for the treatment of cranially or caudally migrated lumbar disc herniations
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is still controversial. Migrated lumbar disc herniation can be exposed via an interlaminar
4
approach but extensive resection of the lamina might be necessary for exposure. Especially
5
bone removal at the pars interarticularis might lead to spinal instability and cause
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postoperative back pain. The direct approach by “fenestration of the pars interarticularis” was
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first described by Di Lorenzo. Critics eyed Di Lorenzo`s approach very skeptical. 8
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Shortly after the so called “intralaminar fenestration” was presented by Soldner el al. It was a
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modification of Di Lorenzo`s approach with preservation of the pars interarticularis. Good to
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excellent clinical outcome in 90% to 100% of cases and a recurrent disc herniation rate of 3%
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to 7% have been reported. 3 9 15
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In contrast to the present study the majority of studies reported about the treatment of
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cranially migrated disc herniations. Papavero et al. reported a series of 104 patients with a
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mean follow-up of 27 month who underwent ILA. It was stated that ILA is a safe surgical
15
technique for the removal of cranially migrated disc herniations. However, Papavero was of
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the opinion that the recurrent disc herniation rate of 7% was caused by the fact that
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discectomy was performed in only 15% of his series. 3 13 15 16 15
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In the present study a partial discectomy was performed in 58% of all cases, which might be
19
the reason for slightly lower recurrent disc herniation rate on the ipsilateral side was (i.e.
20
4.8%). However, the present study design is not suited to assess whether partial discectomy
21
should be performed to achieve lower recurrent disc herniation rate or not. Tubular assisted
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spine surgery is considered to be as effective as open microsurgical technique with the
23
advantage of less muscle and tissue trauma.
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Hussein evaluated the clinical outcome of 36 patients who underwent endoscopic tubular
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assisted interlaminar approach for the treatment of cranially migrated lumbar disc herniation.
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In his series with a two year follow-up the mean ODI was about 20% and three patients
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underwent repeat procedure due to no improvement or recurrence of radicular pain (n=2) and
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new mechanical low back pain (n=1). Interestingly the mean surgical time in the endoscopic
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groups was 85 minutes in therefore 30 minutes compared to our groups. This difference might
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be cause due to the need for more bone and ligamentous resection.17 Other authors have
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treated highly migrated lumbar disc herniation via a percutaneous endoscopic interlaminar or
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transforaminal approach. The authors concluded that an interlaminar approach is superior to
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the transforaminal approach. However, a rate for repeat procedure due to incomplete resection
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of the disc herniation of up to 11% was reported. 18-20Anatomical studies have reported that
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the isthmus of the lamina of L2-3 and L3-4 is smaller compared to the lower segments L4-5
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and L5-S1 and therefore the preforaminal and foraminal zone in these particular upper
3
segments is not completely covered by the lamina whereas the disc space is almost
4
completely covered.21 Disc herniations occur more frequently in the lower segments, in which
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the foraminal zone is almost completely covered by the lamina and the proportion of disc
6
space which is overlapped by the lamina decreases. 22Previously, it has been reported that
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tubular assisted endoscopic techniques offer good clinical outcome for the treatment of
8
degenerative lumbar and cervical pathologies. 23-25 The tubular retractor system allows to
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approaching the pathology without additional tissue dissection via a step trajectory. Therefore
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the authors were able to perform endoscopic ILA for the treatment of caudally and cranially
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migrated disc herniation in the lower lumbar segments. Meticulous planning of the skin
12
incision and positioning of the working trocar are essential to successfully perform the
13
procedure. An example of the possible trajectory is shown in figure 2.
14
To the best of the authors` knowledge there is only one report available on endoscopic ILA.
15
Ikuta et al. reported about seven patients with a mean follow-up of 14 month who were
16
treated for cranially migrated lumbar disc herniation. In this particular series the clinical
17
success rate was 100% and all patients showed improvement of clinical symptoms.
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Compared to the findings of Ikuta et al. our clinical success rate of 89.7% was lower in a
19
longer follow-up but among patients without an enlargement of ILA the clinical success rate
20
increased to 95%. The mean operative time was 58 minutes and therefore not prolonged
21
compared to standard microsurgical technique. 15
22
Operating through a trocar with 15mm or 19mm outer diameter is often criticized for poor
23
instrument handling. The authors have demonstrated that this critic is not justifiable. The rate
24
of improvement of clinical symptoms, the rate of dural tear (i.e.6.4%) and the rate recurrent
25
disc herniation were not higher in the present study compared to microsurgical techniques.
26
The tubular dilation system offers the advantage to access the lamina with optimal trajectory
27
and without excessive tissue and muscle trauma. Further the 25° angled view of the
28
endoscope provides an excellent illumination of the surgical field which might increases
29
surgical safety.
30
However, the authors recommend the careful planning of the skin incision for which a
31
preoperative MRI with sagittal, axial, and coronal images is mandatory for the localization of
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a cranially or caudally sequestrated disc herniation. Intraoperative fluoroscopic should be
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used to ensure that the trajectory of the working trocar points directly towards the disc
34
herniation.
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Several factors might have influence on the feasibility to perform the ILA successfully. A
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hypertrophy facet joint will limit the access to the lamina. Further any kind of manipulation at
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the hemilamina previously to the ILA will compromise the feasibility of endoscopic ILA.
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Additional compression of the nerve root due to foraminal stenosis or lateral recess stenosis
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might force the surgeon to enlarge the approach. In 32% of cases the ILA was enlarged due to
6
the aforementioned circumstances. The clinical outcome was not significantly different in this
7
group of patients besides the significantly higher ODI.
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At last it has to be stated that none of the patients with ILA or enlargement of ILA to
9
laminotomy developed new onset of low back pain or any symptom that could be correlated
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to instability of the lumbar spine. However, due to recurrent disc herniation and nerve root
11
adhesion a TLIF as repeat procedure was performed in patient with enlargement of ILA was
12
performed. This might contribute to the fact that the ODI score was significantly higher in this
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group of patients.
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Conclusion
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The endoscopic ILA is a safe and effective technique for resection of caudally and cranially
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migrated lumbar disc herniation. Immediate postoperative pain relief was achieved in 96.3%
18
and clinical success in 89.7% of cases. The rate of recurrent disc herniation was 4.8% within a
19
mean follow-up of 37 month. The ODI was significantly higher in patients with an
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enlargement of the ILA to a laminotomy.
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Acknowledgment
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The authors thank Susanne Mathieu for her contribution to this study.
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Conflict of interest
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Joachim Oertel is a consultant of the Karl Storz company and holds patents on the EasyGO-
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system.
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There has been no financial support for this work that could have influenced its outcome.
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1. Macnab I. Negative disc exploration. An analysis of the causes of nerve-root involvement in sixtyeight patients. The Journal of bone and joint surgery. American volume 1971;53(5):891-903. 2. Segnarbieux F, Van de Kelft E, Candon E, Bitoun J, Frerebeau P. Disco-computed tomography in extraforaminal and foraminal lumbar disc herniation: influence on surgical approaches. Neurosurgery 1994;34(4):643-7; discussion 48. 3. Bernucci C, Giovanelli M. Translaminar microsurgical approach for lumbar herniated nucleus pulposus (HNP) in the "hidden zone": clinical and radiologic results in a series of 24 patients. Spine 2007;32(2):281-4. 4. Epstein NE. Evaluation of varied surgical approaches used in the management of 170 far-lateral lumbar disc herniations: indications and results. Journal of neurosurgery 1995;83(4):648-56. 5. Donaldson WF, 3rd, Star MJ, Thorne RP. Surgical treatment for the far lateral herniated lumbar disc. Spine 1993;18(10):1263-7. 6. Garrido E, Connaughton PN. Unilateral facetectomy approach for lateral lumbar disc herniation. Journal of neurosurgery 1991;74(5):754-56. 7. O'Brien MF, Peterson D, Crockard HA. A posterolateral microsurgical approach to extreme-lateral lumbar disc herniation. Journal of neurosurgery 1995;83(4):636-40. 8. Di Lorenzo N, Porta F, Onnis G, Cannas A, Arbau G, Maleci A. Pars interarticularis fenestration in the treatment of foraminal lumbar disc herniation: a further surgical approach. Neurosurgery 1998;42(1):87-9; discussion 89-90. 9. Soldner F, Hoelper BM, Wallenfang T, Behr R. The translaminar approach to canalicular and craniodorsolateral lumbar disc herniations. Acta neurochirurgica 2002;144(4):315-20. 10. Foley KT, Smith MM. Microendoscopic discectomy. Tech Neurosurg 1997(3):301-07. 11. Philipps M, Oertel J. High-definition imaging in spinal neuroendoscopy. Minimally invasive neurosurgery : MIN 2010;53(3):142-6. 12. Conrad J, Philipps M, Oertel J. High-definition imaging in endoscopic transsphenoidal pituitary surgery. American journal of rhinology & allergy 2011;25(1):e13-7. 13. Ikuta K, Tono O, Senba H, Kitamura T, Komiya N, Oga M, et al. Translaminar microendoscopic herniotomy for cranially migrated lumbar disc herniations encroaching on the exiting nerve root in the preforaminal and foraminal zones. Asian spine journal 2013;7(3):190-5. 14. Fairbank JC, Couper J, Davies JB, O'Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy 1980;66(8):271-3. 15. Papavero L, Langer N, Fritzsche E, Emami P, Westphal M, Kothe R. The translaminar approach to lumbar disc herniations impinging the exiting root. Neurosurgery 2008;62(3 Suppl 1):173-7; discussion 77-8. 16. Vogelsang JP. The translaminar approach in combination with a tubular retractor system for the treatment of far cranio-laterally and foraminally extruded lumbar disc herniations. Zentralblatt fur Neurochirurgie 2007;68(1):24-8. 17. Hussein M. Minimal Incision, Multifidus-sparing Microendoscopic Diskectomy Versus Conventional Microdiskectomy for Highly Migrated Intracanal Lumbar Disk Herniations. The Journal of the American Academy of Orthopaedic Surgeons 2016;24(11):805-13. 18. Choi KC, Kim JS, Ryu KS, Kang BU, Ahn Y, Lee SH. Percutaneous endoscopic lumbar discectomy for L5-S1 disc herniation: transforaminal versus interlaminar approach. Pain physician 2013;16(6):547-56. 19. Kim CH, Chung CK, Woo JW. Surgical Outcome of Percutaneous Endoscopic Interlaminar Lumbar Discectomy for Highly Migrated Disk Herniation. Clinical spine surgery 2016;29(5):E259-66. 20. Yadav YR, Parihar V, Kher Y, Bhatele PR. Endoscopic inter laminar management of lumbar disease. Asian journal of neurosurgery 2016;11(1):1-7. 21. Reulen HJ, Muller A, Ebeling U. Microsurgical anatomy of the lateral approach to extraforaminal lumbar disc herniations. Neurosurgery 1996;39(2):345-50; discussion 50-1.
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22. Dammers R, Koehler PJ. Lumbar disc herniation: level increases with age. Surgical neurology 2002;58(3-4):209-12; discussion 12-3. 23. Oertel JM, Mondorf Y, Gaab MR. A new endoscopic spine system: the first results with "Easy GO". Acta neurochirurgica 2009;151(9):1027-33. 24. Burkhardt BW, Qadeer M, Oertel JMK, Sharif S. Full Endoscopic Interlaminar Lumbar Disc Surgery: Is it the Gold Standard Yet? World Spinal Column Journal 2014;5(2):88-95. 25. Oertel JM, Philipps M, Burkhardt BW. Endoscopic Posterior Cervical Foraminotomy as a Treatment for Osseous Foraminal Stenosis. World neurosurgery 2016;91:50-57.
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Figure legend
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Figure 1: Illustration showing the anatomical localization of possible disc herniation
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Figure 2: Trajectory for cranially and caudally sequestrated disc herniation
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a, b: posterolateral (a) and posterior (b) view onto possible ILA (red areas): line 1 and line 3
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simulate the trajectory for a cranial sequestrated disc herniation and line 2 and 4 simulate the
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trajectory for a caudally sequestrated disc herniation
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Figure 3: Intraoperative set up and procedure planning
a: Patient position und installation of lateral fluoroscopy b, c:Identification of the segment via
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a spinal tap needle. The trajectory should be perpendicular to disc space d: Marking of skin
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incision.
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Figure 4: Application of the EasyGO-system
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a: Insertion of the first dilator. b: Application of the working trocar after muscle dilation. c:
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Fully installed EasyGO-system d: Bimanual surgical technique.
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Figure 5: Preoperative MRI scan
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a: Sagittal image of a L4-5 cranial migrated disc sequester (arrow), b: Axial image of the left
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sided disc sequester
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Figure 6: Intralaminar approach and sequestrectomy
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a: A 3mm diamond drill is used to thin out the lamina, b: The margin of the intralaminar
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fenestration (stars) and exposure of the ligamnetum flavum and the epidural fat c: Flavectomy
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with a 3mm Kerrsion punch, d: Lamina (1), epidural fat (2) and lateral aspect of the dural sac
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(black arrow) is exposed, e: Dural sac (black arrow) and sequester (white arrow) is mobilized
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with a nerve hook, f: A grasper is used for sequestrectomy
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Video legend
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Video 1: Endoscopic ILA for left sided L4-5 disc herniation
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Table legend
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Table 1: Modified MacNab Criteria
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Table 2: Clinical outcome at final follow-up 15
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Good
Marked improvement but occasional pain
Fair
Some improvement with the need for pain medications and significant restrictions in physical activities
Poor
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No improvement, or worse as compared with the condition before operation Table 1: Criteria for clinical outcome
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Modified MacNab criteria Excellent Complete resolution of symptoms
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0.926 0.220 0.339 0.076 0.220 0.220 0.046 0.076
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Mean follow-up (in month) 36.0 No leg pain 19 / 95.0% No back pain 17 / 85.0% Full motor strength 19 / 95.0% No sensory deficit 19 / 95.0% Clinical success 19 / 95.0% Mean ODI 9% Repeat procedure 1 / 5% Table 2 Clinical outcome at final follow-up
Enlargement of ILA to conventional laminotomy (9 patients) 40.0 7 / 77.7% 6 / 66.7% 6 / 66.7% 7 / 77.7% 7 / 77.7% 16 % 3 / 33.3%
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ILA only (20 patients)
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ACCEPTED MANUSCRIPT Highlights Shear intralaminar approach was possible in 21 out of 31 procedures (68%). 95.0% of patients with no leg pain or improved leg pain and excellent or good functional recovery. 85.0% of patients without back pain while follow-up.
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Recurrent disc herniation rate is 4.8%.
S1878-8750(17)30455-2
DOI:
10.1016/j.wneu.2017.03.132
Reference:
WNEU 5501
To appear in:
World Neurosurgery
Received Date: 10 November 2016 Revised Date:
27 March 2017
Accepted Date: 28 March 2017
Please cite this article as: Oertel JM, Burkhardt BW, Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.03.132. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Oertel et al.
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Endoscopic Intralaminar Approach for the Treatment of Lumbar Disc Herniation
Joachim M. Oertel, M.D. and Benedikt W. Burkhardt, M.D.
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Corresponding author Prof. Dr. Joachim M. Oertel Klinik für Neurochirurgie Kirrbergerstraße 100 66421, Homburg-Saar Germany Phone: +49-6841-1624400 Fax: +49-6841-1624480 Email: [email protected]
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Department of Neurosurgery, Saarland University Medical Center and Saarland University Faculty of Medicine, Homburg-Saar, Germany
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Background
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Almost every surgical approach carries the risk to cause some degree of spinal instability,
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especially in case of excessive resection of the lamina and facet joint. This study describes the
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endoscopic intralaminar approach (ILA) for the treatment of cranially and caudally migrated
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lumbar disc herniation.
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Methods
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Thirty-one patients who underwent endoscopic ILA for 26 caudally and 5 cranially migrated
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lumbar disc herniation were identified from a prospectively database. At final follow-up a
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personal examination and a standardized questionnaire was conducted including Oswestry
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Disability Index (ODI), functional outcome according to modified MacNab Criteria.
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Additionally particular reference was given to back-pain, leg-pain and repeat procedure.
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Results
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The mean final follow-up was 37.0 month (range 5-57 month) at which 29 patients attended
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(93.5%). No leg pain was noted in 95.0%, no back pain in 85.0%, full motor strength in
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95.0%, and no sensory deficit in 95.0% of patients with ILA. Clinical success was reported by
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95.0% of patients and the mean ODI was 9% in patients with ILA. Ten patients had an
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enlargement of ILA to conventional laminotomy (32.3%). By comparison of clinical outcome
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and repeat procedure rate in patients with ILA to patients with enlargement to laminotomy no
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significant differences were identified except for higher ODI (i.e.16%) in patients with
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enlargement of ILA.
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Conclusion
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Endoscopic ILA is a safe technique for the treatment of cranially and caudally migrated
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lumbar disc herniations. Careful procedure planning is recommended to protection of soft
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tissue and osseous structures and to achieve excellent clinical outcome.
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Oertel et al.
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Lumbar disc herniation is a common degenerative disease in the western countries. In 1971
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Macnab described the term “hidden zone” for migrated disc herniations.1 According to
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Macnab the lateral zone of the spinal canal can be divided into three sections, including the
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subarticular zone, the foraminal zone, and the extraforaminal zone. A disc herniation that is
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located between the medial and lateral margin of the two adjacent pedicles it is considered to
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be in the foraminal zone.1 2 A disc herniation that is located laterally to a line of the lateral
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margin of the two adjacent pedicles is considered to be extraforaminal or far lateral. Other
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authors used the term “preforaminal zone” instead of “hidden zone“ to describe this particular
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localization.3 If the disc herniation occurs at the “preforaminal zone” or “hidden zone” the
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surgical approach might be associated with difficulties.2
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Caspar et al first described the microsurgical interlaminar approach which might be unsuitable
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for pathologies located in the “hidden zone” unless the approach is extended to a
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hemilaminectomy with partial or complete facetectomy for better exposure of the
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Neuroforamen. This extension might carry the risk of instability due to destruction. 4-6 An
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approach via lateral fenestration or posterolateral approach is less destructive and preserves
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the stability of the lumbar spine but offers poor exposure of the medial foraminal portion.2 7 In
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1998, Di Lorenzo et al. proposed treating foraminal and preforaminal lumbar disc herniation
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via a “pars interarticularis fenestration” by sparing the partial resection of the facet joint8.
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Soldner et al. described a similar but modified approach and called it “intralaminar approach”
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(ILA). However, the ILA describes by Soldner and Di Lorenzo was followed by tissue and
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muscle dissection. 8 9
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In the past decades tubular assisted surgery was introduced to spinal surgery to combine
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bimanual microsurgical technique with reduced the tissue and muscle trauma during the
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surgical approach. 10 Additionally since 2007 the HD-endoscopic visualization is available
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and allows for better illumination and tissue identification compared to previous standard
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definition. 11 12
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To the best of our knowledge this is the first report of a series of 29 patients with caudally and
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cranially migrated disc herniation who were operated via endoscopic ILA. The purpose of this
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study was to describe the surgical technique, clinical outcome, and feasibility of endoscopic
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ILA.
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Material and Methods
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Patient population
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Retrospectively, the surgical report and the endoscopic video recording of all patients who
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underwent endoscopic procedure for the treatment of lumbar disc herniation from January
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2011 to December 2015 were reviewed. Only patients in whom the surgeon had the intention
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to resect a migrated lumbar disc herniation via an endoscopic ILA were selected for further
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clinical and radiological evaluation. Evaluation included the review of preoperative and
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postoperative patient record, evaluation of endoscopic video recording as well as the
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evaluation of the preoperative MRI scan. The localization of the disc herniation was defined
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according to the classification of Ikuta et al. (Figure 1) 13. The endoscopic video recording
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was reviewed to analyze the diameter of the intralaminar approach and whether an
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enlargement of the ILA was performed. The authors defined the enlargement of the ILA to a
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conventional laminotomy as follows: once a portion of the superior or inferior edge of the
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lamina was not intact (e.g. thinned out by diamond drilling or resected via a Kerrsion punch).
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At final follow-up a physical examination and a standardized questionnaire were conducted.
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The questionnaire included the Oswestry Disability Index (ODI) 14, functional outcome
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according to modified MacNab Criteria (Table 1). Clinical success was defined as excellent
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and good result according to MacNab criteria.
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Surgical equipment
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All procedures were performed with the EasyGO® spine system. The endoscopic equipment
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consisted of a 30° Hopkins® Forward-Oblique telescopes with 9.5 cm in length, a H3-Z Full
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HD Camera Head and a Xenon Nova® 300 cold light fountain. The intraoperative image was
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transmitted on a 26" HD Flat Screen. All intraoperative data was recorded via AIDA®
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compact NEO data archiving system (KARL STORZ GmbH & Co. KG, Tuttlingen,
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Germany).
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Surgical technique
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Prior to surgery the preoperative lumbar MRI analyzed to plan the trajectory of the working
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trocar. The trajectory of the working trocar varies depending on the operated segment and
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might get very step, especially in caudally sequestrated disc herniation (Figure 2). The
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procedure is performed under general anesthesia, preoperative antibiosis is admitted. Patient
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is place central on the operating table in prone position. The neck is in neutral position, 4
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abdomen is decompressed on a Wilson frame and pressure points are padded and a C-arm for
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lateral fluoroscopy is installed. A spinal tap needle is used to identify the affected segment
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(Figure 3).
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The trajectory of the needle should be perpendicular to the disc herniation. Skin incision is
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about 2 cm paramedian of the spinous process and about 1.4 – 1.8 cm in length depending on
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the selected trocar After the muscle fascia is opened the smallest dilator is put in direct
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contact to the bony surface of the hemilamina under lateral fluoroscopic control. Soft tissue
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and muscles are be pushed away and dilated by sliding the various dilators one over the other.
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After tissue and paraspinal muscle dilation the working trocar is placed fixed in position via a
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holding arm. The three-chip high definition (HD) camera head is introduced and placed in
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correct position. The full-HD endoscopic unit is generally positioned on the other side of the
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operation table so the surgeon can also assume a more comfortable position while doing the
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surgery in bimanual technique (Figure 4). A preoperative MRI scan and the accompanying
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main steps of the ILA and sequestrectomy are shown on figure 5 and figure 6. A more
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detailed case is demonstrated on video 1.
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The authors performed a partial discectomy in cases of identification of a large annulus
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perforation. After sequestrectomy the working trocar is recommended to be removed under
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endoscopic control to detect and immediately treat bleeding source of the paraspinal muscle.
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The thoracolumbar fascia can be closed using 2.0 interrupted sutures. In obese patients it is
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recommended to adapt subcutaneous tissue followed by subcuticular suture. A skin adhesive
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allows the patient to shower on the first postoperative day.
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Statistical Analysis
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Statistics were calculated using SPSS version 23 (IBM, Armonk, NY, USA). The paired t-
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test, Mann Whitney test, Wilcoxon test, and Fisher exact test were used for analysis. Any P
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values were given two-sided. A P value of <0.05 was assumed to be sufficient to indicate
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statistical significance.
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Patient Demographics
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One hundred and forty-two patients underwent endoscopic procedure for lumbar disc
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herniation. In thirty-one patients (17 male and 14 female) the intention to perform an ILA for
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the resection of a migrated lumbar disc herniation was noted in the surgical report. According
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to the surgical report the surgeon choose an interlaminar approach in the remaining 111
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procedures due to localization and shape of the disc herniation or concurrent stenosis of the
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lateral recess. The mean age at endoscopic procedure was 52.1 years (range 31-82 years), the
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mean duration of symptoms prior to endoscopic procedure was 5.3 month according to the
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documentation in the file.
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The preoperative MRI scan and the endoscopic video recording revealed the diagnosis of a
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lumbar disc herniation in all cases.
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The primarily indication for endoscopic ILA was radicular pain resistant to conservative
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treatment, a motor deficit, or a sensory deficit. The L2 lamina was involved in one (3.2%), L3
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lamina in five (16.1%), L4 lamina in fourteen (45.2%), and L5 in eleven ILAs (35.5%).
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Preoperative MRI Evaluation
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The disc herniation was sequestrated caudally in 26 cases (83.9%), and in five cases it was
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sequestrated cranially to the disc level (16.1%).
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The analysis of the localization of the disc herniation revealed that it was sequestrated into the
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subarticular zone in 13 (41.9%), into the preforaminal zone in 2 (6.5%), into the foraminal
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zone in 1 (3.2%), into the subarticular and the preforaminal zone in 6 (19.4%), into the
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subarticular and foraminal zone in 3 (9.7%), into the preforaminal and foraminal zone in 3
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(9.7%), and into all three zones in 3 (9.7%) cases.
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Endoscopic Video Recording Evaluation
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The endoscopic video recording revealed a successfully performed endoscopic ILA in 21
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cases (67.7%) and an enlargement of the endoscopic ILA to a laminotomy in 10 cases
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(32.3%).
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A more detailed analysis of the ten cases with enlargement indicated that had pervious lumbar
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surgery at the adjacent level was performed in three cases. Therefore the feasibility to perform
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endoscopic ILA was compromised because the hemilamina in those three cases was partially
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resected and the surface was diminished prior to endoscopic ILA.
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In another three cases the ILA was enlarged after sequestrectomy for further decompression
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of the nerve root via foraminotomy.
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In two cases the ILA was enlarged for better exposure and resection of a subligamentous disc
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herniation. At last in two case the inferior edge of the hemilamina was incidentally drilled
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while ILA.
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Intraoperative Findings
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Mean overall operating time in all procedures was 54 minutes (range 25 – 85) minutes.
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Seventeen patients were operated via a 15mm and fourteen patients via a 19mm working trocar.
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In all cases, the disc herniation was identified and removed. Intraoperatively in 18 cases a
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perforation of the annulus was identified and consecutive partial discectomy was performed
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(58.1%).
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No emergency stopping with switching to microsurgery was required. The mean diameter was
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for ILA was 7 mm (range 5-9 mm). The diameter was measure as the ratio of the outer
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diameter of the suction tube to the actual ILA.
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In two cases a dural tear occurred which was closed endoscopically with a combination of an
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autologous muscle patch and a collagen sponge coated with the human coagulation factors
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fibrinogen and thrombin. None of the two patients reported any kind of discomfort which
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could be related to the CSF leak or pseudomeningocele.
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Clinical Findings: Preoperative, Postoperative & Final Follow-up
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At final follow-up 29 out of 31 patients (17 male and 12 female) attended the physical
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examination and standardized questionnaire at our Neurosurgical Department (93.5%). The
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mean follow-up time was 37.0 month (range 5-57 month).
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Preoperatively 27 patients had radicular pain (93.1%), fifteen patients had a motor deficit
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(51.7%), and eleven patients had a sensory disturbance (37.9%). The mean leg pain intensity
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on the NPRS was 7 (range: 0 – 10), the mean back pain intensity on the NPRS was 6 (range: 0
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– 10).
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Four patients had a history of chronic back pain prior to their onset of a new radicular
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disturbance. One patient had a paresis and sensory deficit since over 30 years due to previous
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lumbar disc surgery.
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Postoperatively all patients were mobilized at the day of surgery. Twenty-six patients reported
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to be pain free or with improved leg pain (96.3%), thirteen patients reported an improvement
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in motor strength (86.7%), and eleven of patients reported an improvement of their
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preoperative sensory disturbance (100%). The mean leg pain intensity on the NRPS decreased
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to 1 (range: 0 -7), which was statistical significant (p< 0.001). The mean back pain intensity
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on the NRPS was decreased to 2 (range: 0 – 7), which was statistical significant (p< 0.001).
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No postoperative wound healing problems or wound infection were noted. One patient with a
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history of chronic low back pain underwent endoscopic procedure due new paresis. The
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paresis completely recovered but the patient reported n new onset on radicular pain. The
postoperative MRI and radiograph showed no signs of nerve root compression or instability.
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At final follow-up examination twenty-four patients reported to be free of leg pain (88.7%),
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one patients reported to have intermittent leg pain (3.4%), and two patients reported to have
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mild leg pain while physical activity (6.9%). None of the patients reported to take pain
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medication regularly. Twenty-three patients reported to have no back pain (79.3%), four
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patients reported to have back pain (13.8%). Among those four patients two patients had a
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history of chronic back pain and two patients underwent repeat procedure due to degenerative
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disorders after endoscopic procedure. Two patients reported to have low back pain while
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sports activity (6.9%). Among those two one patient had a history of chronic low back pain.
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Twenty-five patients had full motor strength (86.2%), in three patients a mild (4/5) residual
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paresis remained (10.3%), and in one patient the former documented paresis due to previous
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surgery remained the same (3.4%).
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Twenty-six patients had no sensory deficit (89.7%), one patient had a residual sensory deficit
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(3.4%), in one patient the former documented sensory deficit due to previous surgery
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remained the same (3.4%), and one patient reported a new onset of sensory disturbance
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(3.4%)
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According to the MacNab criteria 26 patients reported to have excellent or good results
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(89.7%). The mean ODI was 11.0% (range: 0% - 64%). The ODI ranged from 24% - 64%
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among patients with a history of low back pain. By excluding patients with a history of low
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back pain the mean ODI decreased to 5%. (range: 0% - 24%).
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An analysis of clinical outcome at final follow-up separated for patients with ILA only and
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patients with enlargement of ILA to conventional laminotomy is shown on table 2.
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Patients with repeat lumbar spine procedure: Among those patients with successfully
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performed ILA one patient reported a new onset of radicular pain on the seventh
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postoperative day and underwent repeat microsurgical discectomy for recurrent disc
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herniation. The same patient was operated at the cranial adjacent segment due to another disc
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herniation 17 month after the initial endoscopic surgery.
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Among those nine patients with an enlargement of ILA to conventional laminotomy three
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patients underwent repeat procedure. One patient had a recurrent disc herniation four month
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after initial endoscopic procedure and underwent microsurgical discectomy. The same patient
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had a recurrent disc herniation with consecutive spondylolisthesis two years after initial
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surgery and underwent transforaminal lumbar interbody fusion (TLIF). Another patient with a
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history of chronic back pain underwent nerve root adhesiolysis and TLIF four month after
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initial endoscopic procedure. At last one patient underwent repeat surgery for lateral recess
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stenosis at the contralateral side three years after initial surgery.
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Lost at follow-up
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Two patients were lost at follow-up. According to the files one patient had a new onset of
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radicular pain and a motor deficit 15 month after the initial endoscopic procedure. The MRI
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scan revealed a disc herniation at the index segment on the contralateral side and the patient
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underwent repeat microsurgical discectomy. According to the outpatient note an improvement
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of leg pain and motor deficit was documented. The second patient had an enlargement of ILA
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to conventional laminotomy. According to the outpatient note an improvement of leg pain
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was documented.
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The ideal approach for the treatment of cranially or caudally migrated lumbar disc herniations
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is still controversial. Migrated lumbar disc herniation can be exposed via an interlaminar
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approach but extensive resection of the lamina might be necessary for exposure. Especially
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bone removal at the pars interarticularis might lead to spinal instability and cause
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postoperative back pain. The direct approach by “fenestration of the pars interarticularis” was
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first described by Di Lorenzo. Critics eyed Di Lorenzo`s approach very skeptical. 8
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Shortly after the so called “intralaminar fenestration” was presented by Soldner el al. It was a
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modification of Di Lorenzo`s approach with preservation of the pars interarticularis. Good to
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excellent clinical outcome in 90% to 100% of cases and a recurrent disc herniation rate of 3%
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to 7% have been reported. 3 9 15
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In contrast to the present study the majority of studies reported about the treatment of
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cranially migrated disc herniations. Papavero et al. reported a series of 104 patients with a
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mean follow-up of 27 month who underwent ILA. It was stated that ILA is a safe surgical
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technique for the removal of cranially migrated disc herniations. However, Papavero was of
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the opinion that the recurrent disc herniation rate of 7% was caused by the fact that
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discectomy was performed in only 15% of his series. 3 13 15 16 15
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In the present study a partial discectomy was performed in 58% of all cases, which might be
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the reason for slightly lower recurrent disc herniation rate on the ipsilateral side was (i.e.
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4.8%). However, the present study design is not suited to assess whether partial discectomy
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should be performed to achieve lower recurrent disc herniation rate or not. Tubular assisted
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spine surgery is considered to be as effective as open microsurgical technique with the
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advantage of less muscle and tissue trauma.
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Hussein evaluated the clinical outcome of 36 patients who underwent endoscopic tubular
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assisted interlaminar approach for the treatment of cranially migrated lumbar disc herniation.
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In his series with a two year follow-up the mean ODI was about 20% and three patients
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underwent repeat procedure due to no improvement or recurrence of radicular pain (n=2) and
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new mechanical low back pain (n=1). Interestingly the mean surgical time in the endoscopic
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groups was 85 minutes in therefore 30 minutes compared to our groups. This difference might
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be cause due to the need for more bone and ligamentous resection.17 Other authors have
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treated highly migrated lumbar disc herniation via a percutaneous endoscopic interlaminar or
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transforaminal approach. The authors concluded that an interlaminar approach is superior to
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the transforaminal approach. However, a rate for repeat procedure due to incomplete resection
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of the disc herniation of up to 11% was reported. 18-20Anatomical studies have reported that
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the isthmus of the lamina of L2-3 and L3-4 is smaller compared to the lower segments L4-5
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and L5-S1 and therefore the preforaminal and foraminal zone in these particular upper
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segments is not completely covered by the lamina whereas the disc space is almost
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completely covered.21 Disc herniations occur more frequently in the lower segments, in which
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the foraminal zone is almost completely covered by the lamina and the proportion of disc
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space which is overlapped by the lamina decreases. 22Previously, it has been reported that
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tubular assisted endoscopic techniques offer good clinical outcome for the treatment of
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degenerative lumbar and cervical pathologies. 23-25 The tubular retractor system allows to
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approaching the pathology without additional tissue dissection via a step trajectory. Therefore
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the authors were able to perform endoscopic ILA for the treatment of caudally and cranially
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migrated disc herniation in the lower lumbar segments. Meticulous planning of the skin
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incision and positioning of the working trocar are essential to successfully perform the
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procedure. An example of the possible trajectory is shown in figure 2.
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To the best of the authors` knowledge there is only one report available on endoscopic ILA.
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Ikuta et al. reported about seven patients with a mean follow-up of 14 month who were
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treated for cranially migrated lumbar disc herniation. In this particular series the clinical
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success rate was 100% and all patients showed improvement of clinical symptoms.
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Compared to the findings of Ikuta et al. our clinical success rate of 89.7% was lower in a
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longer follow-up but among patients without an enlargement of ILA the clinical success rate
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increased to 95%. The mean operative time was 58 minutes and therefore not prolonged
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compared to standard microsurgical technique. 15
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Operating through a trocar with 15mm or 19mm outer diameter is often criticized for poor
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instrument handling. The authors have demonstrated that this critic is not justifiable. The rate
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of improvement of clinical symptoms, the rate of dural tear (i.e.6.4%) and the rate recurrent
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disc herniation were not higher in the present study compared to microsurgical techniques.
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The tubular dilation system offers the advantage to access the lamina with optimal trajectory
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and without excessive tissue and muscle trauma. Further the 25° angled view of the
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endoscope provides an excellent illumination of the surgical field which might increases
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surgical safety.
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However, the authors recommend the careful planning of the skin incision for which a
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preoperative MRI with sagittal, axial, and coronal images is mandatory for the localization of
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a cranially or caudally sequestrated disc herniation. Intraoperative fluoroscopic should be
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used to ensure that the trajectory of the working trocar points directly towards the disc
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herniation.
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Several factors might have influence on the feasibility to perform the ILA successfully. A
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hypertrophy facet joint will limit the access to the lamina. Further any kind of manipulation at
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the hemilamina previously to the ILA will compromise the feasibility of endoscopic ILA.
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Additional compression of the nerve root due to foraminal stenosis or lateral recess stenosis
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might force the surgeon to enlarge the approach. In 32% of cases the ILA was enlarged due to
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the aforementioned circumstances. The clinical outcome was not significantly different in this
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group of patients besides the significantly higher ODI.
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At last it has to be stated that none of the patients with ILA or enlargement of ILA to
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laminotomy developed new onset of low back pain or any symptom that could be correlated
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to instability of the lumbar spine. However, due to recurrent disc herniation and nerve root
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adhesion a TLIF as repeat procedure was performed in patient with enlargement of ILA was
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performed. This might contribute to the fact that the ODI score was significantly higher in this
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group of patients.
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Conclusion
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The endoscopic ILA is a safe and effective technique for resection of caudally and cranially
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migrated lumbar disc herniation. Immediate postoperative pain relief was achieved in 96.3%
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and clinical success in 89.7% of cases. The rate of recurrent disc herniation was 4.8% within a
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mean follow-up of 37 month. The ODI was significantly higher in patients with an
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enlargement of the ILA to a laminotomy.
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Acknowledgment
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The authors thank Susanne Mathieu for her contribution to this study.
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Conflict of interest
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Joachim Oertel is a consultant of the Karl Storz company and holds patents on the EasyGO-
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system.
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There has been no financial support for this work that could have influenced its outcome.
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1. Macnab I. Negative disc exploration. An analysis of the causes of nerve-root involvement in sixtyeight patients. The Journal of bone and joint surgery. American volume 1971;53(5):891-903. 2. Segnarbieux F, Van de Kelft E, Candon E, Bitoun J, Frerebeau P. Disco-computed tomography in extraforaminal and foraminal lumbar disc herniation: influence on surgical approaches. Neurosurgery 1994;34(4):643-7; discussion 48. 3. Bernucci C, Giovanelli M. Translaminar microsurgical approach for lumbar herniated nucleus pulposus (HNP) in the "hidden zone": clinical and radiologic results in a series of 24 patients. Spine 2007;32(2):281-4. 4. Epstein NE. Evaluation of varied surgical approaches used in the management of 170 far-lateral lumbar disc herniations: indications and results. Journal of neurosurgery 1995;83(4):648-56. 5. Donaldson WF, 3rd, Star MJ, Thorne RP. Surgical treatment for the far lateral herniated lumbar disc. Spine 1993;18(10):1263-7. 6. Garrido E, Connaughton PN. Unilateral facetectomy approach for lateral lumbar disc herniation. Journal of neurosurgery 1991;74(5):754-56. 7. O'Brien MF, Peterson D, Crockard HA. A posterolateral microsurgical approach to extreme-lateral lumbar disc herniation. Journal of neurosurgery 1995;83(4):636-40. 8. Di Lorenzo N, Porta F, Onnis G, Cannas A, Arbau G, Maleci A. Pars interarticularis fenestration in the treatment of foraminal lumbar disc herniation: a further surgical approach. Neurosurgery 1998;42(1):87-9; discussion 89-90. 9. Soldner F, Hoelper BM, Wallenfang T, Behr R. The translaminar approach to canalicular and craniodorsolateral lumbar disc herniations. Acta neurochirurgica 2002;144(4):315-20. 10. Foley KT, Smith MM. Microendoscopic discectomy. Tech Neurosurg 1997(3):301-07. 11. Philipps M, Oertel J. High-definition imaging in spinal neuroendoscopy. Minimally invasive neurosurgery : MIN 2010;53(3):142-6. 12. Conrad J, Philipps M, Oertel J. High-definition imaging in endoscopic transsphenoidal pituitary surgery. American journal of rhinology & allergy 2011;25(1):e13-7. 13. Ikuta K, Tono O, Senba H, Kitamura T, Komiya N, Oga M, et al. Translaminar microendoscopic herniotomy for cranially migrated lumbar disc herniations encroaching on the exiting nerve root in the preforaminal and foraminal zones. Asian spine journal 2013;7(3):190-5. 14. Fairbank JC, Couper J, Davies JB, O'Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy 1980;66(8):271-3. 15. Papavero L, Langer N, Fritzsche E, Emami P, Westphal M, Kothe R. The translaminar approach to lumbar disc herniations impinging the exiting root. Neurosurgery 2008;62(3 Suppl 1):173-7; discussion 77-8. 16. Vogelsang JP. The translaminar approach in combination with a tubular retractor system for the treatment of far cranio-laterally and foraminally extruded lumbar disc herniations. Zentralblatt fur Neurochirurgie 2007;68(1):24-8. 17. Hussein M. Minimal Incision, Multifidus-sparing Microendoscopic Diskectomy Versus Conventional Microdiskectomy for Highly Migrated Intracanal Lumbar Disk Herniations. The Journal of the American Academy of Orthopaedic Surgeons 2016;24(11):805-13. 18. Choi KC, Kim JS, Ryu KS, Kang BU, Ahn Y, Lee SH. Percutaneous endoscopic lumbar discectomy for L5-S1 disc herniation: transforaminal versus interlaminar approach. Pain physician 2013;16(6):547-56. 19. Kim CH, Chung CK, Woo JW. Surgical Outcome of Percutaneous Endoscopic Interlaminar Lumbar Discectomy for Highly Migrated Disk Herniation. Clinical spine surgery 2016;29(5):E259-66. 20. Yadav YR, Parihar V, Kher Y, Bhatele PR. Endoscopic inter laminar management of lumbar disease. Asian journal of neurosurgery 2016;11(1):1-7. 21. Reulen HJ, Muller A, Ebeling U. Microsurgical anatomy of the lateral approach to extraforaminal lumbar disc herniations. Neurosurgery 1996;39(2):345-50; discussion 50-1.
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22. Dammers R, Koehler PJ. Lumbar disc herniation: level increases with age. Surgical neurology 2002;58(3-4):209-12; discussion 12-3. 23. Oertel JM, Mondorf Y, Gaab MR. A new endoscopic spine system: the first results with "Easy GO". Acta neurochirurgica 2009;151(9):1027-33. 24. Burkhardt BW, Qadeer M, Oertel JMK, Sharif S. Full Endoscopic Interlaminar Lumbar Disc Surgery: Is it the Gold Standard Yet? World Spinal Column Journal 2014;5(2):88-95. 25. Oertel JM, Philipps M, Burkhardt BW. Endoscopic Posterior Cervical Foraminotomy as a Treatment for Osseous Foraminal Stenosis. World neurosurgery 2016;91:50-57.
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Figure legend
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Figure 1: Illustration showing the anatomical localization of possible disc herniation
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Figure 2: Trajectory for cranially and caudally sequestrated disc herniation
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a, b: posterolateral (a) and posterior (b) view onto possible ILA (red areas): line 1 and line 3
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simulate the trajectory for a cranial sequestrated disc herniation and line 2 and 4 simulate the
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trajectory for a caudally sequestrated disc herniation
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Figure 3: Intraoperative set up and procedure planning
a: Patient position und installation of lateral fluoroscopy b, c:Identification of the segment via
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a spinal tap needle. The trajectory should be perpendicular to disc space d: Marking of skin
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incision.
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Figure 4: Application of the EasyGO-system
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a: Insertion of the first dilator. b: Application of the working trocar after muscle dilation. c:
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Fully installed EasyGO-system d: Bimanual surgical technique.
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Figure 5: Preoperative MRI scan
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a: Sagittal image of a L4-5 cranial migrated disc sequester (arrow), b: Axial image of the left
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sided disc sequester
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Figure 6: Intralaminar approach and sequestrectomy
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a: A 3mm diamond drill is used to thin out the lamina, b: The margin of the intralaminar
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fenestration (stars) and exposure of the ligamnetum flavum and the epidural fat c: Flavectomy
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with a 3mm Kerrsion punch, d: Lamina (1), epidural fat (2) and lateral aspect of the dural sac
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(black arrow) is exposed, e: Dural sac (black arrow) and sequester (white arrow) is mobilized
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with a nerve hook, f: A grasper is used for sequestrectomy
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Video legend
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Video 1: Endoscopic ILA for left sided L4-5 disc herniation
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Table legend
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Table 1: Modified MacNab Criteria
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Table 2: Clinical outcome at final follow-up 15
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Good
Marked improvement but occasional pain
Fair
Some improvement with the need for pain medications and significant restrictions in physical activities
Poor
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No improvement, or worse as compared with the condition before operation Table 1: Criteria for clinical outcome
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Modified MacNab criteria Excellent Complete resolution of symptoms
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0.926 0.220 0.339 0.076 0.220 0.220 0.046 0.076
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Mean follow-up (in month) 36.0 No leg pain 19 / 95.0% No back pain 17 / 85.0% Full motor strength 19 / 95.0% No sensory deficit 19 / 95.0% Clinical success 19 / 95.0% Mean ODI 9% Repeat procedure 1 / 5% Table 2 Clinical outcome at final follow-up
Enlargement of ILA to conventional laminotomy (9 patients) 40.0 7 / 77.7% 6 / 66.7% 6 / 66.7% 7 / 77.7% 7 / 77.7% 16 % 3 / 33.3%
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ILA only (20 patients)
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ACCEPTED MANUSCRIPT Highlights Shear intralaminar approach was possible in 21 out of 31 procedures (68%). 95.0% of patients with no leg pain or improved leg pain and excellent or good functional recovery. 85.0% of patients without back pain while follow-up.
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Recurrent disc herniation rate is 4.8%.