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Dural Tears in Percutaneous Biportal Endoscopic Spine Surgery: Anatomical Location and Management
Journal Pre-proof Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management Hyun-Jin Park, MD, Seung-Kook Kim, MD, PhD, Su-chan Lee, MD, PhD, Wanseok Kim, MD, Sangho Han, MD, Sang-Soo Kang, MD PII:
S1878-8750(20)30098-X
DOI:
https://doi.org/10.1016/j.wneu.2020.01.080
Reference:
WNEU 14110
To appear in:
World Neurosurgery
Received Date: 21 October 2019 Revised Date:
10 January 2020
Accepted Date: 11 January 2020
Please cite this article as: Park H-J, Kim S-K, Lee S-c, Kim W, Han S, Kang S-S, Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management, World Neurosurgery (2020), doi: https://doi.org/10.1016/j.wneu.2020.01.080. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2020 Elsevier Inc. All rights reserved.
Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management
Short Title: Management of dural tears in biportal endoscopic spine surgery
Hyun-Jin Park MDa, Seung-Kook Kim, MD, PhDb,c,d*, Su-chan Lee MD, PhDc. Wanseok Kim MDe, Sangho Han MDe, Sang-Soo Kang MDf
a
Department of Spine Center, Orthopaedic Surgery, Hallym University Kangnam Sacred
Heart Hospital, Korea b
Himchan UHS Spine and Joint Centre, Neurosurgery, University Hospital Sharjah,
University street 1, Sharjah 15485, United Arab Emirates c
Joint and Arthritis Research, Orthopaedic Surgery, Himchan Hospital, sinmok-ro 120, Seoul
17999, Korea d
Department of Pharmaceutical Medicine and Regulatory Sciences, College of Medicine and
Pharmacy, Yonsei University, Songdokwahakro 85, Incheon 21983, Korea e
Department of Spine Center, Orthopaedic Surgery, Daechan Hospital, Korea
f
Department of Spine Center, Orthopaedic Surgery, Leaders Hospital, Cheonhodae-ro 1044,
Seoul 05335, Korea
*Corresponding author: Seung-Kook Kim, Himchan UHS Spine and Joint Centre, Neurosurgery, University Hospital of Sharjah, University street 1, Sharjah 15485, United Arab Emirates Tel: +971-6-505-8555; Fax: +971-6-505-8444; E-mail: [email protected]
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Keywords: dural tear, endoscopic spinal surgery, fibrin sealant, nonpenetrating titanium clip, percutaneous biportal endoscopic surgery
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Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management
Abstract Objective: To determine the rate and anatomical location of dural tears associated with spinal surgery using a percutaneous biportal technique (PBES). We aimed to investigate the relationship between dural tears and the type of procedure and type of instrument used.
Methods: We retrospectively analyzed 643 PBES cases by reviewing medical charts, operative records, and operative videos. Incidental durotomy was identified in 29 cases. We analyzed the size and anatomical location of dural tears, as well as the surgical instrument that caused the tear, and the technique used to seal the tear.
Results: The dural tear incidence was 4.5% (29/643 cases). Tears in the exiting nerve area (two cases, 6.9%) were mainly caused by curettage, while tears in the thecal sac area (18 cases, 62.1%) were associated with electric drill and forceps use, and use of a Kerrison punch in the traversing nerve area (nine cases, 31%). Twelve cases of dural tear were treated with in-hospital monitoring and bed rest. Fourteen cases were treated using a fibrin sealant. Two cases were treated with a non-penetrating titanium clip, and one was converted to microscopic surgery. One case of postoperative meningocele after conservative treatment required endoscopic revision surgery to close the dural tear.
Conclusions: Most cases of incidental dural tear during PBES were treated with an endoscopic procedure. The incidence of dural tear was no higher than that was associated
1
with microscopic surgery. Our management strategy for incidental dural tears in biportal endoscopic spinal surgery is safe and effective.
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Introduction Tearing of the dura is a common intra-operative complication of degenerative lumbar surgery, with an incidence of up to 8.6% reported during narrow endoscopic spinal surgery.1,2 Appropriate intra- and post-operative management may improve patient outcomes; however, the length of hospital stay is usually prolonged and patients may experience side-effects.3 The issue of dural tears is clinically meaningful in light of the increased popularity of minimally invasive spinal surgery, which has increased the rate of complications related to spinal surgery.4 Percutaneous biportal endoscopic surgery (PBES) is a variant of endoscopic spinal surgery that provides the benefits of high definition visualization with simple and with simple and fast laminotomy procedure with various instruments. As such, PBES is performed for various spinal conditions, including stenosis decompression, epidural mass removal, and inter-body fusion surgery.5,6 This technique has been associated with favorable outcomes, including early post-operative recovery and shorter length of hospital stay.7 However, PBES-related complications, including dural tears, have not been thoroughly evaluated. Therefore, the purpose of our study was to determine the rate of dural tears associated with PBES spinal surgery, as well as to identify the common location of these tears, and the relationship between dural tears and the type of procedure undertaken, and the type of instruments used. Our secondary aim was to develop a treatment algorithm for dural tears based on our experience.
Materials and methods
Study design and population
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Our retrospective study included prospectively collected data from 643 consecutive patients who underwent PBES for degenerative spinal disease at our institution between May 2016 and June 2018. Our study was approved by our Institutional Review Board (approval Himchan IRB 169684-01-201904-02), and patients provided written informed consent for surgery and the publication of their data. All recorded medical data, surgical records, and endoscopic videos were collected according to the principles of the Declaration of Helsinki. All surgeries were performed by four experienced spinal surgeons, each having more than eight years of experience in performing microscopic and endoscopic spinal procedures. Cases meeting the following criteria were included in our analysis: 1) unilateral decompression laminectomy, including far lateral decompression for foraminal stenosis; 2) unilateral approach for bilateral decompression in cases of central or lateral recess stenosis; 3) unilateral or bilateral discectomy; and 4) fusion surgeries performed using the PBES technique. Excluded were cases of trauma, primary infection, and all other types of microscopic and uniportal endoscopic surgeries.
Diagnosis of dural tear and evaluation Data were reviewed and analyzed by four experienced physicians, each with more than 10 years of experience in the field of spinal surgery. Preoperative demographic data, operation type, medical condition (American Society of Anesthesiologists Physical Status, ASA-PS) and preoperative radiologic MRI grading8 and CT grading9 were evaluated. The procedures are classified according to anatomical contact between dura and instrument as 1) far lateral; 2) ipsilateral 3); contralateral; 4) bilateral decompression through unilateral; and 5) fusion approach. The anatomical location of the dural tear was classified into the following three zones, based on the anatomy of the peripheral nerve at each level (Fig. 1). Zone 1 referred to the dura over the exiting nerve root, and included shoulder lesions under the lower margin of
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the upper pedicle. Zone 2 referred to the path of the thecal sac, but excluded the axilla of the exiting nerve junction and the shoulder of the traversing nerve between the upper and lower pedicle. Zone 3 referred to the traversing nerve root and included the axillar junction with the thecal sac above the upper margin of the lower pedicle. The size of a dural tear was estimated prior to repair using a surgical instrument of specified length, normally a 3-mm Kerrison punch or a 5-mm hook dissector (Fig. 2). Lastly, irregularity of the margins of the tear was verified to determine the possibility of endoscopic closure.
Dural repair and management When a dural tear was identified, those <4 mm in size were treated with a 24-h period of bed rest and in-hospital observation, without any intra-operative intervention. Regarding the need for management, we confirmed the tearing margin with further laminectomy and dissection. Next, we designed the working portal depending on tools, usually requiring 1–2 mm extension of the incision. Dural tears 4–12 mm in size (intermediate size defect) were closed using a fibrin sealant patch (Tachosil , Baxter, Deerfield, IL, United States), followed by close in-hospital observation. For dural tears >12 mm, we attempted primary closure, considering the anatomical location and margin irregularity, with a fibrin sealant patch used for tears with a regular margin. For tears located in Zone 2 (thecal) and Zone 3 (traversing) with a regular margin, endoscopic closure was performed using a non-penetrating titanium clip (AnastoClip GCⓇ Closure System, Burlington, MA, United States). For large defects in Zone 3, endoscopic closure was attempted using an endoscopic clip with a modified Youn’s technique10 or conversion to microscopic surgery, as needed.
Statistical analysis
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Statistical analyses were performed using R software for Windows (version 3.6.0). Continuous variables (age, physical status, number of surgical levels, and operative time) were compared in patients with and without a dural tear using an unpaired Student’s t-test. Categorical variables (sex and type of surgery) and radiologic grading were compared using a chi-squared test. Depending on the degree of invasiveness, the occurrence of dural tears checked with linear by linear association method. Following invasiveness of procedure, Size of the tear and anatomical zone were compared using a one-way analysis of variance (ANOVA). For all tests, a p-value (two-sided) <0.05 was considered statistically significant.
Results The demographic and pre- and post-operative data for all 643 cases included in our analysis are summarized in Table 1. The number of surgical levels, presence of calcification in the ligamentum flavum and the operative time were the only significant factors related to the occurrence of dural tears (p = 0.03, p <0.01 and p <0.01, respectively).
Intra-operative evaluation Dural tears were identified in 29 of the 643 cases. The anatomical locations of the tears and the treatment outcomes are summarized in Table 2. The operation type did not significantly correlate with dural tearing; the far lateral approach did not result in dural tears; however, the contralateral approach, especially bilateral decompression through unilateral lateral laminotomy (15, 51.7%) showed a relatively high prevalence of dural tears. Zone 1 tears, located at the exiting nerve root, were associated with curettage of a foraminal ligament. The number of tears in the axillary area was lower in Zone 1 than in either of Zones 2 or 3. Zone 2 tears, located in the thecal sac, were associated with the use of an electric drill, or pituitary forceps. This type of tear predominantly occurred during a unilateral approach for bilateral
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decompression using an electric drill, or during epidural fat removal using pituitary forceps. Zone 3 tears, located in the traversing nerve root, were associated with the use of a Kerrison punch. The average dural tear size was 2.5 ± 0.7 mm in Zone 1, 7.1 ± 5.0 mm in Zone 2, and 6.3 ± 4.7 in Zone 3.
Dural tear management Of the 29 patients who sustained a dural tear, 12 were treated by close observation and a 24-h period of absolute bed rest. This management was successful overall, with only one of these 29 patients showing a meningocele after surgery which required re-operation using a PBES technique due to continuous headache. Another 14 patients were treated using a fibrin sealant patch (Fig. 3a, Video 1), followed by a 24-h period of absolute bed rest. The results of this treatment were favorable, without incidence of delayed cerebrospinal fluid (CSF) leakage or need for revision surgery. Another two patients presented with regular margins of the tear which were successfully treated using a non-penetrating titanium clip, via the instrument portal (Fig. 3b, Video 2). A fibrin sealant patch was applied to provide a double layer block. After the procedure, these two patients were treated with a 48-h period of absolute bed rest and in-hospital monitoring, with no incidence of CSF leakage after the procedure. Of the 29 cases of dural tear, only one was treated intra-operatively with conversion to microscopic surgery. After endoscopic or microscopic suturing of the dural tear, patients received the same management technique as patients treated using the titanium clipping method, and all patients recovered without complications. At the 6- and 12-month follow-up, there were no complications related to dural tearing.
Discussion
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All 29 incidental dural tears related to the PBES procedure were treated using endoscopic procedures, except in one patient who required conversion to microscopic surgery. Based on our experience, we have established a treatment algorithm for the management of PBESrelated dural tears (Fig. 4).
The need for suturing Incidental dural tears are common with both microscopic and endoscopic spinal surgery procedures. The best policy for dura tear is prevention. In our series, severe spinal stenosis on MRI did not correlate; however, the presence of calcification significantly correlated with dural tears. We found that the presence of calcifications should guide operative technique and careful procedure. Operative time per level increased in cases of dural tears. We found that operation type did not correlate with dural tearing; however, only 5 cases included the far lateral approach and fusion surgery. If other types of operation are included, results may change as a result of the varying degrees of invasiveness. There are three possible causes of increased operative time: First, multiple adhesion cases require time for dissection; this can increase time and the dural tear rate can increase.11 This can be explained presence of calcification in CT scan correlated to incidence of dural tear. Second, further laminotomy and space preparation for confirmation of tearing margin are needed for diagnosis and management. Third, management time including, sealing with fibrin sealant patch and dura suture is also known cause of increased operative time.12 The other possible factors are surgeon fatigue and the self-fulfilling prophecy for unnecessary treatment. We suggest following size and location of dura tear, physician can make early decision and save operative time. Although the rate of tearing is low overall, for endoscopic procedures, rates of dural tears have been reported as between 0% and 8.6%.1,2 The rate of dura tear in PBES technique
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depends on the surgical learning curve. After 50 cases, the rate of dural tear decreases significantly.13 Dural tears can affect not only the length of hospital stay, but also the rate of re-intervention.14 In our study, an unsuccessful outcome was identified in only one of 29 patients managed with a conservative approach, with revision surgery required due to sustained headache, infection, and pseudomeningocele.15 Primary suturing of the dural tear is regarded as the gold standard treatment for prevention of the development of a pseudomeningocele and continuous CSF leakage.2 Even though endoscopic spinal surgery, including the PBES technique, has advantages, such as less postoperative back pain and early recovery,16 there are drawbacks, such as a relatively limited working space and limited availability of surgical instruments. Therefore, conversion to open microscopic surgery and performance of watertight suturing has traditionally been the accepted standard treatment for endoscopic dural tears. In our study group, 11 of 12 patients with defects <4 mm were treated successfully without intervention. The PBES technique can preserve the posterior muscle and fascia. Preservation of this normal tissue blocks the CSF and can result in more favorable outcomes compared to the conventional invasive method.
Operative misadventures can cause dural tears In our experience, two surgical procedures were common causes of large durotomies and surgical practice related to small dural defect. With curettage, dural tears (mean 9.33 mm) occurred. Incorrect direction of osteotome can cause large dural tears. The edge of the osteotome includes sharp and smooth parts. The sharp part is essential for osteotomy but can cause dural tears. The sharp part of osteotome must always be laterally-directed. Second, unnecessary removal of small particles with pituitary forceps (7.33 mm) can cause large defects. Because of high magnification, small bone ligament and ligament particles must be removed. However, they are usually not symptomatic but rather adhere to dura thereby
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making large longitudinal dural tears. Small dural tears were related to miscellaneous procedure with Kerrison punch (5.7 mm) and drills (5.4 mm). These procedures also required dissection of adhesion before bone and ligament removal.
Microscopic and endoscopic dural tear repair and management Several non-macroscopic procedures for dural closure have been attempted and reported on, including a portal method,10 a muscle and fascia insertion method,17 and a gelform with fibrin sealant patch method.18 With a full endoscopic technique, continuous irrigation creates a liquid form washout, and for this reason, the fibrin glue sealing method cannot be applied in endoscopic surgery.19 The fibrin sealant patch is coated with an outer layer comprising human fibrinogen and thrombin for anticoagulation, and this product was originally designed for hemostasis. This coating easily adheres to the dura, and this is why we use this material instead of fascia and muscle. Furthermore, a closure patch can be designed after measuring the dural defect, which allows sealing of a small defect. However, in some cases, a single patch is not sufficient to achieve a complete seal and application of an additional patch on top of the first is necessary to fully close the area. The successful use of non-penetrating titanium clips has been previously reported, in both in vivo and in vitro experiments,20 and has been applied in trans-sphenoidal endoscopic surgery21 and pediatric neurosurgery.22 In our study, we used non-penetrating titanium clips for closure of relatively large (>1.2 cm) dural tears without CSF leakage. Because this instrument was originally designed for peritoneal repair, portal endoscopic and microendoscopic techniques could not be applied. However, PBES offers the possibility of creating an instrument portal large enough to accommodate this instrument, with the possibility of adjusting the angle during the procedure. However, some defects with irregular margins are not suitable for this procedure, due to the limited instrument control in the dural area. There are several ways and advantages to compensate for
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these shortcomings. First, we can design the working channel flexibly. Free from rigid working canular, various instruments such as large fibrin sealant patch, needle holder and nonpenetrating clip can be applied. Second, stable screen fixing and procedures are possible, independent of the camera. These characteristics are distinct from one-portal endoscopic surgery. Third, depending on experience, one can change the working and instrument ports freely; this can partially compensate for the limitation of endoscopic surgery when one cannot use both hands simultaneously. In our study group, we were able to successfully treat two cases with regular and long dural tears in the thecal sac and the traversing area using a non-penetrating clip, using the PBES technique.
Comparison of biportal technique with one portal and microscopic technique Kambin introduced arthroscopic surgery in 1987, and since then, high definition visualization and surgical tools have become quite advanced, as evidenced by the PBES technique.24 With just a 0.7 cm incision required for the endoscopic portal and the instrumental portal, various surgeries can now be performed using PBES, ranging from discectomy13 to spinal fusion.5 The greatest advantage of PBES, compared to a one-portal technique, is the broad range of instruments that can be used, allowing near-perfect selection of the appropriate instruments for each individual case. Moreover, surgeons can design instrumental portals for cage insertion, non-penetrating clips, and the application of fibrin sealant patches. Compared to microscopic procedures, more detailed visualization and more delicate surgical techniques are also possible using the PBES technique. Furthermore, the possibility of continuous irrigation is helpful for prevention of arachnoiditis or infection. However, bleeding control is relatively harder to achieve with PBES than with a microscopic technique. in addition, the longer operative time required for PBES can be a disadvantage. Specially designed
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penetrating clips, primary suture needle holders, and fibrin sealant insertion instruments may overcome these drawbacks in the near future.
Limitations and scope for future research Several limitations to our research need to be acknowledged. First, we focused on biportal techniques only, so the advantages of uniportal and microscopic procedures were not elucidated. A second limitation was the multicenter design, which meant that different policies for each center may have confounded the outcomes. There are several issues that should be addressed in future studies. In the future, a large, prospective, multicenter study is required that compares uniportal and microscopic endoscopic procedures.
Conclusions In conclusion, in this study, we reported the rate and anatomical location of dural tears associated with biportal endoscopic spinal procedures, and the associated management techniques. We have also demonstrated that intra-operative management and dural closure can provide favorable outcomes without conversion to open surgery. Given that most dural tears were successfully treated using various procedures, we suggest implementation of our management algorithm when physicians encounter cases of incidental dural tear.
Acknowledgments: None. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Disclosure: The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
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8. Schizas C, Theumann N, Burn A, Tansey R, Wardlaw D, Smith FW, Kulik G. Qualitative grading of severity of lumbar spinal stenosis based on the morphology of the dural sac on magnetic resonance images. Spine (Phila Pa 1976). 2010;35:1919–1924. doi: 10.1097/BRS.0b013e3181d359bd. 9. Sato T, Tanaka Y, Aizawa T, Koizumi Y, Kokubun S. Surgical treatment for ossification of ligamentum flavum in the thoracic spine and its complications. Spine Spinal Cord. 10. Shin, JK, Youn, MS, Seong, Y. Iatrogenic dural tear in endoscopic lumbar spinal surgery: full endoscopic dural suture repair (Youn’s technique) Eur Spine J 2018; 27(Suppl 3): 544. https://doi.org/10.1007/s00586-018-5637-6 11. Iyer S, Klineberg EO, Zebala LP, et al. Dural tears in adult deformity surgery: incidence, risk factors, and outcomes. Global Spine J. 2018;8:25–31. doi:10.1177/2192568217717973 12. Kothe R, Quante M, Engler N, Heider F, Kneibl J, Pirchner S, et al. The effect of incidental dural lesions on outcome after decompression surgery for lumbar spinal stenosis: results of a multi-center study with 800 patients. Eur Spine J. 2016;26:2504–2511. https://doi.org/10.1007/s00586-016-4571-8. 13. Kim, W., Kim, S., Kang, S. et al. Pooled analysis of unsuccessful percutaneous biportal endoscopic surgery outcomes from a multi-institutional retrospective cohort of 797 cases. Acta Neurochir. 2019. doi:10.1007/s00701-019-04162-2 14. Saxler G, Kramer J, Barden B, et al. The long-term clinical sequelae of incidental durotomy in lumbar disc surgery. Spine (Phila Pa 1976). 2005;30:2298–2302. 15. Eismont FJ, Wiesel SW, Rothman RH. Treatment of dural tears associated with spinal surgery. J Bone Joint Surg Am. 1981;63:1132–1136.
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Figure legends Fig. 1. Anatomical illustration of dural tear locations Zone 1 = axillar area, Zone 2 = thecal sac area, and Zone 3 = traversing area
Fig. 2. Size estimation of a dural tear The dural tear shown is twice as large as the diameter of the 5-mm hook dissector. Therefore, the size of the dural tear is estimated to be 10 mm. Black arrow = exposed traversing root; yellow arrow = dura tear margin
Fig. 3. Treatment of dural tears (a) A medium-sized dural tear can be sealed using a fibrin sealant patch (yellow arrow), applied using pituitary forceps (black arrow). (b) Regular- and large-sized dural tears (yellow arrow) can be treated using a non-penetrating clip (black arrow).
Fig. 4. Treatment algorithm based on anatomical location and size of the dural tear.
Fig. 5 Preoperative radiologic finding and dura tear. (a) Preoperative magnetic resonance imaging (Loss of nerve strands, Schizas grading C, yellow arrow) was not significantly correlated with dural tear. (b) Computed tomography(Presence of calcification, Sato grading A, yellow arrow) (c) Dura tearing after bilateral decompression through unilateral approach, yellow arrow)
Video legends
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Video 1. Endoscopic fibrin sealant applied to a small dural defect
Video 2. Biportal endoscopic suturing using a non-penetrating titanium clip for a moderate sized dural defect
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Table 1. Baseline clinical data of incidental durotomy during percutaneous biportal endoscopic technique Factors
Total (n = 643)
Incidental durotomy (n = 29)
No durotomy (n = 614)
p-value
Age (years), Mean (SD)
59.1 (12.2)
55.0 (13.2)
59.3 (12.2)
0.06†
Sex, n (%) Male Female
209 (32.5) 434 (67.5)
7 (24.1) 22 (75.9)
202 (32.9) 412 (67.1)
0.29‡
0.11¶
Operation type, n (%) Far lateral approach Ipsilateral approach Contralateral only Bilateral decompression Fusion
5 (0.8) 186 (28.9) 1 (0.2) 442 (68.7) 9 (1.4)
0 (0.0) 13 (44.8) 0 (0.0) 15 (51.7) 1 (3.4)
5 (0.8) 173 (28.2) 1 (0.2) 427 (69.5) 8 (1.3)
ASA-PS (SD)
1.27 (0.5)
1.31 (0.5)
1.28 (0.46)
0.71†
MRI grading
A: 197 (30.6) B: 232 (36.1) C: 172 (26.7) D: 42 (6.53)
A: 9 (31.03) B: 7 (24.1) C: 9 (31.0) D: 4 (13.8)
A: 188 (30.6) B: 225 (36.7) C: 163 (26.5) D: 38 (6.2)
0.11‡
No: 612 A:14 B:16 C:1
No:17 A:8 B:4 C:0
No:600 A:6 B:12 C:1:
>0.01‡*
N of level (%) 1 2 3 4
547 (85.1) 82 (12.8) 8 (1.2) 6 (0.9)
18 (62.1) 10 (34.5) 1 (3.5) 0 (0)
529 (86.2) 72 (11.7) 7 (1.1) 0
Operation time (SD)
63.2 (25.3)
98.3 (37.6)
61.6 (23.4)
CT grading
0.03†*
>0.01†*
†t-test, ‡Pearson’s χ-squared test ¶Linear by linear association SD, standard deviation; ASA-PS, American Society of Anesthesiologists Physical Status; n, number; MRI, Magnetic resonance imaging
Table 2. Anatomical distribution and treatment outcomes Zone 1 (axillary)
Zone 2 (thecal sac)
Zone 3 (traversing)
N (%)
2 (6.9)
18 (62.1)
9 (31.0)
Tearing instrument, n (%) Punch Automated drill Osteotome Curette Forceps
0 (0) 0 (0) 0 (0) 2 (100) 0 (0)
3 (16.7) 5 (27.8) 3 (16.7) 1 (5.6) 6 (33.3)
7 (77.8) 0 (0) 1 (11.1) 1 (11.1) 0 (0)
Size (SD)
2.5 (0.7)
7.1 (5.0)
6.3 (4.7)
Treatment, n (%) Conservative treatment Fibrin sealant patch Nonpenetrating clip Conversion to microscopic surgery
2 (100) 0 (0) 0 (0) 0 (0)
6 (33.3) 10 (55.6) 1 (5.6) 1 (5.6)
4 (44.4) 4 (44.4) 1 (11.1) 0 (0)
0 (0) 0 (0) 0 (0) 0 (0)
2 (11.1) 0 (0) 3 (16.7) 1 (0)
0 (0) 0 (0) 3 (33.3) 0 (0)
Outcomes, n (%) Headache Motor weakness Sensory change Meningocele
p-value
0.45†
†one-way analysis of variance (ANOVA) test SD, standard deviation; n, number
1
Highlights •
We investigated dural tears that occurred during percutaneous biportal surgery (PBES)
•
In 643 cases of PBES, there were 29 dural tears (4.5%)
•
Most dural tears were successfully treated with an endoscopic procedure
•
The incidence of dural tearing was no higher than that for microscopic surgery
•
Our management strategy is effective and safe
Abbreviations: ANOVA one-way analysis of variance CSF cerebrospinal fluid PBES percutaneous biportal endoscopic surgery
1
Jan 10, 2019 Credit Author Statement S-KK had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. H-JP and S-SK designed the study protocol. W-K managed the literature search and summaries of previous related work and wrote the first draft of the manuscript. S-CL and SH provided revisions for intellectual content and final approval of the manuscript. All authors read and approved the final manuscript.
S1878-8750(20)30098-X
DOI:
https://doi.org/10.1016/j.wneu.2020.01.080
Reference:
WNEU 14110
To appear in:
World Neurosurgery
Received Date: 21 October 2019 Revised Date:
10 January 2020
Accepted Date: 11 January 2020
Please cite this article as: Park H-J, Kim S-K, Lee S-c, Kim W, Han S, Kang S-S, Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management, World Neurosurgery (2020), doi: https://doi.org/10.1016/j.wneu.2020.01.080. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2020 Elsevier Inc. All rights reserved.
Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management
Short Title: Management of dural tears in biportal endoscopic spine surgery
Hyun-Jin Park MDa, Seung-Kook Kim, MD, PhDb,c,d*, Su-chan Lee MD, PhDc. Wanseok Kim MDe, Sangho Han MDe, Sang-Soo Kang MDf
a
Department of Spine Center, Orthopaedic Surgery, Hallym University Kangnam Sacred
Heart Hospital, Korea b
Himchan UHS Spine and Joint Centre, Neurosurgery, University Hospital Sharjah,
University street 1, Sharjah 15485, United Arab Emirates c
Joint and Arthritis Research, Orthopaedic Surgery, Himchan Hospital, sinmok-ro 120, Seoul
17999, Korea d
Department of Pharmaceutical Medicine and Regulatory Sciences, College of Medicine and
Pharmacy, Yonsei University, Songdokwahakro 85, Incheon 21983, Korea e
Department of Spine Center, Orthopaedic Surgery, Daechan Hospital, Korea
f
Department of Spine Center, Orthopaedic Surgery, Leaders Hospital, Cheonhodae-ro 1044,
Seoul 05335, Korea
*Corresponding author: Seung-Kook Kim, Himchan UHS Spine and Joint Centre, Neurosurgery, University Hospital of Sharjah, University street 1, Sharjah 15485, United Arab Emirates Tel: +971-6-505-8555; Fax: +971-6-505-8444; E-mail: [email protected]
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Keywords: dural tear, endoscopic spinal surgery, fibrin sealant, nonpenetrating titanium clip, percutaneous biportal endoscopic surgery
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Dural tears in percutaneous biportal endoscopic spine surgery: Anatomical location and management
Abstract Objective: To determine the rate and anatomical location of dural tears associated with spinal surgery using a percutaneous biportal technique (PBES). We aimed to investigate the relationship between dural tears and the type of procedure and type of instrument used.
Methods: We retrospectively analyzed 643 PBES cases by reviewing medical charts, operative records, and operative videos. Incidental durotomy was identified in 29 cases. We analyzed the size and anatomical location of dural tears, as well as the surgical instrument that caused the tear, and the technique used to seal the tear.
Results: The dural tear incidence was 4.5% (29/643 cases). Tears in the exiting nerve area (two cases, 6.9%) were mainly caused by curettage, while tears in the thecal sac area (18 cases, 62.1%) were associated with electric drill and forceps use, and use of a Kerrison punch in the traversing nerve area (nine cases, 31%). Twelve cases of dural tear were treated with in-hospital monitoring and bed rest. Fourteen cases were treated using a fibrin sealant. Two cases were treated with a non-penetrating titanium clip, and one was converted to microscopic surgery. One case of postoperative meningocele after conservative treatment required endoscopic revision surgery to close the dural tear.
Conclusions: Most cases of incidental dural tear during PBES were treated with an endoscopic procedure. The incidence of dural tear was no higher than that was associated
1
with microscopic surgery. Our management strategy for incidental dural tears in biportal endoscopic spinal surgery is safe and effective.
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Introduction Tearing of the dura is a common intra-operative complication of degenerative lumbar surgery, with an incidence of up to 8.6% reported during narrow endoscopic spinal surgery.1,2 Appropriate intra- and post-operative management may improve patient outcomes; however, the length of hospital stay is usually prolonged and patients may experience side-effects.3 The issue of dural tears is clinically meaningful in light of the increased popularity of minimally invasive spinal surgery, which has increased the rate of complications related to spinal surgery.4 Percutaneous biportal endoscopic surgery (PBES) is a variant of endoscopic spinal surgery that provides the benefits of high definition visualization with simple and with simple and fast laminotomy procedure with various instruments. As such, PBES is performed for various spinal conditions, including stenosis decompression, epidural mass removal, and inter-body fusion surgery.5,6 This technique has been associated with favorable outcomes, including early post-operative recovery and shorter length of hospital stay.7 However, PBES-related complications, including dural tears, have not been thoroughly evaluated. Therefore, the purpose of our study was to determine the rate of dural tears associated with PBES spinal surgery, as well as to identify the common location of these tears, and the relationship between dural tears and the type of procedure undertaken, and the type of instruments used. Our secondary aim was to develop a treatment algorithm for dural tears based on our experience.
Materials and methods
Study design and population
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Our retrospective study included prospectively collected data from 643 consecutive patients who underwent PBES for degenerative spinal disease at our institution between May 2016 and June 2018. Our study was approved by our Institutional Review Board (approval Himchan IRB 169684-01-201904-02), and patients provided written informed consent for surgery and the publication of their data. All recorded medical data, surgical records, and endoscopic videos were collected according to the principles of the Declaration of Helsinki. All surgeries were performed by four experienced spinal surgeons, each having more than eight years of experience in performing microscopic and endoscopic spinal procedures. Cases meeting the following criteria were included in our analysis: 1) unilateral decompression laminectomy, including far lateral decompression for foraminal stenosis; 2) unilateral approach for bilateral decompression in cases of central or lateral recess stenosis; 3) unilateral or bilateral discectomy; and 4) fusion surgeries performed using the PBES technique. Excluded were cases of trauma, primary infection, and all other types of microscopic and uniportal endoscopic surgeries.
Diagnosis of dural tear and evaluation Data were reviewed and analyzed by four experienced physicians, each with more than 10 years of experience in the field of spinal surgery. Preoperative demographic data, operation type, medical condition (American Society of Anesthesiologists Physical Status, ASA-PS) and preoperative radiologic MRI grading8 and CT grading9 were evaluated. The procedures are classified according to anatomical contact between dura and instrument as 1) far lateral; 2) ipsilateral 3); contralateral; 4) bilateral decompression through unilateral; and 5) fusion approach. The anatomical location of the dural tear was classified into the following three zones, based on the anatomy of the peripheral nerve at each level (Fig. 1). Zone 1 referred to the dura over the exiting nerve root, and included shoulder lesions under the lower margin of
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the upper pedicle. Zone 2 referred to the path of the thecal sac, but excluded the axilla of the exiting nerve junction and the shoulder of the traversing nerve between the upper and lower pedicle. Zone 3 referred to the traversing nerve root and included the axillar junction with the thecal sac above the upper margin of the lower pedicle. The size of a dural tear was estimated prior to repair using a surgical instrument of specified length, normally a 3-mm Kerrison punch or a 5-mm hook dissector (Fig. 2). Lastly, irregularity of the margins of the tear was verified to determine the possibility of endoscopic closure.
Dural repair and management When a dural tear was identified, those <4 mm in size were treated with a 24-h period of bed rest and in-hospital observation, without any intra-operative intervention. Regarding the need for management, we confirmed the tearing margin with further laminectomy and dissection. Next, we designed the working portal depending on tools, usually requiring 1–2 mm extension of the incision. Dural tears 4–12 mm in size (intermediate size defect) were closed using a fibrin sealant patch (Tachosil , Baxter, Deerfield, IL, United States), followed by close in-hospital observation. For dural tears >12 mm, we attempted primary closure, considering the anatomical location and margin irregularity, with a fibrin sealant patch used for tears with a regular margin. For tears located in Zone 2 (thecal) and Zone 3 (traversing) with a regular margin, endoscopic closure was performed using a non-penetrating titanium clip (AnastoClip GCⓇ Closure System, Burlington, MA, United States). For large defects in Zone 3, endoscopic closure was attempted using an endoscopic clip with a modified Youn’s technique10 or conversion to microscopic surgery, as needed.
Statistical analysis
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Statistical analyses were performed using R software for Windows (version 3.6.0). Continuous variables (age, physical status, number of surgical levels, and operative time) were compared in patients with and without a dural tear using an unpaired Student’s t-test. Categorical variables (sex and type of surgery) and radiologic grading were compared using a chi-squared test. Depending on the degree of invasiveness, the occurrence of dural tears checked with linear by linear association method. Following invasiveness of procedure, Size of the tear and anatomical zone were compared using a one-way analysis of variance (ANOVA). For all tests, a p-value (two-sided) <0.05 was considered statistically significant.
Results The demographic and pre- and post-operative data for all 643 cases included in our analysis are summarized in Table 1. The number of surgical levels, presence of calcification in the ligamentum flavum and the operative time were the only significant factors related to the occurrence of dural tears (p = 0.03, p <0.01 and p <0.01, respectively).
Intra-operative evaluation Dural tears were identified in 29 of the 643 cases. The anatomical locations of the tears and the treatment outcomes are summarized in Table 2. The operation type did not significantly correlate with dural tearing; the far lateral approach did not result in dural tears; however, the contralateral approach, especially bilateral decompression through unilateral lateral laminotomy (15, 51.7%) showed a relatively high prevalence of dural tears. Zone 1 tears, located at the exiting nerve root, were associated with curettage of a foraminal ligament. The number of tears in the axillary area was lower in Zone 1 than in either of Zones 2 or 3. Zone 2 tears, located in the thecal sac, were associated with the use of an electric drill, or pituitary forceps. This type of tear predominantly occurred during a unilateral approach for bilateral
6
decompression using an electric drill, or during epidural fat removal using pituitary forceps. Zone 3 tears, located in the traversing nerve root, were associated with the use of a Kerrison punch. The average dural tear size was 2.5 ± 0.7 mm in Zone 1, 7.1 ± 5.0 mm in Zone 2, and 6.3 ± 4.7 in Zone 3.
Dural tear management Of the 29 patients who sustained a dural tear, 12 were treated by close observation and a 24-h period of absolute bed rest. This management was successful overall, with only one of these 29 patients showing a meningocele after surgery which required re-operation using a PBES technique due to continuous headache. Another 14 patients were treated using a fibrin sealant patch (Fig. 3a, Video 1), followed by a 24-h period of absolute bed rest. The results of this treatment were favorable, without incidence of delayed cerebrospinal fluid (CSF) leakage or need for revision surgery. Another two patients presented with regular margins of the tear which were successfully treated using a non-penetrating titanium clip, via the instrument portal (Fig. 3b, Video 2). A fibrin sealant patch was applied to provide a double layer block. After the procedure, these two patients were treated with a 48-h period of absolute bed rest and in-hospital monitoring, with no incidence of CSF leakage after the procedure. Of the 29 cases of dural tear, only one was treated intra-operatively with conversion to microscopic surgery. After endoscopic or microscopic suturing of the dural tear, patients received the same management technique as patients treated using the titanium clipping method, and all patients recovered without complications. At the 6- and 12-month follow-up, there were no complications related to dural tearing.
Discussion
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All 29 incidental dural tears related to the PBES procedure were treated using endoscopic procedures, except in one patient who required conversion to microscopic surgery. Based on our experience, we have established a treatment algorithm for the management of PBESrelated dural tears (Fig. 4).
The need for suturing Incidental dural tears are common with both microscopic and endoscopic spinal surgery procedures. The best policy for dura tear is prevention. In our series, severe spinal stenosis on MRI did not correlate; however, the presence of calcification significantly correlated with dural tears. We found that the presence of calcifications should guide operative technique and careful procedure. Operative time per level increased in cases of dural tears. We found that operation type did not correlate with dural tearing; however, only 5 cases included the far lateral approach and fusion surgery. If other types of operation are included, results may change as a result of the varying degrees of invasiveness. There are three possible causes of increased operative time: First, multiple adhesion cases require time for dissection; this can increase time and the dural tear rate can increase.11 This can be explained presence of calcification in CT scan correlated to incidence of dural tear. Second, further laminotomy and space preparation for confirmation of tearing margin are needed for diagnosis and management. Third, management time including, sealing with fibrin sealant patch and dura suture is also known cause of increased operative time.12 The other possible factors are surgeon fatigue and the self-fulfilling prophecy for unnecessary treatment. We suggest following size and location of dura tear, physician can make early decision and save operative time. Although the rate of tearing is low overall, for endoscopic procedures, rates of dural tears have been reported as between 0% and 8.6%.1,2 The rate of dura tear in PBES technique
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depends on the surgical learning curve. After 50 cases, the rate of dural tear decreases significantly.13 Dural tears can affect not only the length of hospital stay, but also the rate of re-intervention.14 In our study, an unsuccessful outcome was identified in only one of 29 patients managed with a conservative approach, with revision surgery required due to sustained headache, infection, and pseudomeningocele.15 Primary suturing of the dural tear is regarded as the gold standard treatment for prevention of the development of a pseudomeningocele and continuous CSF leakage.2 Even though endoscopic spinal surgery, including the PBES technique, has advantages, such as less postoperative back pain and early recovery,16 there are drawbacks, such as a relatively limited working space and limited availability of surgical instruments. Therefore, conversion to open microscopic surgery and performance of watertight suturing has traditionally been the accepted standard treatment for endoscopic dural tears. In our study group, 11 of 12 patients with defects <4 mm were treated successfully without intervention. The PBES technique can preserve the posterior muscle and fascia. Preservation of this normal tissue blocks the CSF and can result in more favorable outcomes compared to the conventional invasive method.
Operative misadventures can cause dural tears In our experience, two surgical procedures were common causes of large durotomies and surgical practice related to small dural defect. With curettage, dural tears (mean 9.33 mm) occurred. Incorrect direction of osteotome can cause large dural tears. The edge of the osteotome includes sharp and smooth parts. The sharp part is essential for osteotomy but can cause dural tears. The sharp part of osteotome must always be laterally-directed. Second, unnecessary removal of small particles with pituitary forceps (7.33 mm) can cause large defects. Because of high magnification, small bone ligament and ligament particles must be removed. However, they are usually not symptomatic but rather adhere to dura thereby
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making large longitudinal dural tears. Small dural tears were related to miscellaneous procedure with Kerrison punch (5.7 mm) and drills (5.4 mm). These procedures also required dissection of adhesion before bone and ligament removal.
Microscopic and endoscopic dural tear repair and management Several non-macroscopic procedures for dural closure have been attempted and reported on, including a portal method,10 a muscle and fascia insertion method,17 and a gelform with fibrin sealant patch method.18 With a full endoscopic technique, continuous irrigation creates a liquid form washout, and for this reason, the fibrin glue sealing method cannot be applied in endoscopic surgery.19 The fibrin sealant patch is coated with an outer layer comprising human fibrinogen and thrombin for anticoagulation, and this product was originally designed for hemostasis. This coating easily adheres to the dura, and this is why we use this material instead of fascia and muscle. Furthermore, a closure patch can be designed after measuring the dural defect, which allows sealing of a small defect. However, in some cases, a single patch is not sufficient to achieve a complete seal and application of an additional patch on top of the first is necessary to fully close the area. The successful use of non-penetrating titanium clips has been previously reported, in both in vivo and in vitro experiments,20 and has been applied in trans-sphenoidal endoscopic surgery21 and pediatric neurosurgery.22 In our study, we used non-penetrating titanium clips for closure of relatively large (>1.2 cm) dural tears without CSF leakage. Because this instrument was originally designed for peritoneal repair, portal endoscopic and microendoscopic techniques could not be applied. However, PBES offers the possibility of creating an instrument portal large enough to accommodate this instrument, with the possibility of adjusting the angle during the procedure. However, some defects with irregular margins are not suitable for this procedure, due to the limited instrument control in the dural area. There are several ways and advantages to compensate for
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these shortcomings. First, we can design the working channel flexibly. Free from rigid working canular, various instruments such as large fibrin sealant patch, needle holder and nonpenetrating clip can be applied. Second, stable screen fixing and procedures are possible, independent of the camera. These characteristics are distinct from one-portal endoscopic surgery. Third, depending on experience, one can change the working and instrument ports freely; this can partially compensate for the limitation of endoscopic surgery when one cannot use both hands simultaneously. In our study group, we were able to successfully treat two cases with regular and long dural tears in the thecal sac and the traversing area using a non-penetrating clip, using the PBES technique.
Comparison of biportal technique with one portal and microscopic technique Kambin introduced arthroscopic surgery in 1987, and since then, high definition visualization and surgical tools have become quite advanced, as evidenced by the PBES technique.24 With just a 0.7 cm incision required for the endoscopic portal and the instrumental portal, various surgeries can now be performed using PBES, ranging from discectomy13 to spinal fusion.5 The greatest advantage of PBES, compared to a one-portal technique, is the broad range of instruments that can be used, allowing near-perfect selection of the appropriate instruments for each individual case. Moreover, surgeons can design instrumental portals for cage insertion, non-penetrating clips, and the application of fibrin sealant patches. Compared to microscopic procedures, more detailed visualization and more delicate surgical techniques are also possible using the PBES technique. Furthermore, the possibility of continuous irrigation is helpful for prevention of arachnoiditis or infection. However, bleeding control is relatively harder to achieve with PBES than with a microscopic technique. in addition, the longer operative time required for PBES can be a disadvantage. Specially designed
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penetrating clips, primary suture needle holders, and fibrin sealant insertion instruments may overcome these drawbacks in the near future.
Limitations and scope for future research Several limitations to our research need to be acknowledged. First, we focused on biportal techniques only, so the advantages of uniportal and microscopic procedures were not elucidated. A second limitation was the multicenter design, which meant that different policies for each center may have confounded the outcomes. There are several issues that should be addressed in future studies. In the future, a large, prospective, multicenter study is required that compares uniportal and microscopic endoscopic procedures.
Conclusions In conclusion, in this study, we reported the rate and anatomical location of dural tears associated with biportal endoscopic spinal procedures, and the associated management techniques. We have also demonstrated that intra-operative management and dural closure can provide favorable outcomes without conversion to open surgery. Given that most dural tears were successfully treated using various procedures, we suggest implementation of our management algorithm when physicians encounter cases of incidental dural tear.
Acknowledgments: None. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Disclosure: The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
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8. Schizas C, Theumann N, Burn A, Tansey R, Wardlaw D, Smith FW, Kulik G. Qualitative grading of severity of lumbar spinal stenosis based on the morphology of the dural sac on magnetic resonance images. Spine (Phila Pa 1976). 2010;35:1919–1924. doi: 10.1097/BRS.0b013e3181d359bd. 9. Sato T, Tanaka Y, Aizawa T, Koizumi Y, Kokubun S. Surgical treatment for ossification of ligamentum flavum in the thoracic spine and its complications. Spine Spinal Cord. 10. Shin, JK, Youn, MS, Seong, Y. Iatrogenic dural tear in endoscopic lumbar spinal surgery: full endoscopic dural suture repair (Youn’s technique) Eur Spine J 2018; 27(Suppl 3): 544. https://doi.org/10.1007/s00586-018-5637-6 11. Iyer S, Klineberg EO, Zebala LP, et al. Dural tears in adult deformity surgery: incidence, risk factors, and outcomes. Global Spine J. 2018;8:25–31. doi:10.1177/2192568217717973 12. Kothe R, Quante M, Engler N, Heider F, Kneibl J, Pirchner S, et al. The effect of incidental dural lesions on outcome after decompression surgery for lumbar spinal stenosis: results of a multi-center study with 800 patients. Eur Spine J. 2016;26:2504–2511. https://doi.org/10.1007/s00586-016-4571-8. 13. Kim, W., Kim, S., Kang, S. et al. Pooled analysis of unsuccessful percutaneous biportal endoscopic surgery outcomes from a multi-institutional retrospective cohort of 797 cases. Acta Neurochir. 2019. doi:10.1007/s00701-019-04162-2 14. Saxler G, Kramer J, Barden B, et al. The long-term clinical sequelae of incidental durotomy in lumbar disc surgery. Spine (Phila Pa 1976). 2005;30:2298–2302. 15. Eismont FJ, Wiesel SW, Rothman RH. Treatment of dural tears associated with spinal surgery. J Bone Joint Surg Am. 1981;63:1132–1136.
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16. Kim SK, Kang SS, Hong YH, Park SW, Lee SC. Clinical comparison of unilateral biportal endoscopic technique versus open microdiscectomy for singlelevel lumbar discectomy: a multicenter, retrospective analysis. J Orthop Surg Res. 2018;13:22. https://doi.org/10.1186/s13018-018-0725-1. 17. Oertel JM, Burkhardt BW. Full endoscopic treatment of dural tears in lumbar spine surgery. Eur Spine J. 2017;26:2496–2503. https://doi.org/10.1007/s00586017-5105-8. 18. Ikuta K, Tono O, Tanaka T, Arima J, Nakano S, Sasaki K, et al. Surgical complications of micro-endoscopic procedures for lumbar spinal stenosis. Minim Invasive Neurosurg. 2007;50:145–149. https://doi.org/10.1055/s-2007-985152. 19. Matonick JP, Hammond J. Hemostatic efficacy of EVARREST™, Fibrin Sealant Patch vs. TachoSil® in a heparinized swine spleen incision model. J Invest Surg. 2014;27:360–365. https://doi.org/10.3109/08941939.2014.941444. 20. Ito K, Aoyama T, Horiuchi T, Hongo Z. Utility of nonpenetrating titanium clips for dural closure during spinal surgery to prevent postoperative cerebrospinal fluid leakage. J Neurosurg Spine. 2015;23:812–819. https://doi.org/ 10.3171/2015.3.SPINE141215. 21. Kobayashi H, Asaoka K, Terasaka S, Murata JI. Primary closure of a cerebrospinal fluid fistula by nonpenetrating titanium clips in endoscopic endonasal transsphenoidal surgery: technical note. Skull Base. 2011;21:47–52. https://doi.org/10.1055/s-0030-1263281. 22. Kaufman BA, Matthews AE, Zwienenberg-Lee M, Lew SM. Spinal dural closure with nonpenetrating titanium clips in pediatric neurosurgery. J Neurosurg Pediatr. 2010;6:359–363. https://doi.org/ 10.3171/2010.7.PEDS09545
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23. Kambin P, Brager MD. Percutaneous posterolateral discectomy. Anatomy and mechanism. Clin Orthop Relat Res. 1987;(223):145–154. 24. Lin GX, Huang P, Kotheeranurak V, Park CW, Heo DH, Park CK, et al. A systematic review of unilateral biportal endoscopic spinal surgery: preliminary clinical results and complications. World Neurosurg. 2019;125:425–432. https://doi.org/10.1016/j.wneu.2019.02.038.
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Figure legends Fig. 1. Anatomical illustration of dural tear locations Zone 1 = axillar area, Zone 2 = thecal sac area, and Zone 3 = traversing area
Fig. 2. Size estimation of a dural tear The dural tear shown is twice as large as the diameter of the 5-mm hook dissector. Therefore, the size of the dural tear is estimated to be 10 mm. Black arrow = exposed traversing root; yellow arrow = dura tear margin
Fig. 3. Treatment of dural tears (a) A medium-sized dural tear can be sealed using a fibrin sealant patch (yellow arrow), applied using pituitary forceps (black arrow). (b) Regular- and large-sized dural tears (yellow arrow) can be treated using a non-penetrating clip (black arrow).
Fig. 4. Treatment algorithm based on anatomical location and size of the dural tear.
Fig. 5 Preoperative radiologic finding and dura tear. (a) Preoperative magnetic resonance imaging (Loss of nerve strands, Schizas grading C, yellow arrow) was not significantly correlated with dural tear. (b) Computed tomography(Presence of calcification, Sato grading A, yellow arrow) (c) Dura tearing after bilateral decompression through unilateral approach, yellow arrow)
Video legends
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Video 1. Endoscopic fibrin sealant applied to a small dural defect
Video 2. Biportal endoscopic suturing using a non-penetrating titanium clip for a moderate sized dural defect
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Table 1. Baseline clinical data of incidental durotomy during percutaneous biportal endoscopic technique Factors
Total (n = 643)
Incidental durotomy (n = 29)
No durotomy (n = 614)
p-value
Age (years), Mean (SD)
59.1 (12.2)
55.0 (13.2)
59.3 (12.2)
0.06†
Sex, n (%) Male Female
209 (32.5) 434 (67.5)
7 (24.1) 22 (75.9)
202 (32.9) 412 (67.1)
0.29‡
0.11¶
Operation type, n (%) Far lateral approach Ipsilateral approach Contralateral only Bilateral decompression Fusion
5 (0.8) 186 (28.9) 1 (0.2) 442 (68.7) 9 (1.4)
0 (0.0) 13 (44.8) 0 (0.0) 15 (51.7) 1 (3.4)
5 (0.8) 173 (28.2) 1 (0.2) 427 (69.5) 8 (1.3)
ASA-PS (SD)
1.27 (0.5)
1.31 (0.5)
1.28 (0.46)
0.71†
MRI grading
A: 197 (30.6) B: 232 (36.1) C: 172 (26.7) D: 42 (6.53)
A: 9 (31.03) B: 7 (24.1) C: 9 (31.0) D: 4 (13.8)
A: 188 (30.6) B: 225 (36.7) C: 163 (26.5) D: 38 (6.2)
0.11‡
No: 612 A:14 B:16 C:1
No:17 A:8 B:4 C:0
No:600 A:6 B:12 C:1:
>0.01‡*
N of level (%) 1 2 3 4
547 (85.1) 82 (12.8) 8 (1.2) 6 (0.9)
18 (62.1) 10 (34.5) 1 (3.5) 0 (0)
529 (86.2) 72 (11.7) 7 (1.1) 0
Operation time (SD)
63.2 (25.3)
98.3 (37.6)
61.6 (23.4)
CT grading
0.03†*
>0.01†*
†t-test, ‡Pearson’s χ-squared test ¶Linear by linear association SD, standard deviation; ASA-PS, American Society of Anesthesiologists Physical Status; n, number; MRI, Magnetic resonance imaging
Table 2. Anatomical distribution and treatment outcomes Zone 1 (axillary)
Zone 2 (thecal sac)
Zone 3 (traversing)
N (%)
2 (6.9)
18 (62.1)
9 (31.0)
Tearing instrument, n (%) Punch Automated drill Osteotome Curette Forceps
0 (0) 0 (0) 0 (0) 2 (100) 0 (0)
3 (16.7) 5 (27.8) 3 (16.7) 1 (5.6) 6 (33.3)
7 (77.8) 0 (0) 1 (11.1) 1 (11.1) 0 (0)
Size (SD)
2.5 (0.7)
7.1 (5.0)
6.3 (4.7)
Treatment, n (%) Conservative treatment Fibrin sealant patch Nonpenetrating clip Conversion to microscopic surgery
2 (100) 0 (0) 0 (0) 0 (0)
6 (33.3) 10 (55.6) 1 (5.6) 1 (5.6)
4 (44.4) 4 (44.4) 1 (11.1) 0 (0)
0 (0) 0 (0) 0 (0) 0 (0)
2 (11.1) 0 (0) 3 (16.7) 1 (0)
0 (0) 0 (0) 3 (33.3) 0 (0)
Outcomes, n (%) Headache Motor weakness Sensory change Meningocele
p-value
0.45†
†one-way analysis of variance (ANOVA) test SD, standard deviation; n, number
1
Highlights •
We investigated dural tears that occurred during percutaneous biportal surgery (PBES)
•
In 643 cases of PBES, there were 29 dural tears (4.5%)
•
Most dural tears were successfully treated with an endoscopic procedure
•
The incidence of dural tearing was no higher than that for microscopic surgery
•
Our management strategy is effective and safe
Abbreviations: ANOVA one-way analysis of variance CSF cerebrospinal fluid PBES percutaneous biportal endoscopic surgery
1
Jan 10, 2019 Credit Author Statement S-KK had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. H-JP and S-SK designed the study protocol. W-K managed the literature search and summaries of previous related work and wrote the first draft of the manuscript. S-CL and SH provided revisions for intellectual content and final approval of the manuscript. All authors read and approved the final manuscript.