- Email: [email protected]
Unexpected Intradural Lumbar Disk Herniation Found During Transforaminal Endoscopic Surgery
Journal Pre-proof An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon, M.D, Moon-Soo Han, M.D, Gwang-Jun Lee, M.D, Seul-Kee Lee, M.D, Bong-Ju Moon, M.D, Jung-Kil Lee, M.D PII:
S1878-8750(19)32961-4
DOI:
https://doi.org/10.1016/j.wneu.2019.11.121
Reference:
WNEU 13790
To appear in:
World Neurosurgery
Received Date: 2 October 2019 Revised Date:
20 November 2019
Accepted Date: 21 November 2019
Please cite this article as: Moon S-J, Han M-S, Lee G-J, Lee S-K, Moon B-J, Lee J-K, An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery., World Neurosurgery (2019), doi: https://doi.org/10.1016/j.wneu.2019.11.121. 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. © 2019 Published by Elsevier Inc.
Case report An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D.
Department of Neurosurgery, Buk-gu Wooridul Spine Hospital, Gwangju, Korea1. Department of Neurosurgery, Chonnam National University Medical School & Research Institute of Medical Sciences, Gwangju, Korea2
Corresponding Author:
Name Jung-Kil Lee, M.D. Address
Department of Neurosurgery
Chonnam National University Hospital 8 Hak-dong, Dong-ku, Gwangju, 501-757 Rep. of Korea Tel
82-62-220-6602
FAX 82-62-224-9865 e-mail [email protected]
Case report An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D.
Department of Neurosurgery, Buk-gu Wooridul Spine Hospital, Gwangju, Korea1. Department of Neurosurgery, Chonnam National University Medical School & Research Institute of Medical Sciences, Gwangju, Korea2
Corresponding Author:
Name Jung-Kil Lee, M.D. Address
Department of Neurosurgery
Chonnam National University Hospital 8 Hak-dong, Dong-ku, Gwangju, 501-757 Rep. of Korea Tel
82-62-220-6602
FAX 82-62-224-9865 e-mail [email protected]
Abstract Background: Intradural disc herniation (IDH) is defined as the displacement of the intervertebral disc nucleus pulposus into the dural sac. In this lumbar lesion, the affected level differs from that of a traditional extradural herniation: 55% of cases occur at the level of L4-5, 16% at L3-4, and 10% at L5-S1. Upper lumbar IDH is extremely rare. We present a case of an IDH at the level of L2-3 that was diagnosed during endoscopic surgery. Case presentation: A 65-year-old male patient presented with severe radiating pain in the anterior right thigh that was accompanied by a tingling sensation in the right calf and difficulty in walking. Physical examination showed normal strength. Bladder and bowel function were normal, but mild hypesthesia of the L3 sensory dermatome was observed. Magnetic resonance imaging (MRI) revealed a herniated disc at the level of L2-L3 that was compressing the right side of the dura. A percutaneous transforaminal endoscopic lumbar discectomy (PELD) was planned. After foraminoplasty, no ruptured disc fragments could be found. During dissection of the adhesion between the dura and protruded disc, the dura was torn. Interestingly, through this dural opening, multiple fragmented disc portions were visualized among the nerve rootlets. We removed some of the soft disc material, however, complete removal of the disc fragments was predicted to damage the rootlets, and we decided to convert to microscopic surgery. The disc fragments were successfully removed via durotomy under microscopic assistance. The incised dorsal dura was primarily sutured with continuous stitches, and the defect on the ventro-lateral side of the dura was patched and sealed using a harvested inner ligamentum flavum and Gelfoam. After the operation, the patient`s symptoms improved. There was no cerebrospinal fluid (CSF) leakage. Conclusion: If there is any preoperative clinical or radiological suspicion of IDH, a microscopic surgical approach should be considered to be the first-line option, as this is a safe and effective method for achieving IDH removal and dura repair without a postoperative neurologic deficit. Even during endoscopic surgery, if the surgeon expects even minor complications, we suggest converting to open surgery. In addition, the adequate sealing of the dura may be sufficient to prevent CSF leakage, without the need for dural suture and lumbar drainage. Key words: Intradural disc herniation, microscopic discectomy, endoscopic discectomy,
Introduction
Intradural disc herniation (IDH) is defined as the displacement of the inter-vertebral disc nucleus pulposus into the dural sac 1. IDH was first reported in 1942 by Dandy 2, and many IDH cases have since been reported in the literature. IDH accounts for between 0.26% and 0.3% of all disc herniation cases, and is more common in males than in females. It occurs most commonly as a lumbar lesion (92%), followed by thoracolumbar (5%) and cervical lesions (3%)
1, 3
. Clinically, there is a higher incidence of cauda equina syndrome (CES) in
IDH than in extradural disc herniation (EDH), due to the direct compression of rootlets within the thecal sac
4, 5
. However, patients typically present with an acute-on-chronic
exacerbation of back pain and radiating pain that does not differ from the presentation of an EDH. Despite the advances in neuroimaging techniques, including computed tomography (CT), myelography and magnetic resonance imaging (MRI), the ability to ascertain preoperatively whether a disc herniation is located intra- or extradurally remains limited 1. Thus, IDH is difficult to diagnose preoperatively. We present a case of IDH at the level of L2-3 that was accidentally discovered via a dural laceration, which occurred during a percutaneous transforaminal endoscopic lumbar discectomy (PELD).
Case presentation
A 65-year-old male patient presented with severe radiating pain in the anterior right thigh, accompanied by a tingling sensation in the right calf and difficulty in walking. Physical examination showed normal strength in both lower extremities. Bladder and bowel function were normal, but mild hypesthesia was observed in the L3 sensory dermatome. MRI revealed a herniated disc at the level of L2-L3 that was compressing the right side of the dura (Figure 1). No calcification or osteophyte formation was observed on CT scan. Based on the physical examination and radiological findings, we diagnosed a ruptured disc in the para-median direction at the level of L2-3 and decided to perform PELD. Under local anesthesia, the patient was placed in the prone position on a radiolucent table. The entry point was 9cm lateral to the midline at the level of the affected disc. After the placement of a working cannula on the posterior annulus of the disc, foraminoplasty was performed in order to secure adequate working space using direct endoscope. During manipulation of the endoscope to search for the disc fragments, no ruptured disc fragment was visualized. Only a protruding disc densely adhering to the dura was found (Figure 2A). We checked the level again and performed meticulous dissection between the dura and the protruding disc, but the dura was torn. Interestingly, through the dural opening, we visualized two disc fragments among the nerve rootlets (Figure 2B) and removed some of the soft disc material. The remnant fragments had a hard, cartilaginous nature and were located between the rootlets (Figure 2C, D). Removing the fragments completely carried the risk of damage to the rootlets, and thus, we decided to convert to microscopic surgery under general anesthesia. An MRI taken immediately postoperatively showed that the disc was partially removed (Figure 3). The day after the first surgery, the patient underwent a microscopic laminectomy and discectomy under general anesthesia. After a wide bilateral laminectomy at the level of L2-L3, the dural sac and roots were exposed. Cerebrospinal fluid (CSF) leakage was observed from the dural opening. Following a dorsal incision of the dura, multiple sequestered disc fragments were found. After removal of the disc fragments, we confirmed a thinned round defect on the ventro-lateral side of the dura, with impaction by the cartilaginous disc material within the defect (Figure 4A). After carefully dissecting the disc material from the surrounding nerve rootlets, the large cartilaginous disc fragment was successfully removed. The incised dorsal dura was primarily sutured with continuous stitches and the defect on ventro-lateral side of the dura was patched and sealed using a harvested
inner ligamentum flavum and Gelfoam (Figure 4B). After the use of the Valsalva maneuver to confirm that no CSF leakage had occurred, fibrin glue was applied. No lumbar drainage was undertaken. The patient’s pain improved postoperatively, and MRI revealed that the IDH had completely resolved. No postoperative CSF leakage occurred, and the patient was subsequently discharged without complications. At a recent follow-up 12 months after the surgery, the patient was asymptomatic.
Discussion
IDH accounts for 0.26% to 0.3% of all disc herniations, and is more common in males than in females 1, 3. In the case of a lumbar lesion, the affected level differs from that of traditional extradural herniation: 55% occur at the level of L4-5, 16% at L3-4, and 10% at L5-S1. Upper lumbar IDH is extremely rare 1. The etiology in these cases is unclear, but the generally accepted hypothesis is that a dense adhesion is present between the ventral aspect of the dura and the posterior longitudinal ligament (PLL), and that the herniated disc fragment acts like a fingertip. Adhesions may occur congenitally due to the formation of a prenatal adhesion, or can be acquired subsequent to degenerative disc disease. The relative movements of the lumbar spine cause repetitive minor trauma of the fixed dural sac that leads to chronic inflammation and erosion, with thinning of the dura. Finally, the PLL and an adherent dura are perforated, and the free disc material can herniate into the dural sac
6-8
. Based on
endoscopic and microscopic findings, this mechanism is considered to be the causative pathology in our case. During the endoscopic surgery, we confirmed dense adhesions of the disc space, PLL, and the dura (Figure 2A). During microscopic surgery, a thinned round defect was found on the ventro-lateral side of the dura, with cartilaginous disc material impacting within the defect (Figure 4A). After releasing the adhesions between the dura and PLL, the impacted disc material could be removed easily through the defect. In addition, IDH can also occur following a previous spinal surgery or trauma due to scar tissue formation within the epidural space 8, 9. A correct preoperative diagnosis of IDH is important for the selection of the correct surgical approach strategy and a favorable prognosis. However, although there is a higher incidence of CES in IDH than in EDH 4, the clinical features do not differ between these lesions. Several radiological findings have been suggested as useful tools for the accurate detection of IDH. Choi et al. 10 suggest that the loss of continuity of the PLL in sagittal images and the “hawkbeak” sign in axial T2 images, which show a triangular aspect of the herniated disc compressed laterally by the cartilaginous edges of the annulus fibrosus, may be associated with IDH. However, even with advanced neuroimaging techniques, there are still limitations in preoperatively determining whether or not a disc herniation is located intradurally 1. For these reasons, IDH is difficult to diagnose preoperatively. In the case presently being reported, there was no definite evidence of IDH based on preoperative MRI or clinical symptoms, and the final diagnosis of IDH was made during endoscopic surgery. Several authors have
described the intra-operative findings that signify a possible IDH: 1) the absence of the expected epidural disc fragments; 2) the spontaneous flow of CSF without intraoperative injury to the dura; 3) difficulty in dissecting the anterolateral portion of the dura from the intervertebral disc 7, 11. These findings are exactly match with our case. Recently, Kim et al.
12
reported a case of IDH that was successfully managed only through
PELD. We also attempted to remove all the disc fragments and repair the dura through PELD; however, the remnant fragments were hard and cartilaginous and located between the nerve rootlets, and thus, the removal carried the risk of causing damage to the rootlets. Therefore, we decided to convert to microscopic surgery in order to completely remove the disc fragments from the thecal sac and repair the dura without complications. Ventral dural repair is technically challenging after a formal durotomy. However, many authors have placed muscle fascia, Gelfoam and a fibrinogen-thrombin patch without suturing the ventral side of the dural defect, and in all cases there was successfully dealt with CSF leakage
9, 12
. In the
case presently being reported, the ventro-lateral dural defect was patched and sealed using a harvested inner ligamentum flavum and Gelfoam (Figure 4B). The patient was asymptomatic and had no CSF leakage 12 months after surgery. Although we did not treat this IDH with PELD only as previously reported 12, we report the appropriate treatment of an IDH through conversion from endoscope surgery to microscopic surgery. We recommend converting to open surgery from endoscopic surgery in the situations listed below. 1) Due to wide dural defect there is not sufficient view to repair dura; 2) disc fragments are hard and cartilaginous nature; 3) difficult to totally remove the disc fragments located between the nerve rootlets.
Conclusion
The preoperative recognition of an IDH is important as it influences the operative strategy. If there is any suspicion of an IDH based on preoperative clinical or radiological clues, a microscopic surgical approach should be considered to be the first-line option. This is considered to be a safe and effective strategy for the removal of an IDH and achieving dura repair without postoperative neurologic deficit. Moreover, during endoscopic surgery, if the surgeon suspects even minor complications, we suggest converting to open surgery. Endoscopic surgery is limited by its proximity to the lesion and does not provide a sufficient view for surgery. In addition, the adequate sealing of the dura may be sufficient to prevent CSF leakage without dural suture and lumbar drainage
Figure Legends Figure 1. Preoperative MRI revealing a herniated disc at the level of L2-L3 compressing the right side of dura. Figure 2. Intraoperative imaging of PELD. (A) Endoscopic view showing formainoplasty and the well-exposed dura. No ruptured disc material was observed in the epidural space. (B) Through the dural laceration, fragmented disc materials were seen (arrow). (C, D) Following the endoscopic removal of two fragments, remnant disc materials (arrow) were visible between the nerve rootlets (arrow head). Figure 3. MRI taken after the PELD demonstrating subtotal removal of the IDH. Figure 4. Intraoperative imaging of microscopic. (A) Following midline durotomy, multiple remnant disc materials were observed between the nerve rootlets. The image shows a dural defect with impacted disc fragments (arrow). (B) The posterior dural incision was closed primarily by using continuous stitches, and the ventro-lateral dural defect was patched and sealed using a harvested inner ligamentum flavum and Gelfoam.
References
1.
D'Andrea G, Trillo G, Roperto R, Celli P, Orlando ER, Ferrante L. Intradural lumbar disc
herniations: the role of MRI in preoperative diagnosis and review of the literature. Neurosurg
Rev. 2004;27(2): 75-80; discussion 81-72. https://doi.org/10.1007/s10143-003-0296-3. 2.
Dandy WE. Recent Advances in the Diagnosis and Treatment of Ruptured Intervertebr
al Disks. Ann Surg. 1942;115(4): 514-520. https://doi.org/10.1097/00000658-194204000-00004. 3.
Kobayashi K, Imagama S, Matsubara Y, et al. Intradural disc herniation: radiographic fi
ndings and surgical results with a literature review. Clin Neurol Neurosurg. 2014;125: 47-51. ht tps://doi.org/10.1016/j.clineuro.2014.06.033. 4.
Singh PK, Shrivastava S, Dulani R, Banode P, Gupta S. Dorsal herniation of cauda equi
na due to sequestrated intradural disc. Asian Spine J. 2012;6(2): 145-147. https://doi.org/10.418 4/asj.2012.6.2.145. 5.
Lee JS, Suh KT. Intradural disc herniation at L5-S1 mimicking an intradural extramedull
ary spinal tumor: a case report. J Korean Med Sci. 2006;21(4): 778-780. https://doi.org/10.3346 /jkms.2006.21.4.778. 6.
Yildizhan A, Pasaoglu A, Okten T, Ekinci N, Aycan K, Aral O. Intradural disc herniation
s pathogenesis, clinical picture, diagnosis and treatment. Acta Neurochir (Wien). 1991;110(3-4): 160-165. https://doi.org/10.1007/bf01400685. 7.
Floeth F, Herdmann J. Chronic dura erosion and intradural lumbar disc herniation: CT
and MR imaging and intraoperative photographs of a transdural sequestrectomy. Eur Spine J. 2012;21 Suppl 4: S453-457. https://doi.org/10.1007/s00586-011-2073-2. 8.
Han IH, Kim KS, Jin BH. Intradural lumbar disc herniations associated with epidural ad
hesion : report of two cases. J Korean Neurosurg Soc. 2009;46(2): 168-171. https://doi.org/10.3 340/jkns.2009.46.2.168. 9.
Jang JW, Lee JK, Seo BR, Kim SH. Traumatic lumbar intradural disc rupture associated
with an adjacent spinal compression fracture. Spine (Phila Pa 1976). 2010;35(15): E726-729. ht tps://doi.org/10.1097/BRS.0b013e3181c64ca7. 10.
Choi JY, Lee WS, Sung KH. Intradural lumbar disc herniation--is it predictable preoper
atively? A report of two cases. Spine J. 2007;7(1): 111-117. https://doi.org/10.1016/j.spinee.2006. 02.025. 11.
Ducati LG, Silva MV, Brandao MM, Romero FR, Zanini MA. Intradural lumbar disc hern
iation: report of five cases with literature review. Eur Spine J. 2013;22 Suppl 3: S404-408. https ://doi.org/10.1007/s00586-012-2516-4. 12.
Kim HS, Pradhan RL, Adsul N, Jang JS, Jang IT, Oh SH. Transforaminal Endoscopic Exci
sion of Intradural Lumbar Disk Herniation and Dural Repair. World Neurosurg. 2018;119: 163-1 67. https://doi.org/10.1016/j.wneu.2018.07.244.
Abbreviations list 1) Intradural disc herniation IDH 2) Magnetic resonance imaging MRI 3) Percutaneous transforaminal endoscopic lumbar discectomy PELD 4) Cerebrospinal fluid CSF 5)
Cauda equina syndrome CES
6) Extradural disc herniation EDH 7) Posterior longitudinal ligament PLL
1
An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D. Conflict : All authors associated with this submission have no financial conflicts of interest to disclose.
S1878-8750(19)32961-4
DOI:
https://doi.org/10.1016/j.wneu.2019.11.121
Reference:
WNEU 13790
To appear in:
World Neurosurgery
Received Date: 2 October 2019 Revised Date:
20 November 2019
Accepted Date: 21 November 2019
Please cite this article as: Moon S-J, Han M-S, Lee G-J, Lee S-K, Moon B-J, Lee J-K, An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery., World Neurosurgery (2019), doi: https://doi.org/10.1016/j.wneu.2019.11.121. 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. © 2019 Published by Elsevier Inc.
Case report An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D.
Department of Neurosurgery, Buk-gu Wooridul Spine Hospital, Gwangju, Korea1. Department of Neurosurgery, Chonnam National University Medical School & Research Institute of Medical Sciences, Gwangju, Korea2
Corresponding Author:
Name Jung-Kil Lee, M.D. Address
Department of Neurosurgery
Chonnam National University Hospital 8 Hak-dong, Dong-ku, Gwangju, 501-757 Rep. of Korea Tel
82-62-220-6602
FAX 82-62-224-9865 e-mail [email protected]
Case report An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D.
Department of Neurosurgery, Buk-gu Wooridul Spine Hospital, Gwangju, Korea1. Department of Neurosurgery, Chonnam National University Medical School & Research Institute of Medical Sciences, Gwangju, Korea2
Corresponding Author:
Name Jung-Kil Lee, M.D. Address
Department of Neurosurgery
Chonnam National University Hospital 8 Hak-dong, Dong-ku, Gwangju, 501-757 Rep. of Korea Tel
82-62-220-6602
FAX 82-62-224-9865 e-mail [email protected]
Abstract Background: Intradural disc herniation (IDH) is defined as the displacement of the intervertebral disc nucleus pulposus into the dural sac. In this lumbar lesion, the affected level differs from that of a traditional extradural herniation: 55% of cases occur at the level of L4-5, 16% at L3-4, and 10% at L5-S1. Upper lumbar IDH is extremely rare. We present a case of an IDH at the level of L2-3 that was diagnosed during endoscopic surgery. Case presentation: A 65-year-old male patient presented with severe radiating pain in the anterior right thigh that was accompanied by a tingling sensation in the right calf and difficulty in walking. Physical examination showed normal strength. Bladder and bowel function were normal, but mild hypesthesia of the L3 sensory dermatome was observed. Magnetic resonance imaging (MRI) revealed a herniated disc at the level of L2-L3 that was compressing the right side of the dura. A percutaneous transforaminal endoscopic lumbar discectomy (PELD) was planned. After foraminoplasty, no ruptured disc fragments could be found. During dissection of the adhesion between the dura and protruded disc, the dura was torn. Interestingly, through this dural opening, multiple fragmented disc portions were visualized among the nerve rootlets. We removed some of the soft disc material, however, complete removal of the disc fragments was predicted to damage the rootlets, and we decided to convert to microscopic surgery. The disc fragments were successfully removed via durotomy under microscopic assistance. The incised dorsal dura was primarily sutured with continuous stitches, and the defect on the ventro-lateral side of the dura was patched and sealed using a harvested inner ligamentum flavum and Gelfoam. After the operation, the patient`s symptoms improved. There was no cerebrospinal fluid (CSF) leakage. Conclusion: If there is any preoperative clinical or radiological suspicion of IDH, a microscopic surgical approach should be considered to be the first-line option, as this is a safe and effective method for achieving IDH removal and dura repair without a postoperative neurologic deficit. Even during endoscopic surgery, if the surgeon expects even minor complications, we suggest converting to open surgery. In addition, the adequate sealing of the dura may be sufficient to prevent CSF leakage, without the need for dural suture and lumbar drainage. Key words: Intradural disc herniation, microscopic discectomy, endoscopic discectomy,
Introduction
Intradural disc herniation (IDH) is defined as the displacement of the inter-vertebral disc nucleus pulposus into the dural sac 1. IDH was first reported in 1942 by Dandy 2, and many IDH cases have since been reported in the literature. IDH accounts for between 0.26% and 0.3% of all disc herniation cases, and is more common in males than in females. It occurs most commonly as a lumbar lesion (92%), followed by thoracolumbar (5%) and cervical lesions (3%)
1, 3
. Clinically, there is a higher incidence of cauda equina syndrome (CES) in
IDH than in extradural disc herniation (EDH), due to the direct compression of rootlets within the thecal sac
4, 5
. However, patients typically present with an acute-on-chronic
exacerbation of back pain and radiating pain that does not differ from the presentation of an EDH. Despite the advances in neuroimaging techniques, including computed tomography (CT), myelography and magnetic resonance imaging (MRI), the ability to ascertain preoperatively whether a disc herniation is located intra- or extradurally remains limited 1. Thus, IDH is difficult to diagnose preoperatively. We present a case of IDH at the level of L2-3 that was accidentally discovered via a dural laceration, which occurred during a percutaneous transforaminal endoscopic lumbar discectomy (PELD).
Case presentation
A 65-year-old male patient presented with severe radiating pain in the anterior right thigh, accompanied by a tingling sensation in the right calf and difficulty in walking. Physical examination showed normal strength in both lower extremities. Bladder and bowel function were normal, but mild hypesthesia was observed in the L3 sensory dermatome. MRI revealed a herniated disc at the level of L2-L3 that was compressing the right side of the dura (Figure 1). No calcification or osteophyte formation was observed on CT scan. Based on the physical examination and radiological findings, we diagnosed a ruptured disc in the para-median direction at the level of L2-3 and decided to perform PELD. Under local anesthesia, the patient was placed in the prone position on a radiolucent table. The entry point was 9cm lateral to the midline at the level of the affected disc. After the placement of a working cannula on the posterior annulus of the disc, foraminoplasty was performed in order to secure adequate working space using direct endoscope. During manipulation of the endoscope to search for the disc fragments, no ruptured disc fragment was visualized. Only a protruding disc densely adhering to the dura was found (Figure 2A). We checked the level again and performed meticulous dissection between the dura and the protruding disc, but the dura was torn. Interestingly, through the dural opening, we visualized two disc fragments among the nerve rootlets (Figure 2B) and removed some of the soft disc material. The remnant fragments had a hard, cartilaginous nature and were located between the rootlets (Figure 2C, D). Removing the fragments completely carried the risk of damage to the rootlets, and thus, we decided to convert to microscopic surgery under general anesthesia. An MRI taken immediately postoperatively showed that the disc was partially removed (Figure 3). The day after the first surgery, the patient underwent a microscopic laminectomy and discectomy under general anesthesia. After a wide bilateral laminectomy at the level of L2-L3, the dural sac and roots were exposed. Cerebrospinal fluid (CSF) leakage was observed from the dural opening. Following a dorsal incision of the dura, multiple sequestered disc fragments were found. After removal of the disc fragments, we confirmed a thinned round defect on the ventro-lateral side of the dura, with impaction by the cartilaginous disc material within the defect (Figure 4A). After carefully dissecting the disc material from the surrounding nerve rootlets, the large cartilaginous disc fragment was successfully removed. The incised dorsal dura was primarily sutured with continuous stitches and the defect on ventro-lateral side of the dura was patched and sealed using a harvested
inner ligamentum flavum and Gelfoam (Figure 4B). After the use of the Valsalva maneuver to confirm that no CSF leakage had occurred, fibrin glue was applied. No lumbar drainage was undertaken. The patient’s pain improved postoperatively, and MRI revealed that the IDH had completely resolved. No postoperative CSF leakage occurred, and the patient was subsequently discharged without complications. At a recent follow-up 12 months after the surgery, the patient was asymptomatic.
Discussion
IDH accounts for 0.26% to 0.3% of all disc herniations, and is more common in males than in females 1, 3. In the case of a lumbar lesion, the affected level differs from that of traditional extradural herniation: 55% occur at the level of L4-5, 16% at L3-4, and 10% at L5-S1. Upper lumbar IDH is extremely rare 1. The etiology in these cases is unclear, but the generally accepted hypothesis is that a dense adhesion is present between the ventral aspect of the dura and the posterior longitudinal ligament (PLL), and that the herniated disc fragment acts like a fingertip. Adhesions may occur congenitally due to the formation of a prenatal adhesion, or can be acquired subsequent to degenerative disc disease. The relative movements of the lumbar spine cause repetitive minor trauma of the fixed dural sac that leads to chronic inflammation and erosion, with thinning of the dura. Finally, the PLL and an adherent dura are perforated, and the free disc material can herniate into the dural sac
6-8
. Based on
endoscopic and microscopic findings, this mechanism is considered to be the causative pathology in our case. During the endoscopic surgery, we confirmed dense adhesions of the disc space, PLL, and the dura (Figure 2A). During microscopic surgery, a thinned round defect was found on the ventro-lateral side of the dura, with cartilaginous disc material impacting within the defect (Figure 4A). After releasing the adhesions between the dura and PLL, the impacted disc material could be removed easily through the defect. In addition, IDH can also occur following a previous spinal surgery or trauma due to scar tissue formation within the epidural space 8, 9. A correct preoperative diagnosis of IDH is important for the selection of the correct surgical approach strategy and a favorable prognosis. However, although there is a higher incidence of CES in IDH than in EDH 4, the clinical features do not differ between these lesions. Several radiological findings have been suggested as useful tools for the accurate detection of IDH. Choi et al. 10 suggest that the loss of continuity of the PLL in sagittal images and the “hawkbeak” sign in axial T2 images, which show a triangular aspect of the herniated disc compressed laterally by the cartilaginous edges of the annulus fibrosus, may be associated with IDH. However, even with advanced neuroimaging techniques, there are still limitations in preoperatively determining whether or not a disc herniation is located intradurally 1. For these reasons, IDH is difficult to diagnose preoperatively. In the case presently being reported, there was no definite evidence of IDH based on preoperative MRI or clinical symptoms, and the final diagnosis of IDH was made during endoscopic surgery. Several authors have
described the intra-operative findings that signify a possible IDH: 1) the absence of the expected epidural disc fragments; 2) the spontaneous flow of CSF without intraoperative injury to the dura; 3) difficulty in dissecting the anterolateral portion of the dura from the intervertebral disc 7, 11. These findings are exactly match with our case. Recently, Kim et al.
12
reported a case of IDH that was successfully managed only through
PELD. We also attempted to remove all the disc fragments and repair the dura through PELD; however, the remnant fragments were hard and cartilaginous and located between the nerve rootlets, and thus, the removal carried the risk of causing damage to the rootlets. Therefore, we decided to convert to microscopic surgery in order to completely remove the disc fragments from the thecal sac and repair the dura without complications. Ventral dural repair is technically challenging after a formal durotomy. However, many authors have placed muscle fascia, Gelfoam and a fibrinogen-thrombin patch without suturing the ventral side of the dural defect, and in all cases there was successfully dealt with CSF leakage
9, 12
. In the
case presently being reported, the ventro-lateral dural defect was patched and sealed using a harvested inner ligamentum flavum and Gelfoam (Figure 4B). The patient was asymptomatic and had no CSF leakage 12 months after surgery. Although we did not treat this IDH with PELD only as previously reported 12, we report the appropriate treatment of an IDH through conversion from endoscope surgery to microscopic surgery. We recommend converting to open surgery from endoscopic surgery in the situations listed below. 1) Due to wide dural defect there is not sufficient view to repair dura; 2) disc fragments are hard and cartilaginous nature; 3) difficult to totally remove the disc fragments located between the nerve rootlets.
Conclusion
The preoperative recognition of an IDH is important as it influences the operative strategy. If there is any suspicion of an IDH based on preoperative clinical or radiological clues, a microscopic surgical approach should be considered to be the first-line option. This is considered to be a safe and effective strategy for the removal of an IDH and achieving dura repair without postoperative neurologic deficit. Moreover, during endoscopic surgery, if the surgeon suspects even minor complications, we suggest converting to open surgery. Endoscopic surgery is limited by its proximity to the lesion and does not provide a sufficient view for surgery. In addition, the adequate sealing of the dura may be sufficient to prevent CSF leakage without dural suture and lumbar drainage
Figure Legends Figure 1. Preoperative MRI revealing a herniated disc at the level of L2-L3 compressing the right side of dura. Figure 2. Intraoperative imaging of PELD. (A) Endoscopic view showing formainoplasty and the well-exposed dura. No ruptured disc material was observed in the epidural space. (B) Through the dural laceration, fragmented disc materials were seen (arrow). (C, D) Following the endoscopic removal of two fragments, remnant disc materials (arrow) were visible between the nerve rootlets (arrow head). Figure 3. MRI taken after the PELD demonstrating subtotal removal of the IDH. Figure 4. Intraoperative imaging of microscopic. (A) Following midline durotomy, multiple remnant disc materials were observed between the nerve rootlets. The image shows a dural defect with impacted disc fragments (arrow). (B) The posterior dural incision was closed primarily by using continuous stitches, and the ventro-lateral dural defect was patched and sealed using a harvested inner ligamentum flavum and Gelfoam.
References
1.
D'Andrea G, Trillo G, Roperto R, Celli P, Orlando ER, Ferrante L. Intradural lumbar disc
herniations: the role of MRI in preoperative diagnosis and review of the literature. Neurosurg
Rev. 2004;27(2): 75-80; discussion 81-72. https://doi.org/10.1007/s10143-003-0296-3. 2.
Dandy WE. Recent Advances in the Diagnosis and Treatment of Ruptured Intervertebr
al Disks. Ann Surg. 1942;115(4): 514-520. https://doi.org/10.1097/00000658-194204000-00004. 3.
Kobayashi K, Imagama S, Matsubara Y, et al. Intradural disc herniation: radiographic fi
ndings and surgical results with a literature review. Clin Neurol Neurosurg. 2014;125: 47-51. ht tps://doi.org/10.1016/j.clineuro.2014.06.033. 4.
Singh PK, Shrivastava S, Dulani R, Banode P, Gupta S. Dorsal herniation of cauda equi
na due to sequestrated intradural disc. Asian Spine J. 2012;6(2): 145-147. https://doi.org/10.418 4/asj.2012.6.2.145. 5.
Lee JS, Suh KT. Intradural disc herniation at L5-S1 mimicking an intradural extramedull
ary spinal tumor: a case report. J Korean Med Sci. 2006;21(4): 778-780. https://doi.org/10.3346 /jkms.2006.21.4.778. 6.
Yildizhan A, Pasaoglu A, Okten T, Ekinci N, Aycan K, Aral O. Intradural disc herniation
s pathogenesis, clinical picture, diagnosis and treatment. Acta Neurochir (Wien). 1991;110(3-4): 160-165. https://doi.org/10.1007/bf01400685. 7.
Floeth F, Herdmann J. Chronic dura erosion and intradural lumbar disc herniation: CT
and MR imaging and intraoperative photographs of a transdural sequestrectomy. Eur Spine J. 2012;21 Suppl 4: S453-457. https://doi.org/10.1007/s00586-011-2073-2. 8.
Han IH, Kim KS, Jin BH. Intradural lumbar disc herniations associated with epidural ad
hesion : report of two cases. J Korean Neurosurg Soc. 2009;46(2): 168-171. https://doi.org/10.3 340/jkns.2009.46.2.168. 9.
Jang JW, Lee JK, Seo BR, Kim SH. Traumatic lumbar intradural disc rupture associated
with an adjacent spinal compression fracture. Spine (Phila Pa 1976). 2010;35(15): E726-729. ht tps://doi.org/10.1097/BRS.0b013e3181c64ca7. 10.
Choi JY, Lee WS, Sung KH. Intradural lumbar disc herniation--is it predictable preoper
atively? A report of two cases. Spine J. 2007;7(1): 111-117. https://doi.org/10.1016/j.spinee.2006. 02.025. 11.
Ducati LG, Silva MV, Brandao MM, Romero FR, Zanini MA. Intradural lumbar disc hern
iation: report of five cases with literature review. Eur Spine J. 2013;22 Suppl 3: S404-408. https ://doi.org/10.1007/s00586-012-2516-4. 12.
Kim HS, Pradhan RL, Adsul N, Jang JS, Jang IT, Oh SH. Transforaminal Endoscopic Exci
sion of Intradural Lumbar Disk Herniation and Dural Repair. World Neurosurg. 2018;119: 163-1 67. https://doi.org/10.1016/j.wneu.2018.07.244.
Abbreviations list 1) Intradural disc herniation IDH 2) Magnetic resonance imaging MRI 3) Percutaneous transforaminal endoscopic lumbar discectomy PELD 4) Cerebrospinal fluid CSF 5)
Cauda equina syndrome CES
6) Extradural disc herniation EDH 7) Posterior longitudinal ligament PLL
1
An unexpected intradural lumbar disc herniation found during transforaminal endoscopic surgery. Sung-Jun Moon1, M.D., Moon-Soo Han2, M.D., Gwang-Jun Lee2, M.D., Seul-Kee Lee2, M.D., Bong-Ju Moon2, M.D., Jung-Kil Lee2, M.D. Conflict : All authors associated with this submission have no financial conflicts of interest to disclose.