Ahmer Nasir Baig ( Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan. )
Syeda Kubra Kishwar Jafri ( Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan. )
Muhammad Waqas Saeed Baqai ( Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan. )
Muhammad Shahzad Shamim ( Section of Neurosurgery, Department of Surgery, Aga Khan University Hospital, Karachi. )
Primary spinal cord tumours are infrequently encountered CNS neoplasms and can be broadly classified into intradural intramedullary and intradural extramedullary lesions. Resection of these lesions was traditionally done via open surgical access almost always with microscope assistance. With the advent of minimally invasive surgical techniques, endoscopic excision of these lesions has been attempted for selected tumours. Available literature mainly deals with retrospective reviews on small number of patients; therefore, extensive research is required to establish safety and efficacy of endoscopic approach for excision of primary spinal tumours.
Keywords: Spinal tumor, Intramedullary, Intradural, Extramedullary, Minimally invasive spine surgery.
Primary tumours of the spinal cord are uncommon, as compared to the widely encountered metastatic variety.1,2Surgical excision, if possible, is recommended for almost every type of primary spinal tumour, and utility of open and microscopic approaches for this purpose are well established.2 Endoscopic approaches for the resection of such lesions have been considered at some centres due to the minimal invasive nature of the technique, but it still lacks evidence to determine its advantage over microscopic surgery.
Review of Literature
Intrinsic spinal cord tumours account for around 5% to 12% of primary and 2%-5% of all CNS neoplasms.1,3,4These are categorized into the more common intradural extramedullary (70%-90%) and the less common intradural intramedullary subgroups (10%-30%).1,3-5Surgical resection has been established as the primary modality for the diagnosis and treatment of almost all spinal cord tumours.1-3The goal is to decompress the spinal cord by resection of the tumour, preservation of spinal stability and patient's functional status.1,4The choice of surgical route depends on the site and size of lesion, patient characteristics as well as the surgeon’s individual preference.1,4The traditional approach for primary spinal cord tumours is an open surgery which involves posterior midline incision of varying size, subperiosteal paraspinal muscles dissection, laminectomy, with or without facetectomy, tumour resection and spinal fusion if required.6 The introduction of minimally invasive surgery, using a microscope or endoscope aims to provide similar or better surgical outcomes with smaller incisions, better preservation of anatomy, leading to lesser postoperative pain, shorter hospital stay and thus, lower cost.6 The options include microscopic surgery, minimal access endoscopic surgery, neuro-navigation guided spine surgery, percutaneous spine surgery or robotic techniques.7 It must be noted here that endoscopic techniques can only be used in selective patients with small tumours. The goal of surgery is safe and complete excision of tumours, and this goal should not be compromised for the choice of the technique (Figures-1 & 2).
Dhandpani et al., compared the outcomes of micro-endoscopic and pure endoscopic techniques in 34 patients, out of which were 18 nerve sheath tumours, 6 meningiomas, 6 cysts and 6 ependymomas.8 They found no significant difference between these groups. Moreover, the use of expandable ports and sliding technique of delivery was observed to aid removal of large sized tumours which were considered difficult in other reports.8 In a similar study, Zhu et al., evaluated the interlaminar approach for spinal tumour resection.9 They used an endoscope in addition to the microscope for 3 out 15 cases, where the interlaminar space was small and the end of lesion was far away from interlaminar space, for better access and to minimize potential spinal cord damage. Parihar et al., in their retrospective analysis of 18 patients with intradural extramedullary tumours, defined the safety and efficacy of endoscopic technique combined with the use of tubular retractors, to be comparable to microsurgery but with better visualization.6 They also did not report any postoperative CSF leak, infection or spinal instability in their patient population.
Yan et al., in a retrospective study exploring endoscopic surgical techniques via a hemilaminectomy for extramedullary tumors found this approach to be beneficial both in terms of tumour exposure and resection.10 Senturk et al., described favourable outcomes for extramedullary tumours with a translaminar approach, but emphasized on careful patient selection and surgical expertise.11 Neurophysiological monitoring was also described as beneficial to achieve complete removal of anterior intradural tumours in a case report of 2 paediatric cases.12
Review of literature suggested certain advantages of endoscopic approach, including minimal need for traction, preservation of bony, muscular and ligamentous structures and better visualization particularly of the ventral spinal cord and residuals.6,13Other possible merits include, smaller incisions, less tissue trauma, less postoperative pain, less surgical complication, shorter hospital stays and recovery periods and minimal blood loss.7,13Moreover, the use of intraoperative neurophysiological monitoring can prevent excessive manipulation and help to preserve preoperative functional status.2 The major disadvantages of endoscopic approach that were reported include difficulty in attaining watertight dural closure and in case of non-tumour cases, incidental dural tears, both of which may lead to CSF leak and infection.12 Other limitations are difficulty in tumour localization, trouble with manipulation of endoscopic instruments, problems in removing tumours involving more than 2 spinal levels, difficulty with bimanual dissection, difficulty in securing haemostasis and a steep learning curve.6,7Another technical difficulty encountered with endoscopic surgeries especially when dealing with intradural tumours, is dural closure, that greatly discourages neurosurgeons to adopt it.14 Better instruments and availibility of better dural sealants can overcome this limitation.14
There is very little literature available on the pros and cons of endoscopic management of primary spinal cord tumours. At the moment the indication for this technique is limited, although we feel that with growing expertise and confidence of spine surgeons in the use of endoscopes, and with better equipments, more cases will gradually be done endocopically.
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10. Yan X, Wang H, Li C, Lin Y, Lin L, Zhu S,et.al. Endoscopically controlled surgery with open hemilaminectomy for the treatment of intradural extramedullary tumors: an operative technique and short-term outcomes of 20 consecutive cases. Chin. Neurosurg. J.. 2021;7:89-97.
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