Spinal tumours constitute about 15 % of all central nervous system tumours1. The tumours arising from the neural tissue, the meninges, the bone, surrounding soft tissue, embryonal rests or as a result of derangement of embryogenesis, or they may spread from other tumours outside the craniospinal axis (metastatic lesions) to the spine are consider as spinal tumour. Spinal tumors can be classified into intramedullary, intradural extramedullary and extradural. They can be either benign or malignant. Tumour arising from intramedullary portion of spinal cord are termed intradural intramedullary (IDIM). Spinal tumour originating outside the intramedullary portion of the spinal cord but inside the dural compartment is termed as intradural extramedullary (IDEM), whereas those arising outside the dura are termed as extradural2. Recent epidemiologic studies have reported an incidence of 0.74 per 100,000 person-years, with an incidence of 0.77 per 100,000 in females and 0.70 per 100,000 in males.3 Primary extradural tumors of the spine are rare and constitute about 4% of all spine tumors.4 Intradural-extramedullary (IDEM) tumors are the most common primary neoplasm in the spine, accounting for approximately 70% of primary spinal tumors5. These lesions occur from within the dura but outside of the parenchyma of spinal cord. Intramedullary tumors arise from the parenchyma of the spinal cord. These tumors account for 20% to 30% of primary spinal neoplasms.6 Spinal cord tumors most commonly occur in the thoracic region, next comes cervical region and tumors in the lumbosacral region are rare. Nerve sheath tumors are the common intradural extramedullary tumors and they constitute 30 % of cases. Meningiomas arises from spinal cord coverings account for nearly 25 %.7 Spinal tumours can be debilitating, posing a significant risk to patient morbidity and mortality. Spinal cord tumors produce a spectrum of signs and symptoms based on the level and plane of lesion which aid in the clinical localization. These may be no specific symptoms. Therefore, most patients are mistakenly diagnosed with cervical spondylopathy, intervertebral disc herniation, metastatic mass, and vascular tumors etc. Although the differential diagnosis of the patient is made by clinical examination and investigations like radiography, vertebral tomography, MRI, and EMG according to the symptoms and findings, IDEM tumors may also be encountered incidentally. Spinal angiography and venography may be needed in some cases especially in recognizing incidentally occurring lesions. Thus, for making the diagnosis of IDEM tumors, taking a detailed history, a through physical examination and performing MRI scans are recommended because the symptoms of IDEM tumors can be similar with those of lumbar herniated nucleus pulposus and spinal stenosis. Magnetic Resonance Imaging (MRI) is the diagnostic modality of choice for spinal tumours. Surgical outcome of spinal tumors varies depending on a number of factors such as site of tumour, rate of growth, extent of cord compression, the histological characteristics of tumour and patient’s age, comorbidity, tumour extension, involvement of neighbouring structures, etc.8 There may be gradual improvement in neurological status with post operative physiotherapy. Treatment options of Spinal tumours are surgery, radiation therapy and chemotherapy depending on histopathology. Majority of the tumours are benign. Intraoperative neurophysiology, high magnification microscopes, ultrasonic aspirators, and intraoperative ultrasound are considered essential aid for the safe resection of spinal cord tumors especially the intramedullary spinal cord tumors (IDIM). Today, with the advancement of early detection and microsurgical techniques, they are considered one of the gratifying parts of neurosurgery.7 In this study, we have reviewed the cases of patients with intradural extramedullary spinal cord tumors (IDEM) treated surgically in our institute by comparing their clinical presentation and radiological finding, their preoperative and postoperative neurological status. A posterior approach was used in all the cases regardless of the location of a tumour in and relative to the spinal cord.

STUDY DESIGN: A prospective observational single centre study. DEFINITION OF POPULATION: Patients attended in Neurosurgery OPD, ward of Calcutta National Medical College and Hospital, Kolkata during the study period of one year from 10/01/23 to 09/01/24 INCLUSION CRITERIA: • Intradural extramedullary spinal tumours. • Age groups between 18 to 60 years old patient. • Patient/patient’s party who has given consent. EXCLUSION CRITERIA: • Patients with illness-limiting surgical interventions were excluded from the study. • Vascular malformations • Infective pathologies including tuberculosis, hydatid cyst, cysticercosis etc. SAMPLE SIZE: 42 cases of IDEM operated during the study periods were included. SAMPLING DESIGN: Samples as per the inclusion criteria was taken during the study period. CONTROL REQUIRED OR NOT: No METHODS OF DATA COLLECTION: METHODOLOGY All the patients attended to Neurosurgery OPD and admitted in neurosurgery Department of this hospital and operated with diagnosis of IDEM as per inclusion criteria stated above was included. The registration data, nature of complaints and duration of symptoms was recorded in proforma. Neurological examination was done. Preoperative functional status was recorded using the Nurick’s grading scales9. A plain and contrast-enhanced MRI spine scan was done during the initial surgical workup. The location of the tumours on sagittal and axial MRI images was recorded preoperatively. Preoperative marker X-ray for confirmation of level in case of thoracic spine was done. Intraoperative use of C-arm was used when required for precise localization of the lesion. In this study, tumour resection with Laminectomy was performed through a posterior approach in all cases. Total excision of tumour with the help of operating microscope was attempted with a goal of preserving neurological function. Posterior spinal fusion in form of transpedicular screw fixation was done in cases where postoperative instability was expected. Closure of the dura mater was performed with 4-0 vicryl with atraumatic round body needle in all cases. Negative pressure drainage was performed in all the cases where bleeding noted. The drain was removed on the second postoperative day. The neurological deficit and the primary functional outcome before and after surgical treatment was assessed by the Nurick’s grading scales9. Physiotherapy (Supported ambulation) and gait training was started on the 3rd postoperative day. Radiological evaluation by contrast MRI of the spine was done post operatively at six months of surgery to assess for adequacy of resection or earlier if indicated. Following surgery, neurological symptoms and physical examinations were recorded in proforma at 2 weeks, at 1 month, at 3 month and at 6 months postoperatively. Patients graded postoperatively on the Nurick’s grading scales at 2-week, 1 month, 3 months and 6 months for the evaluation of functional status. The histopathological report of the tumour was also recorded. Complications of the surgical procedure was recorded. We have defined a "satisfactory improvement" as an improvement in the preoperative Nurick’s grade that have achieved postoperative Nurick’s grade 1 and 0. Patients with an improvement to Nurick’s grade 2 and 3 was labelled as having “partial improvement” and those that have achieved grade 4 and 5 are termed as “no improvement”. The patients who had showed a deterioration of Nurick score will be considered to have a “poor outcome”. Those patients who has no changed in Nurick grade and also has no deteriorations in the symptoms were considered as improvement. Written and Informed consent was obtained from all patients and their first-degree relatives regarding their willingness to be a part of the study and the follow-up process. OPERATIONAL DEFINITIONS IDEM: Tumors that are located within the dural sack but have an arachnoid plane between the tumor and spinal cord. Dumbbell tumors: Tumors that develop an “hourglass” shape as a result of an anatomic barrier encountered during growth with a contiguous intraspinal, foraminal, and/or extraforaminal components. New Neurologic Deficit: Weakness or other neurologic deficit that did not exist before the operation. Worsened Neurologic Deficit: Weakness or another neurologic deficit that existed preop and worsened after surgery. Post-operative infection: Infection of any focus confirmed by laboratory workup or confirmed by the treating the surgeon. Recurrence: Gross total resection confirmed by post-operative MRI and then found to have tumor growth in the same location on follow up. Gross total resection- The operating surgeon’s assessment of all the visible tumors removed and/or postop control imaging showing no visual residual enhancing tumor. Subtotal resection: Operating surgeons’ assessment of visible tumor tissue is left during the surgery or/and residual tumor visible on post-op control imaging Biopsy, when more than 50% of the mass is left. Operative mortality - Any death, regardless of the cause, occurring within 30 days after surgery in or out of the hospital and after 30 days during the same hospitalization subsequent to the operation PARAMETERS STUDIED • Clinical presentation and duration of symptoms. • General examinations • Neurological examination. • Preoperative and postoperative functional status using the Nurick’s grading scale. • A contrast-enhanced MRI of spine • Digital X ray spine AP and Lateral view if necessary • Preoperative Marker X-ray on day of operation with confirmation of level of thoracic spine LABORATORY INVESTIGATIONS: Blood for complete hemogram, ESR, RBS, urea, creatinine, sodium, potassium, serology, thyroid function test, LFT, PT- INR, APTT, chest X-ray PA view, ECG, Special investigations will be done as required. STUDY PERIOD: 1 year STATISTICAL ANALYSIS PLAN: Data was analysed using standard statistical techniques, SPSS (Statistical Package for Social Sciences) version 20.0, Armonk, USA. Graphs and tables were provided.

The study enrolled 42 patients of IDEM as per inclusion and exclusion criteria mentioned in the Materials and Methods section. After data analysis following results were obtained regarding age and sex of presentation • Age distribution and Gender distribution Table: 1: Age distribution pattern and Gender distribution (N=42) AGE(YEARS) NO. OF CASES (%) GENDER (42) ≤ 30 8 (19.04%) Male 19 (45.24%) 31 – 45 15 (35.72%) 46- 59 17 (40.48%) Female 23 (54.76%) ≥60 2 (4.76%) Table 2: Extent of tumour related to number of vertebrae and type of surgery performed EXTENT NUMBER PERCENTAGE (N=42) TYPE OF SURGERY NUMBER PERCENTAGE 1 vertebra 9 21.43 GROSS TOTAL EXCISION 38 90.5 2 vertebrae 24 57.14 3 vertebrae 8 19.05 PARTIAL EXCISION 4 9.5 4 or more levels 1 2.38 More than half of the tumors, 24 cases (57.14%) involved 2 adjacent vertebrae, single-segment lesions were 9(21.43%), 8 (19.05%) lesions involved 3 segments and 1(2.38%) spanned over four or more segments. We had gross total excision in 38 cases (90.5%) where as in 4 (9.5%) cases partial excision was done. Chi-Square Tests Value df Asymp. Sig. (2-sided) Pearson Chi-Square 24.077a 2 .000 Likelihood Ratio 15.224 2 .000 Linear-by-Linear Association 13.484 1 .000 N of Valid Cases 42 a. 4 cells (66.7%) have expected count less than 5. The minimum expected count is .36. P value =0.000 (P value< 0.05). It is statistically significant Table:3: Pre-operative and Post operative Nurick clinical grading (at presentation) (N=42) NURICK GRADE PRE-OPERATIVE NURICK CLINICAL SCALE POST OPERATIVE NURICK CLINICAL SCALE Number Percentage (N=42) Nurick Grade (NG) Number Percentage Grade 0 0 0 Grade I 5 11.9 Satisfactory Improvement (NG 0, 1) 27 64.3 % Grade II 4 9.5 Grade III 8 19.1 Partial Improvement (NG 2,3) 12 28.6 % Grade IV 10 23.8 Grade V 15 35.7 No Improvement (NG 4,5) 3 7.1 % The preoperative nurick clinical scale is presented in above table. Among the 42 patients, 5 (11.9%) graded 1, 4(9.5%) are grade 2, 8 (19.1 %) are grade 3, 10 (23.8%) are grade 4 and 15(35.7 %) are grade 5 In post operative assessment, at 6 months, we have defined a "satisfactory improvement" as an improvement in the preoperative Nurick’s grade that have achieved postoperative Nurick’s grade 1 and 0. Patients with animprovement to Nurick’s grade 2 and 3 was labelled as having“partial improvement” and those that have achieved grade 4 and 5 are termed as “no improvement”. Depicted in above tables no. 3. Chi-Square Test of Preoperative Nurick grade vs Post operative Nurick Grade at 6 months. Chi-Square Tests Value df Asymp. Sig. (2-sided) Pearson Chi-Square 16.372a 8 .037 Likelihood Ratio 20.533 8 .008 Linear-by-Linear Association 10.930 1 .001 N of Valid Cases 42 a. 13 cells (86.7%) have expected count less than 5. The minimum expected count is .36. P value =0.037 (P value< 0.05). It is statistically significant. Table 4: Pathological types of tumours with sex distribution. TYPES OF TUMOURS MALE % N=42 FEMALE % N=42 TOTAL % N=42 MENINGIOMAS 6 14.3 11 26.2 17 40.5 SCHWANNOMAS 5 11.9 9 21.5 14 33.4 NEUROFIBROMAS 3 7.2 1 2.3 4 9.5 EPENDYMOMA 0 0 1 2.3 1 2.3 EPIDERMOID CYST 1 2.3 1 2.3 2 4.6 NEURENTERIC CYST 1 2.3 0 0 1 2.3 DERMOID CYST 1 2.3 0 0 1 2.3 LIPOMA 2 4.8 0 0 2 4.8 In 42 patients, meningioma accounts for 17 cases with a female predominance, female 11 (26.2%) and male 6 (14.3%) followed by 14 (33.4%) patients of schwannoma with female 9(21.5%) and male 5(11.9%), and the third most common group of 4 (14.2%) patients is of neurofibroma of which female 1(2.3%) and male 3(7.2%) patients. Terminal ependymoma comprises of 1(2.3%) case and patient is female 1(2.3%). Epidermoid cyst consists of 2 (4.6%) with 1(2.3%) case each male and female. Neurenteric cyst and dermoid cyst comprises of 1 (2.3%) case each and all them are male patient. Lipoma consists of 2(4.8%) cases and all are male. Table 5: Post-operative complications. Complications Number Percentage No complications 33 78.57 % On foleys catheter 3 7.14 % No improvement in motor power 3 7.14 % CSF Leak 1 2.38 % SSI 1 2.38 % Bed sore 1 2.38 % Total 42 100 % In 9 patients’ complications were observed, most common of which is patients discharged on foleys catheter, 3 patients. 3 patients have no improvement in motor power, 1 patient has CSF leak, 1 has surgical sites infection and other 1 has bed sore.

The laminectomy was the most celebrated surgical case for spinal tumour of Captain Gilbey, who was suffering from tumour of the thoracic spinal cord. Sir Victor Horsley successfully resected the tumour on, June 9, 1887, at the National Hospital, Queens Square, London.10 This is a prospective study conducted with a sample size of 42 patients, operated with diagnosis of IDEM and statistical analysis was done using standard statistical techniques, SPSS (Statistical Package for Social Sciences) version 20.0, Armonk, USA The mean age of peak incidence is 42.64 years. Closer to study conducted by Srinivas et al.11 where means age of occurrence 40.43 years. The gender distribution is 45.24% male and 54.76% females with women predominance. Comparable to study by Narayan et al.13 This result is in line with the theory of IDEM tumour predilection, in which most patients are women. Most common clinical presentation was motor weakness, seen in 36 (85.71%) followed by radicular pain (69.1%), axial neck/back pain (47.62%), sphincter disfunction (54.8%), gait abnormality (54.8%). Comparable to study done by Srinivas et al.11. In our study, mean duration of illness was 9.5 which is comparable to study by Srinivas et al.11. In our study, dorsal region (thoracic) is the most common sites of occurrence of IDEM tumour with 22 cases (52.38%) followed by cervical region has 10 cases (23.80 %) whereas cervicodorsal and lumber regions have same distributions of 5 cases each (11.91%) each. Almost closer to study done by Narayan et al.12. In our study, we have noticed that more than half of the tumors, 24 cases (57.14%) involved 2 adjacent segments of vertebrae, single-segmented lesions were found in 9(21.43%) cases and 3 segments lesions were found in 8 cases (19.05%) and 1(2.38%) case spanned over four or more segments. Almost similar conclusion made by Srinivas et al.11. Microscopic total excision while preserving and improving neurologic function is the usual goal of surgery. All cases were operated through posterior approach and we could perform gross total excision in 38 cases (90.5%) where as in 4 (9.5%) cases partial excision was done. Partial excision was done in view to prevent injury to the spinal cord as total excision was not possible. In 1 case of lumbar IDEM which also has anterolisthesis of L4 over L5, where 3 levels laminectomy was done, needed stabilization by transpedicular fixation. In our study, 5 (11.9%) patients presented with graded 1, 4(9.5%) patients presented with grade 2, 8 (19.1 %) patients are of grade 3, 10(23.8%) patients are of grade 4 and 15(35.7 %) patients have grade 5. The study done by Srinivas et al.11 also has a greater number of patients with poor i.e. Nurick grade 3 and below. In our study, 27 (64.3%) patients have satisfactory outcome while 12 (28.6%) patients have partial improvement and 3 (7.1%) patients have no improvement. Overall improvement in our study is 92.9%. Mean duration of follow up in our study is 6 months. Patient presenting with good Nurick grade has better improvement than those presenting with poor Nurick grading. Srinivas et al.11 also noted that 86 of the 104 (82.6%) patients had a good outcome with a Nurick Grade of 2 or less, 14 (13.7%) patients had a fair outcome while 4 (3.7%) patients had a poor outcome. Their mean follow period is 17 months. In our study, meningioma formed the largest histopathological group with 17 (40.5%%) patients, with female predominance. In study done by A. R. Bhat et al.13 found schwannoma to be most common occurrence followed by meningioma and neurofibroma. In study by Narayan et al.12 nerve sheath tumour was the most common type. In our study, following complications were observed, most common of which is patients discharged on foleys catheter (3 patients). 3 patients have no improvement in motor power, 1 patient has CSF leak, 1 has surgical sites infection and 1 has bed sore. Patient who was discharged on catheter have advised for bladder training which consists of frequent clamping of catheter. No improvement in motor power may be due to nerve injury during excision or due to partial excision because of adhesion and the patient referred to physiotherapist for further management. The use of IONM seeks to alert the surgeon of impending neurological injury before permanent deficits are inflicted. CSF leak was managed successfully with lumbar drain insertion and acetazolamide tablets. Surgical sites infection was managed with regular dressing and use of antibiotic as per cultural sensitivity. Grade 1 bed sore was managed with regular dressing, frequent turning on bed, and advised to use air mattress till lesions is healed. Study conducted by Narayan et al.12 has similar complications CSF leak, surgical site infection, pseudo meningocele etc. 33 patients out of 42 patients needed postoperative physiotherapies in form of passive or active movement of limbs to achieve better functional outcome. Thus, post-operative physiotherapy is the integral part of rehabilitation.

Primary intradural extramedullary (IDEM) tumours of the spinal cord are usually benign. Higher incidence occurs at a mean age of 42.6 years with a female predominance. They usually present with a characteristic motor and sensory symptoms leading to clinical localisation of lesions. Bowel and bladder symptoms are late presentation with duration of illness between 6 months to 1 year (61.90%) with a mean of 9.5 months duration. MRI is the modalities of choice for further delineation of the tumours. In sagittal location, thoracic region is the most common sites of occurrence of IDEM spinal tumours, followed by cervical regions and lumbar region. In axial locations, dorsal to spinal cord is the most common sites of occurrence of IDEM spinal tumour followed by dorsolateral and ventral region. IDEM spinal tumour extending two adjacent vertebrae was the most followed by single level of vertebrae. Most of the patients presented with Nurick grade V followed by grade IV and grade III. Nurick grade II and I are least. Post operative Nurick grade improvement at 2 weeks, 1 month, 2 months and 6 months were better in patients who presented with lower Nurick grade. Patient presented with lower grade has better functional outcome than patient presented with higher grade. Patients with motor weakness achieved better functional outcome with postoperative physiotherapy. Successful removal of an IDEM tumour, complete recovery was achieved in most of the cases with gross total excision done in most of the cases. All cases were approached by a posterior route. In all cases operating microscope (Zeiss carl vario 700) was used and C-arm was used when needed to localise the level of vertebrae. Meningioma accounts for most common incidence of IDEM spinal tumours with schwannomas and neurofibromas to be the next common group. Myxopapillay ependymoma is among the least common occurrence and is found in lumbar region. Epidermoid cyst, lipoma, neurenteric cyst were also among the least common group of occurrences. Few of the complications that has occurred could be managed postoperatively in ward and at home. Thus, IDEM tumours are amenable to microsurgical gross total resection through one-stage posterior approach by laminectomy with the use of operating microscope. IDEM spinal tumours have good functional outcomes irrespective of age, sex, duration of illness or neurological status of patients at presentation. Good clinical and surgical outcome with a higher degree of patient satisfaction can be achieved.

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