The incidence of primary spinal cord tumors in different series was variable. In Asian countries, especially eastern Asia, the frequency of NSCTs is higher than meningiomas. On the other hand, the incidence of meningiomas in western countries (USA and, Europe), is equal to or higher than NSCTs
5. In our series NSCTs, were seen little higher than meningiomas, but no significant difference was determined. The incidances of both types of tumors are close to each other.
According to literature, the male/female ratios for patients with primary spinal cord tumors vary among countries. Briefly, in eastern Asian countries spinal cord tumors predominantly occur in men except menengiomas, whereas in non-Asian countries they predominantly occur in women. Furthermore, a lot of studies from both western and eastern countries, have reported that, spinal meningiomas occur much more frequently in women than in men. The female preponderance for spinal meningiomas is also universal
5. In our current study, we detected; female predominancy for menengiomas, approximately equal ratios for NSCTs, but male predominancy for intramedullary epandimomas and astrocytomas.
In the ligth of the literature, the most common primary spinal cord tumor in patients older than 60 years is meningioma. Ependymomas and schwannomas are more commonly found in middle-aged patients5. For this series, the average age of patients with meningiomas (64.5 years) was significantly higher than that of schwannomas (53 years) and ependymomas (46.5 years).
GTR is the treatment of choice for spinal meningiomas. Surgical treatment of spinal meningiomas has a favorable outcome in the majority of cases. When the tumor resected completely, functional outcome is excellent and recurrence rates are low. Yoon et al. reported the Simpson Grade of resection as a good predictor for recurrence. They emphasized that no recurrent disease seen in their series after Simpson Grade I to III resections6. The most commonly reported sufficient surgical procedure is a singlelevel posterior laminectomy to access the thecal sac and spinal cord for tumor resection; however, laminoplasty or multilevel laminectomy with or without spinal fusion can be other options in suitable cases when necessary. An analysis of 80 patients with spinal meningioma treated surgically with intraoperative monitoring (IOM) by Setzer et al. showed a good outcome with improved or unchanged neurological status in 93.5% of patients. Other studies also showed positive outcomes in over 90% of patients7. Radiotherapy is not a curative treatment for spinal meningiomas; nonetheless, conventional radiotherapy or stereotactic radiosurgery (cyberknife) have been both employed for recurrent meningiomas, large rezidual tumors with atypical or malignant behavior8 .
Schwannomas and / or Neurofibromas (Nerve Sheet Tumors) are slow-growing lesions that arise from the sensory dorsal rootlets in most cases. The majority of lesions are intradural but they can also grow extradurally (10%) or combined intra-extradurally (10–15%). Schwannomas tend to develop an hourglass / dumbell shape due to bony impression at the neural foramen. They present with radicular pain and / or in motor deficits. They are also primarily treated surgically in most cases. The recurrence rate after surgical excision is low. Nerve sheath tumors can be removed effectively due to microsurgical developments. Fernandes et al. reported a GTR rate of 96% and a recurrence rate of 3.3%9. Large tumors with extraforaminal extension may require more extensive approaches and sometimes even stabilization10. In the rare case of intramedullary schwannomas, surgery is the treatment of choice and results in good outcomes if GTR is achieved11. Malignant NSTs are very rare (2.5%). In this study intramedullary schwannoma or neurofibroma and malignant NST were not seen. All of the NSTs were located intradural-extramedullary. Surgery has minimal morbidity, improves symptoms, and may be curative. No adjuvant therapy is recommended and incompletely resected tumors should be followed given the benign growth of the majority of these tumors. Stereotactic radiosurgery is an option for poor surgical candidates 12. Malignant schwannoma should be treated with postoperative radiotherapy, even if total resection was achieved.
Ependymomas are the most frequent IMSCTs in adults13. They are mostly benign tumors (WHO Grade II), which are most likely found in the cervical spine. They are slightly more frequent in males and occur during the 3rd and 6th decade. Histopathologically, ependy-momas can be classified as myxopapillary (WHO grade 1), papillary, cellular, epithelial, and mixed. WHO Grade III intramedullary ependymomas are very rare 14. Cellular (classic) ependymoma arises from the intraspinal canal of the cervical and thoracic cord. Myxopapillary ependymomas arise from the filum terminale and occur almost exclusively at the conus medullaris. The treatment and prognosis for spinal cord ependymomas is often excellent as these tumors may be resected completely and in such instances manifest a low recurrence risk. Ependymomas by MRI appear as a focal enlargement of the cord and hyperintense on T2W and FLAIR images and hypo- or isointense to normal spinal cord on T1W images with heterogeneous contrast enhancement15. These tumors may also be associated with cystic changes, hemosiderin suggestive of previous hemorrhage, and syrinx. Surgery is the most effective treatment with complete surgical resection yielding reported local control rates of 90% to 100%16. Intraoperative monitoring of motor and somatosensory-evoked potentials is often used to assist in achieving a more safe and complete resection17. Even if lower the risk of dissemination, en bloc resection whenever safely possible was recommended 18. Post-operative radiotherapy has been shown to result in superior outcomes for ependymoma: whilst there is general consensus of its benefit in STR, radiotherapy after GTR is contentious19. Especially, WHO grade II ependimomas have a good survey, without RT, if en bloc resection was carried out. Involved- field external beam radiotherapy at a dose of 45 to 54 Gy is indicated and suggested by some authors for partially resected WHO grade 2 ependymomas or malignant WHO grade 3 tumors20. Sgouros et al.21 failed to detect a significant effect of radiotherapy on progression or recurrence, and Tarapore et al.22 identified a negative effect of radiotherapy on survival after STR. There-fore, reoperation in case of the first recurrence should be considered. Radiotherapy may be indicated in case of a repeated STR, thus reducing the long-term risks of radiation myelopathy especially in children and young adults. Chemotherapy for ependymomas outside of a clinical trial is therefore reserved for patients in whom surgery or radiotherapy is not an option or has been previously administered18.
Approximately 40% of IMSCTs are astrocytomas. Astrocytomas develop in childhood or later in adult-hood within the 3rd and 5th decade with a slight male predominance (1.5:1). Their dominant location is the thoracic spine. Spinal astrocytomas in children are mostly benign while those in adults can be more commonly WHO Grade III and IV lesions18. The majo-rity (75%) are lowgrade (WHO grade 2) fibrillary astrocytomas with 5-year survivorship exceeding 70%. Histology is the most important prognostic variable23. High-grade spinal cord gliomas (WHO grades 3 and 4; 25%) are less common and associated with a poor survival. Regardless of WHO grade, spinal cord astrocytomas are infiltrative. Astrocytomas appear on MRI as fusiform expansion of the cord and occasionally a cystic component24. Associated edema or syrinx (seen in 40%) may be present. The tumor is hypo- to isointense on T1W images, hyperintense on T2W and FLAIR images, with variable contrast enhan-cement. In general, the distinction between astrocytomas and ependymomas by magnetic resonance (MR) is not possible25. Initial treatment consists of maximal safe surgical resection or biopsy followed by observation or external beam radiotherapy. Because spinal cord gliomas are infiltrative, gross total resection is rarely accomplished, complete surgical resection is seldom possible and the recurrence rate is as high as 50% over 5 years. Some authors favor biopsy and radiation because surgery carries a risk of neurological deficits and has limited survival benefit even after aggressive resection, but advances in surgical techniques and intraoperative monitoring have improved outcomes26. Tumor histology, extent of resection, and functional status at time of presentation appear to be the primary determinants of outcome27. In general, factors suggestive of need for radiotherapy and/or chemotherapy are higher tumour grade, biopsied-only tumors, and those with progressive disease. At recurrence, radiotherapy is the preferred treatment if not already utilized. Chemotherapy is reserved for patients with progression of disease following surgery and radiotherapy with no other treatment options. Literature regarding chemotherapy for recurrent astrocytomas is extremely limited25. In spinal astrocytomas, histological type is the main prognostic factor for outcome. Tumor histology affects its biological behaviour (WHO grade) as well as the probability of finding a plane of dissection and thereby the potential for GTR (e.g. the behavior of pilocytic astrocytoma versus diffuse astrocytoma)26. Low-grade tumors have low surgery-related complication rates and a good long-term outcome when operated early. In most high-grade tumors, GTR is hardly possible and STR or biopsy followed by radiation and chemotherapy is the recommended standard treatment. Because high grade astrocytomas have more invasive nature than epandimomas18.
Where safe and feasible, GTR is the optimal surgical strategy for IMSCTs due to maximal tumour clearance and lower risk of recurrence. Feasibility of GTR depends on tumour histology and subtype, as well as individual patient anatomy and intra-operative findings. When creating the surgical ‘corridor’ through the spinal cord to access intramedullary tumours, a path that is least destructive to vertical tracts is used. The majority of IMSCT excisions are undertaken via midline myelotomy, which represents the ‘workhorse’ approach due to minimal long-tract disruption and its versatility amongst IMSCTs with a significant central component: in tumours with an eccentric distribution, a number of lateral approaches (e.g. dorsal root entry zone or farlateral) may be used28. We performed midline myelotomy in our all IMSCT cases.
In recent years, IONM has become increasingly important for spinal surgeries, especially in intradural spinal tumors where the risk of spinal cord injury is high18,28. The use IONM did not become routine for all spinal surgeries in the whole world. Also the use of IONM was left to the discretion of the primary surgeon. But some benefits shown for IONM, as it serves to guide the surgeon if there is any early compromise to the spinal cord or nerves and prompts the surgeon to alter his or her technique to prevent worsening neurologic injury. In our results; 34 extramedullary tumor patients were operated with IONM. Only one of these patients had a postoperative worsening of neurological deficit and an increase in neurotic pain. Twenty-five patients with extramedullary tumours underwent sur-gery without IONM. Only one of these patients had worsening neurological deficit and increased neuropathic pain postoperatively. In 8 intramedullary epandimoma patients operated with IONM, and in 6 intramedullary epandimoma patients operated without IONM; we did not see any neurological deterioration and a 100% success was shown. We did not find a significant difference in neurologic outcomes with the use of IONM for excision of intradural extramedullary tumors and intramedullary epandimomas compared with those without IONM. Five intramedullary astrositoma patients were operated with IONM and 4 intramedullary astrositoma patients were operated without IONM. A 60% success rate in IONM group and 50% success rate in non-IONM used patients was achived. These low success rates were due to invasive character of the astrocytomas. According to these results; IONM using may contribute in astrocytomas. IONM can warn the surgeon in the infiltrative parts of the astrocytomas. Also surgeon can be careful in the manuplations of the invasive parts.
This retrospective series showed that good neurologic outcomes and low complication rates after surgery can be achieved in both extramedullary and intramedullary tumors except astrocytomas, especially in high grade astrocytomas. Successfull neuropatic pain and neurologic defisit improvements were not seen in intramedullary astrocytoma patients because of the invasive character of them. Also complete resections of tumors are associated with better outcomes, it is not easy to perform complete excision without causing any neurologic deficit in intramedullary astrocytomas.
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