intramedullary spinal cord tumors ( imscts ) compromise about 2 - 4% of all central nervous system neoplasm and about 20 - 25% of all spinal tumors2,12,35 ) . surgery of imscts is very challenging to neurosurgeons , which may result of devastating neurologic deficit . recently , surgical outcomes of patients with imscts have been improved due to advances of diagnostic imaging , microsurgical technique , surgical equipment , and neurophysiologic monitoring . the purposes of our study were to evaluate the recent surgical outcomes of patients with imsct considering recent advances of diagnostic imaging and surgical technologies . in addition , we analyzed the prognostic factors affecting neurological outcome after surgical resection of imscts . between 1998 and 2013 , 69 patients with an imsct were admitted and underwent surgical treatment at one institution . the post - operative follow up periods were ranged from 6 to 171 month ( mean 34.8 months ) . basic demographic data , clinical presentation and radiologic exams were retrospectively reviewed in each patient . the neurological state was classified according to american spinal injury association ( asia ) grade in order to achieve a grading of functional disturbance of daily life activities and gait disturbances . the neurologic outcome was classified as poor ( a+b ) , fair ( c ) and good ( d+e ) according to the asia grade . patient 's age at diagnosis , sex , histological origin and grade , tumor location , level of tumor extension , pre - operative neurologic state , initial presenting symptoms and extend of tumor resection were reviewed to analyzed prognostic factors . neuroepithelial tumors were classified as low - grade tumors ( gradei+ii ) and high - grade tumors ( grade iii+iv ) by world health organization ( who ) classification . level of tumor extension was classified into less than four involved segments and four or more segments . extend of tumor removals were classified as total resection ( tr ) , subtotal resection ( str ) or biopsy . the tr was defined as complete removal of tumor by microscopic surgical finding and postoperative mri finding . all patients had taken magnetic resonance imaging ( mri ) pre- and post - operatively . few patients were monitored intraoperatively with somatosensory evoked potential ( ssep ) and motor evoked potential ( mep ) . the steroid was prescribed preoperatively in cases with acute neurological deterioration or edematous signs of the surrounding spinal cord tissue in mri . conus medullaris ( n=19 , 27.5% ) and cervical tumors ( n=18 , 26.1% ) were followed . in 38 patients ( 55.1% ) , less than 4 segments were involved and in 31 cases ( 44.9% ) four or more segments were involved . there were forty cases of neuroepithelial tumors ( 58% ) and 29 cases of non - neuroepithelial tumors ( 42% ) . seven patients were diagnosed as a high - grade tumor ( 10.1% ) whereas 62 patients ( 89.9% ) showed low - grade histology . the most common histological origins of imscts was ependymoma ( n=26 , 37.7% ) and astrocytoma ( n=41 , 20.3% ) was followed . the hemangioblastoma ( n=7 , 10.1% ) was most common histological type in non - neuroepithelial tumors ( table 1 ) . in all patients , the neurological outcomes were good in 52 patients ( 75.4% ) , fair in 10 ( 14.5% ) , and poor in 7 ( 10.1% ) . forty seven patients ( 68.1% ) showed the same final neurological states at last follow - up compared to the preoperative neurological state . sixteen patients ( 23.2% ) showed neurological improvement , whereas six patient 's ( 8.7% ) neurological states were aggravated . one patient showed neurological improvement of asia grade a to b , asia grade c to d in four patients and asia grade d to e in 11 patients . however , one patient 's neurological state was aggravated asia grade c to a and 5 patients showed neurological worsening asia grade d to c ( fig . postoperative complications were postoperative hematoma ( 2 ) , csf leakage ( 1 ) , laminoplasty impingement ( 1 ) , and aspiration pneumonia ( 1 ) . in 8 patients , most strong predictive factor for good neurologic outcome after surgery for imscts is a patient 's preoperative neurologic state . patients who can gait dependently or independently ( asia grade d and e ) preoperatively resulted 90.4% of good outcome and 9.6% of fair and poor outcomes . however , patients who can not gait ( asia grade a , b and c ) resulted only 29.4% of good outcome and 70.6% of fair and poor outcomes ( p=0.000 ) . similarly , patient 's with motor weakness showed poor neurological outcome than other symptoms ( p=0.029 ) . relations between pre - operative clinical predictive factors and post - operative neurological outcomes are summarized in table 2 . other predictive factors that affect the neurological outcome are location of tumor ( p=0.011 ) and high grade tumor ( p=0.03 ) . tumors in cervical ( 94.4% ) and conus medullaris ( 88.9% ) lesion result better neurological outcomes than in thoracic ( 59.4% ) lesion . in contrast , poor outcome in higher in thoracic ( 18.8% ) than in cervical ( 0% ) and conus medullaris ( 5.3% ) . high grade tumor shows 42.9% of good outcome and 28.6% of poor outcome , whereas 79% of patients showed good outcome and 8.1% showed poor outcome in low grade tumor . patient 's sex , age ( less or more than 40 years ) , histological origin ( neuroepithelial versus non - neuroepithelial ) , level of tumor extension , and extend of tumor resection ( total resection , subtotal resection or biopsy ) were not associated with postoperative neurological outcome . conus medullaris ( n=19 , 27.5% ) and cervical tumors ( n=18 , 26.1% ) were followed . in 38 patients ( 55.1% ) , less than 4 segments were involved and in 31 cases ( 44.9% ) four or more segments were involved . there were forty cases of neuroepithelial tumors ( 58% ) and 29 cases of non - neuroepithelial tumors ( 42% ) . seven patients were diagnosed as a high - grade tumor ( 10.1% ) whereas 62 patients ( 89.9% ) showed low - grade histology . the most common histological origins of imscts was ependymoma ( n=26 , 37.7% ) and astrocytoma ( n=41 , 20.3% ) was followed . the hemangioblastoma ( n=7 , 10.1% ) was most common histological type in non - neuroepithelial tumors ( table 1 ) . in all patients , the neurological outcomes were good in 52 patients ( 75.4% ) , fair in 10 ( 14.5% ) , and poor in 7 ( 10.1% ) . forty seven patients ( 68.1% ) showed the same final neurological states at last follow - up compared to the preoperative neurological state . sixteen patients ( 23.2% ) showed neurological improvement , whereas six patient 's ( 8.7% ) neurological states were aggravated . one patient showed neurological improvement of asia grade a to b , asia grade c to d in four patients and asia grade d to e in 11 patients . however , one patient 's neurological state was aggravated asia grade c to a and 5 patients showed neurological worsening asia grade d to c ( fig . postoperative complications were postoperative hematoma ( 2 ) , csf leakage ( 1 ) , laminoplasty impingement ( 1 ) , and aspiration pneumonia ( 1 ) . in 8 patients , most strong predictive factor for good neurologic outcome after surgery for imscts is a patient 's preoperative neurologic state . patients who can gait dependently or independently ( asia grade d and e ) preoperatively resulted 90.4% of good outcome and 9.6% of fair and poor outcomes . however , patients who can not gait ( asia grade a , b and c ) resulted only 29.4% of good outcome and 70.6% of fair and poor outcomes ( p=0.000 ) . similarly , patient 's with motor weakness showed poor neurological outcome than other symptoms ( p=0.029 ) . relations between pre - operative clinical predictive factors and post - operative neurological outcomes are summarized in table 2 . other predictive factors that affect the neurological outcome are location of tumor ( p=0.011 ) and high grade tumor ( p=0.03 ) . tumors in cervical ( 94.4% ) and conus medullaris ( 88.9% ) lesion result better neurological outcomes than in thoracic ( 59.4% ) lesion . in contrast , poor outcome in higher in thoracic ( 18.8% ) than in cervical ( 0% ) and conus medullaris ( 5.3% ) . high grade tumor shows 42.9% of good outcome and 28.6% of poor outcome , whereas 79% of patients showed good outcome and 8.1% showed poor outcome in low grade tumor . patient 's sex , age ( less or more than 40 years ) , histological origin ( neuroepithelial versus non - neuroepithelial ) , level of tumor extension , and extend of tumor resection ( total resection , subtotal resection or biopsy ) were not associated with postoperative neurological outcome . in the past , some physicians recommended conservative surgery followed by irradiation for imscts because total removal of tumor may injure normal spinal cord around the tumor34 ) . however , improving medical instruments such as high field mri , surgical tools including microscope with high - definition technology , ultrasonic aspirator and intraoperative monitoring , surgery of imsct has become much safer1 ) . recently , a microsurgical resection is considered as gold standard in the treatment of imsct with the aim of complete tumor removal3 ) . radiotherapy and chemotherapy should only be preserved for high grade lesions or some cases of low grade tumor with incomplete resection and clinical worsening28 ) . although very limited number of cases was done , they suggested that stereotactic radiosurgery is an effective and safe alternative option to conventional radiotherapy . this study shows better outcomes than previous study ( unpublished ) of our institution on imscts . however , 10 ( 23.3 % ) patients showed worsening of functional outcome whereas only 6 patients out of 69 ( 8.7% ) showed neurological worsening in this study . even though improving medical techniques may result better clinical outcome various clinical factors were proposed as predictive factors of functional outcome after imscts surgery . in this study preoperative inability to walk , thoracic location and high - grade tumor were independently associated with poor post - operative functional outcome . patient 's sex , age , histological origin , level of tumor extension and extend of tumor resection were not significantly associated with postoperative functional outcomes in this study . this study also supports the findings of previous reports about predictors about imsct that preoperative ability to walk is the strongest predictive factor of postoperative outcome5,6,9,10,11,13,15,32,33 ) . these results not only emphasize the importance of early recognition of symptoms and evaluations of imsct but also recommend early surgical treatment outcome10,11,13,20,24,25 ) . the operation should be immediately performed not to wait the onset of clinical deterioration to maximize a chance of preserving an ability of walk . furthermore , in our study the tumors in thoracic lesion were associated with poor prognosis ( fig . various studies also showed that tumors arising at thoracic cord were related to poor neurological prognosis1,13,24,33 ) . these could be occurred irreversible damages caused by poor microcirculation and the narrow spinal canal than other spinal lesions during intraoperative maneuver . early surgical interventions should be important in cases with thoracic tumors , even if the neurologic defect is mild . because prolonged compression of imsct , amount of blood flow was increasingly reduced . additionally , thoracic spinal cord had been reported to be more liable to radiation damage18,27 ) , which may be a cause of neurologic defects in survivors with malignancy tumors . on the other hands , tumors located in the thoracic spinal cord take longer time to invade respiratory center leading to respiratory failure ( common cause of death among patients with intramedullary malignancy tumors ) than tumors initially growing from the cervical spinal cord25 ) . high grade tumor tends to infiltrate to normal spinal cord which results obscure surgical plane . removal of high grade tumor may also injured normal spinal cord resulting poor neurological outcome . additionally , high - grade tumors require pre- or post - operative radiotherapy , which could result poor functional outcome38,39 ) . preoperative radiotherapy may cause radiation - induced myelopahty and/or myelitis19 ) and compromise the spinal cord microvasculature which lead to spinal cord ischemia . beside of neurological outcome there are some reports that the patients with glioblastoma had a higher mortality and poor prognosis in malignancy spinal cord tumors21,29,36 ) . the rate of complete resection was approximately 90% for ependymoma and hemangioblastoma and 50 - 76% in low grade astrocytoma11 ) . but adult patients with malignant intramedullary tumors treated with gross total resection had a significantly lower mortality and prognosis than patients treated with subtotal resection , biopsy , or non - surgical measures36 ) . recently , advanced microsurgical skills and intraoperative neurophysiological monitoring have made more aggressive chances for total and nearly total resection of imsct8,17,30 ) . in this study , but several authors reported a series with complete tumor removal and good postoperative functional outcome9,10,22 ) . we did n't found statistical results between extent of tumor resection and neurological outcome , thought that total resection should be tried in low - grade tumors . only in high - grade tumors and the tumors where total removal had not been possible , we suggested partial resection or biopsy with radiotherapies and chemotherapies . neurosurgical advances such as improving neuroimaging , intraoperative neurophysiological monitoring , microsurgical technique , and operative instruments made it possible to achieve total resection of imscts . so neurosurgeons should be having a challenging attitude to total removal of low - grade tumors . the intraoperative neurophysiologic monitoring ( ionm ) , combined recording of sseps and transcranial meps , has become a best material for intraopertative testing of spinal cord function in intramedullary spinal cord tumor surgery7 ) . in many reports showed that imsct surgery with ionm was appeared aggressive removal of imsct and good state of neurologic performance16,23,31 ) . these reports used a combined d - wave ( epidural meps ) and muscular meps ( mmeps ) . hyun et al.14 ) reported that ionm combined sseps and mmeps was good method to prevent irreversible pyramidal tract damage . however , choi et al.4 ) reported that the groups performed operation under sseps and mmeps did n't significantly associate with total excision of tumor and postoperative well neurologic outcomes . in our study , only 7 patients ' operations were performed with ionm combined sseps and mmeps and one patient showed decreased mep during tumor removal . for this reason , it is hard to explain the relationship between the usage of ionm and the neurological outcome in this study . it was necessary that prospective and randomized controlled research to confirm an association between ionm(sseps and mmeps ) and postoperative neurologic outcomes . the recent surgical result of patients with imscts was relatively good with minimal deterioration and complication rate . in addition , imscts in thoracic region showed relatively bad outcome and had a risk of postoperative morbidity compared to that in other regions .