Clinical and pathological outcomes after resection of intramedullary spinal cord tumors: a single-institution case series

Neurological Outcome of Spinal Hemangioblastomas: An International Observational Multicenter Study About 35 Surgical Cases

INTRODUCTION

Hemangioblastomas (HBs) are benign, highly vascular tumors that can be found intracranially or in the spinal region, representing around 2-15% of primary intramedullary tumors. They can occur sporadically or in association with Von Hipple-Lindau (VHL) disease. Despite recent of advancement of nonsurgical treatments, complete surgical resection remains the gold standard of care for the spinal HBs.

MATERIALS AND METHODS

We conducted an international multicenter retrospective analysis of adult patients surgically treated for spinal HBs in four European referral centers between January 2000 and September 2024, with a minimum post-operative follow-up duration of 6 months. Patients' sex and age at surgical intervention, clinical presentation, and duration symptoms prior to clinical diagnosis were identified. The pre- and post-operative neurological status at 1 and 6 months and at the last visit was assessed using the modified McCormick score (MCS). The extent of surgical resection was divided into gross total resection (GTR) and subtotal resection (STR). Finally, post-operative complications were inspected as well, namely cerebrospinal fluid leaks, infections, hemorrhages and post-operative spinal stability.

RESULTS

A total of 35 patients were included in the cohort, with an age median of 52 years (34.5-60) and a slight male predominance (21/35, i.e., 60%). The median follow-up period was 37.5 months (12-75). More than half were located in the cervical region, making it the most common (54.3%). Syrinxes were observed in 23 cases (72%), and HBs were more commonly intramedullary (80%). GTR was achievable in around 88% of cases. Post-operative complications were observed in nine patients (25.7%). Nearly half of patients were discharged into rehabilitations centers (48.5%). Tumor recurrence was seen in 10.3% only. At the last follow-up, an excellent overall post-operative neurological status (positive ∆ McCormick) was observed in most of patients (88%) and was found to be associated with a relatively younger age group. Tumor location and presence of syrinxes did not show any statistical significance regarding clinical outcome. In patients having benefited from intra-operative monitoring, only D-wave changes showed statistical significance regarding post-operative outcome (p < 0.05).

CONCLUSIONS

A large majority of patients operated for a spinal HB demonstrated favorable outcome after surgery, with unchanged or improved neurological status. Advanced age could have an impact on the post-operative neurological outcome. Other factors such as tumor size, location, and the presence of syrinx did not seem to significantly impact the neurological outcome. Finally, the surgery of these vascular lesions with no possibility of debulking or piece-meal removal and requiring "en bloc" resection is technically demanding and should be performed by experienced teams in spine and spinal cord surgery only.

Disease characteristics and clinical specific survival prediction of spinal ependymoma: a genetic and population-based study

Background

Spinal Ependymoma (SP-EP) is the most commonly occurring tumor affecting the spinal cord. Prompt diagnosis and treatment can significantly enhance prognostic outcomes for patients. In this study, we conducted a comprehensive analysis of RNA sequencing data, along with associated clinical information, from patients diagnosed with SP-EP. The aim was to identify key genes that are characteristic of the disease and develop a survival-related nomogram.

Methods

We first accessed the Gene Expression Integrated Database (GEO) to acquire the microarray dataset pertaining to SP-EP. This dataset was then processed to identify differentially expressed genes (DEGs) between SP-EP samples and normal controls. Furthermore, machine learning techniques and the CIBERSORT algorithm were employed to extract immune characteristic genes specific to SP-EP patients, thereby enhancing the characterization of target genes. Next, we retrieved comprehensive information on patients diagnosed with SP-EP between 2000 and 2020 from the Surveillance, Epidemiology, and End Results Database (SEER). Using this data, we screened for predictive factors that have a significant impact on patient outcomes. A nomogram was constructed to visualize the predicted overall survival (OS) rates of these patients at 3, 5, and 8 years post-diagnosis. Finally, to assess the reliability and clinical utility of our predictive model, we evaluated it using various metrics including the consistency index (C-index), time-dependent receiver operating characteristic (ROC) curves, area under the curve (AUC), calibration curves, and decision curve analysis (DCA).

Results

A total of 5,151 DEGs were identified between the SP-EP sample and the normal sample. Analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways revealed that these DEGs were primarily involved in cellular processes, including cell cycle regulation and cell sensitivity mechanisms. Furthermore, immune infiltration analysis was utilized to identify the core gene CELF4. Regarding the survival rates of patients with SP-EP, the 3-year, 5-year, and 8-year survival rates were 72.5, 57.0, and 40.8%, respectively. Diagnostic age (p < 0.001), gender (p < 0.001), and surgical approach (p < 0.005) were identified as independent prognostic factors for OS. Additionally, a nomogram model was constructed based on these prognostic factors, demonstrating good consistency between predicted and actual results in the study's validation process. Notably, the study also demonstrated that more extensive surgical resection could extend patients' OS.

Conclusion

Through bioinformatics analysis of microarray datasets, we identified CELF4 as a central gene associated with immune infiltration among DEGs. Previous studies have demonstrated that CELF4 may play a pivotal role in the pathogenesis of SP-EP. Furthermore, this study developed and validated a prognostic prediction model in the form of a nomogram utilizing the SEER database, enabling clinicians to accurately assess treatment risks and benefits, thereby enhancing personalized therapeutic strategies and prognosis predictions.

What Factors Predict the Development of Neurologic Deficits Following Resection of Intramedullary Spinal Cord Tumors: A Multi-Center Study

BACKGROUND

Intramedullary spinal cord tumors are challenging to resect, and their postoperative neurological outcomes are often difficult to predict, with few studies assessing this outcome.

METHODS

We reviewed the medical records of all patients surgically treated for Intramedullary spinal cord tumors at our multisite tertiary care institution (Mayo Clinic Arizona, Mayo Clinic Florida, Mayo Clinic Rochester) between June 2002 and May 2020. Variables that were significant in the univariate analyses were included in a multivariate logistic regression. "MissForest" operating on the Random Forest algorithm, was used for data imputation, and K-prototype was used for data clustering. Heatmaps were added to show correlations between postoperative neurological deficit and all other included variables. Shapley Additive exPlanations were implemented to understand each feature's importance.

RESULTS

Our query resulted in 315 patients, with 160 meeting the inclusion criteria. There were 53 patients with astrocytoma, 66 with ependymoma, and 41 with hemangioblastoma. The mean age (standard deviation) was 42.3 (17.5), and 48.1% of patients were women (n = 77/160). Multivariate analysis revealed that pathologic grade >3 (OR = 1.55; CI = [0.67, 3.58], P = 0.046 predicted a new neurological deficit. Random Forest algorithm (supervised machine learning) found age, use of neuromonitoring, histology of the tumor, performing a midline myelotomy, and tumor location to be the most important predictors of new postoperative neurological deficits.

CONCLUSIONS

Tumor grade/histology, age, use of neuromonitoring, and myelotomy type appeared to be most predictive of postoperative neurological deficits. These results can be used to better inform patients of perioperative risk.

Effect of race, sex, and socioeconomic factors on overall survival following the resection of intramedullary spinal cord tumors

INTRODUCTION

Intramedullary spinal cord tumors (IMSCTs) account for 2-4% of all primary CNS tumors. Given their low prevalence and the intricacy of their diagnosis and management, it is critical to address the surrounding racial and socioeconomic factors that impact the care of patients with IMSCTs. This study aimed to investigate the association between race and socioeconomic factors with overall 5 year mortality following the resection of IMSCTs.

METHODS

The study used the National Cancer Database to retrospectively analyze patients who underwent resection of IMSCTs from 2004 to 2017. Patients were divided into four cohorts by race/ethnicity, facility type, insurance, median income quartiles, and living area. The primary outcome of interest was 5 year survival, and secondary outcomes included postoperative length of stay and 30 day readmission. Descriptive and multivariable analyses were used to identify independent factors associated with mortality, with statistical significance assessed at a 2-sided p < 0.05.

RESULTS

We evaluated the patient characteristics and outcomes for 8,028 patients who underwent surgical treatment for IMSCTs between 2004 and 2017. Most patients were white males (52.4%) with a mean age of 44 years where 7.17% of patients were Black, 7.6% were Hispanic, and 3% were Asian. Most were treated in an academic/research program (72.4%) and had private insurance (69.2%). Black patients had a higher odd of 5 year mortality (OR 1.4; 95% CI 1.1 to 1.77; p = 0.04) compared to white patients, while no significant differences in mortality were observed among other races. Factors associated with lower odds of mortality included being female (OR 0.89; 95% CI 0.78 to 1.02; p < 0.01), receiving treatment in an academic/research program (OR 0.51; 95% CI 0.33 to 0.79; p = 0.04), having private insurance (OR 0.65; 95% CI 0.45 to 0.93; p = 0.02), and having higher income quartiles (OR 0.77; 95% CI 0.62 to 0.96; p = 0.02).

CONCLUSION

Our study sheds light on the healthcare disparities that exist in the surgical management of IMSCTs. Our findings indicate that race, sex, socioeconomic status, and treatment facility are independent predictors of 5 year mortality, with Black patients, males, those with lower socioeconomic status, and those treated at non-academic centers experiencing significantly higher mortality rates. These alarming disparities underscore the urgent need for policymakers and researchers to address the underlying factors contributing to these discrepancies and provide equal access to high-quality surgical care for patients with IMSCTs.

Spinal oncologic paraparesis: Analysis of neurological and surgical outcomes in patients with intramedullary, extramedullary, and extradural tumors

Objectives

Paraparesis due to oncologic lesions of the spine warrants swift neurosurgical intervention to prevent permanent disability and hence maintain independence of affected patients. Clinical parameters that predict a favorable outcome after surgical intervention could aid decision-making in emergency situations.

Methods

Patients who underwent surgical intervention for paraparesis (grade of muscle strength <5 according to the British Medical Research Council grading system) secondary to spinal neoplasms between 2006 and 2020 were included in a single-center retrospective analysis. Pre- and postoperative clinical data were collected. The neurological status was assessed using the modified McCormick Disability Scale (mMcC) Score. In a univariate analysis, patients with favorable (discharge mMcC improved or stable at <3) and non-favorable outcome (discharge mMcC deteriorated or stable at >2) and different tumor anatomical compartments were statistically compared.

Results

117 patients with oncologic paraparesis pertaining to intramedullary lesions (n=17, 15%), intradural extramedullary (n=24, 21%) and extradural lesions (n=76, 65%) with a mean age of 65.3 ± 14.6 years were included in the analysis. Thoracic tumors were the most common (77%), followed by lumbar and cervical tumors (13% and 12%, respectively). Surgery was performed within a mean of 36±60 hours of admission across all tumors and included decompression over a median of 2 segments (IQR:1-3) and mostly subtotal tumor resection (n=83, 71%). Surgical and medical complications were documented in 9% (n=11) and 7% (n=8) of cases, respectively. The median hospital length-of-stay was 9 (7-13) days. Upon discharge, the median mMcC score had improved from 3 to 2 (p<0.0001). At last follow-up (median 180; IQR 51-1080 days), patients showed an improvement in their mean Karnofsky Performance Score (KPS) from 51.7±18.8% to 65.3±20.4% (p<0.001). Localization in the intramedullary compartment, a high preoperative mMcC score, in addition to bladder and bowel dysfunction were associated with a non-favorable outcome (p<0.001).

Conclusion

The data presented on patients with spinal oncologic paraparesis provide a risk-benefit narrative that favors surgical intervention across all etiologies. At the same time, they outline clinical factors that confer a less-favorable outcome like intramedullary tumor localization, a high McCormick score and/or bladder and bowel abnormalities at admission.

Long-term quality of life and functional outcomes in adults surgically treated for intramedullary spinal cord tumor

Introduction

Intramedullary spinal cord tumors (IMSCTs) are rare but clinically significant entities that may cause severe neurological decline with progressive pain and motor or sensory deterioration. Beyond the beneficial effects of surgical treatment and the long-term progression-free survival, neurological deficits may still persist after surgery, and information about the long-term patients' health-related quality of life (QoL) is still lacking. In this study, we investigate the patients' health perception 15 years after the surgery in an overall patients' wellbeing framework.

Methods

Patients surgically treated for IMSCT over a period from 1996 to 2011 were selected. After a mean of 15 years from the surgery, patient's self-administered questionnaire on disability, pain, sleep quality, and QoL was collected and neurological postoperative evaluation at the chronic stage was reexamined.

Results

Neurological deficits are reported in half of the patients in the postoperative chronic phase. After 15 years of surgery, half of the patients still report mild or severe disability grades associated with significantly higher pain and poor sleep and QoL. In accordance, the neurological condition measured at the chronic stage is significantly related not only to disease-specific symptoms (i.e., pain) but even to sleep quality complaints and poor QoL, measured at 15 years follow-up.

Conclusions

Health-related QoL is an important secondary outcome in patients. Although the progression-free survival, worse postoperative neurological conditions could predict long-term sequelae reflecting patients' poor health perception. It suggests the importance of preserving patients' functional status and globally evaluating patients' wellbeing to handle disease-specific symptoms but even more general aspects of QoL.

Primary Spinal Cord Astrocytomas: Two-Center Clinical Experience of Low- and High-Grade Lesions

OBJECTIVE

Primary spinal cord astrocytomas are rare, fatal, and poorly studied.

METHODS

This study included a 2-center, retrospective analysis of primary spinal cord astrocytoma patients from 1997 to 2020. Patients with drop metastases or without at least one follow-up were excluded.

RESULTS

Seven World Health Organization grade I, 6 grade II, 7 grade III, and 4 grade IV astrocytoma patients were included. Older patients had higher grades (median 20 years in grade I vs. 36.5 in grade IV). The median follow-up was 15 months. Thirteen patients were discharged to rehabilitation. Eight patients demonstrated radiographic progression. Adjuvant therapy was utilized more in higher grades (5 of 13 grades III vs. all 11 grades IIIIV). Six patients died (1 death in grades III vs. 5 in grades IIIIV). Ten patients had worsened symptoms at the last follow-up. The median progression-free survival in grade I, II, III, and IV tumors was 116, 36, 8, and 8.5 months, respectively. The median overall survival in grade I, II, III, and IV tumors was 142, 69, 19, and 12 months, respectively. Thrombotic complications occurred in 2 patients, one with isocitrate dehydrogenasewild type glioblastoma.

CONCLUSIONS

Outcomes worsen with higher grades and lead to difficult postoperative periods. Clinicians should be vigilant for thromboembolic complications. Further research is needed to understand these rare tumors.

Prognostic factors for surgically managed intramedullary spinal cord tumours: a single-centre case series

PURPOSE

Intramedullary spinal cord tumours (IMSCTs) are comparatively rare neoplasms. We present a single-centre clinical case series of adult patients with surgically managed IMSCTs.

METHODS

We performed a retrospective analysis of electronic patient records in the time period spanning July 2010 to July 2021. All adult patients that had undergone surgical management for IMSCTs were eligible for inclusion. Baseline and post-operative clinical and radiological characteristics, along with follow-up data, were assessed. We also performed a literature review with a focus on surgical outcomes for IMSCTs.

RESULTS

Sixty-six patients matched our selection criteria, with a median age of 42 years (range 23-85). Thirty-four ependymomas, 17 haemangioblastomas, 12 astrocytomas, 2 lymphomas and 1 teratoma were included. Statistical analysis yielded several significant findings: IMSCTs spanning a greater number of vertebral levels are significantly associated with poor McCormick outcomes (p = 0.03), presence of gait disturbance before surgery is significantly associated with poor outcome for both post-operative McCormick and Nurick scores (p = 0.007), and radicular pain present pre-operatively is significantly associated with a good post-operative McCormick score (p = 0.045). Haemangioblastomas are significantly more likely to have a clear intra-operative dissection plane compared to ependymomas and astrocytomas (p = 0.009). However, astrocytomas have a significantly higher prevalence of good McCormick outcomes compared to ependymomas and haemangioblastomas (p = 0.03).

CONCLUSION

Histological diagnosis, cranio-caudal extent of the tumour and the presence or absence of baseline deficits-such as gait impairment and radicular pain-are significant in determining neurological outcomes after surgery for IMSCTs.

Comparing Two Improved Techniques With the Traditional Surgical Techniques for Intra and Extramedullary Spinal Tumor Resection: A Report of 280 Cases

Objectives

Spinal tumors remain a challenging problem in modern neurosurgery. The high rate of postoperative morbidity associated with intramedullary tumors makes the need for safer surgical techniques invaluable. This study analyses our experience with the treatment of spinal cord tumors and compares traditional management and a new different surgical approach to intramedullary tumors with an associated hydrosyringomyelia.

Materials and Methods

This retrospective study compared standard surgical techniques and 2 newer modified techniques for intra and extramedullary spinal tumors at the Neurosurgery center for spinal cord tumors of the Republic of Uzbekistan. Preoperative neurological status was recorded with the ASIA/ISNCSCI scale. Postoperative outcome was graded using the Nurrick score.

Results

Of the 280 cases, there were 220 (78.5%) extramedullary and 60 (21.5%) with intramedullary spinal tumors. The control and main group had 159 (56.8%) and 121 (43.2%) patients, respectively. Severe compression myelopathy (ASIA- A, B, C) was 217 (77.5%) patients i.e., ASIA A-39 (13.9%); B-74 (26.4%), and C-104 (37.1%). In 74 extramedullary tumors (33.6%) treated with the new method, good postoperative outcomes in 44 cases (59.5%) with OR = 1.9; 95% CI 1.1–3.3 (p < 0.05). Thirty-seven (61.7%) intramedullary tumors were treated with the newer modified technique. There was no difference with the standard method (p = 0.15). However, when comparing postoperative Nurick grade 1–2 with grade 3–4, the newer strategy was superior with improvement in 24 (65%) patients, OR = 3.46; 95% CI 1.2–10.3 (p < 0.05).

Conclusion

When compared with standard methods, the proposed newer modified strategy of surgical treatment of spinal cord tumors with the insertion of a syringosubarachnoid shunt in the presence of an associated hydrosyringomyelia is associated with better postoperative outcome (Nurick 1 and 2) in 64.8%.

Intramedullary spinal cord and filum tumours-long-term outcome: single institution case series

BACKGROUND

Intramedullary spinal cord tumours are rare and account for about 2-4% of primary CNS tumours. Ependymomas and astrocytomas are most frequent. The aim of this study was to evaluate the long-term neurological outcome, quality of life (QoL), survival, need for additional treatment and frequency of neuropathic pain in a patient group treated at a tertiary university hospital.

METHOD

Retrospective descriptive study of 52 long-term survivors with intramedullary or filum tumours consenting to participate in this study. Fifty-six operations were performed in 48 patients. Clinical and radiological follow-up period was 113 and 117 months, respectively.

RESULTS

Good neurological outcome (ASIA score D or E, modified McCormick grade 1 or 2) was achieved in 88%. We found two negative prognostic factors in regards of severe disability which were large craniocaudal tumour size (p = 0.004) and histologic verified astrocytomas (p = 0.002). SF-36 results showed significantly lower results on all five subdomains concerning physical function, whereas scores for mental health and role emotional showed no significant differences compared to Norwegian norms. Ten patients including all astrocytoma patients, one primitive neuroectodermal tumour and three recurrent tumours of filum terminale had adjuvant therapy. None of the patients with intramedullary ependymoma had adjuvant therapy. Neuropathic pain was present in 54% of patients at the last follow-up.

CONCLUSION

This series shows that good results can be obtained with surgery for intramedullary tumours, even without perioperative neurophysiological monitoring. Multicentre studies are needed for further evaluation of negative and positive prognostic factors to further improve outcome.

Spinal hemangioblastomas: analysis of surgical outcome and prognostic factors

The prognostic factors for surgically removed spinal hemangioblastomas, the impact of VHL disease on outcome, and the role of intraoperative neuromonitoring are still not completely clear. The aim of this study was to review our experience with spinal hemangioblastomas in order to assess potential predictors of neurological outcome after surgery. All cases of spinal hemangioblastomas removed at two Italian academic institutions from 1985 to 2020 were reviewed. Data about clinical presentation and symptom duration, diagnosis of VHL, surgical approach, use of IONM, duration of hospital stay, follow-up, and modified McCormick grade before and after surgery were extracted. Sixty-one patients (31 F, 30 M) underwent 69 surgeries to remove 74 spinal hemangioblastomas (37 cervical, 32 thoracic, 5 lumbar). Improvement was found in 32.3% of cases, neurological condition remained stable in 51.6% of cases, and deteriorated in 16.1% of patients. A worsening trend in VHL patients and an improvement trend in non-VHL patients were detected, despite the lack of statistical significance. Laminotomy and use of IONM were found to be associated with better outcome, although no association was found between surgery without IONM and worse outcome. In most cases, patients affected by spinal hemangioblastomas can expect a good long-term outcome. In our experience, laminotomy seems to be associated with better outcome compared to laminectomy. While its absence is not associated with worse outcome, IONM seems to be associated with a better neurological outcome. Our study suggests that the more impaired the preoperative neurological condition, the worse the outcome.

Surgical outcome and prognostic factors in spinal cord ependymoma: a single-center, long-term follow-up study

Objective:

Spinal cord ependymomas account for 3–6% of all central nervous system tumors and around 60% of all intramedullary tumors. The aim of this study was to analyze the neurological outcome after surgery and to determine prognostic factors for functional outcome.

Patients and Methods:

Patients treated surgically due to a spinal cord ependymoma between 1990 and 2018 were retrospectively included. Demographics, neurological symptoms, radiological parameters, histopathology, and neurological outcome (using McCormick Score [MCS]) were analyzed. Possible prognostic factors for neurological outcome were evaluated.

Results:

In total, 148 patients were included (76 males, 51.4%). The mean age was 46.7 ± 15.3 years. The median follow-up period was 6.8 ± 5.4 years. The prevalence was mostly in the lumbar spine (45.9%), followed by the thoracic spine (28.4%) and cervical spine (25.7%). Gross-total resection was achieved in 129 patients (87.2%). The recurrence rate was 8.1% and depended on the extent of tumor resection (p = 0.001). Postoperative temporary neurological deterioration was observed in 63.2% of patients with ependymomas of the cervical spine, 50.0% of patients with ependymomas of the thoracic spine, and 7.4% of patients with ependymomas of the lumbosacral region. MCS 1–2 was detected in nearly two-thirds of patients with cervical and thoracic spinal cord ependymoma 36 months after surgery. Neurological recovery was superior in thoracic spine ependymomas compared with cervical spine ependymomas. Poor preoperative functional condition (MCS >2), cervical and thoracic spine location, and tumor extension >2 vertebrae were independent predictors of poor neurological outcome.

Conclusion:

Neurological deterioration was seen in the majority of cervical and thoracic spine ependymomas. Postoperative improvement was less in thoracic cervical spine ependymomas compared with thoracic spine ependymomas. Poor preoperative status and especially tumor extension >2 vertebrae are predictors of poor neurological outcome (MCS >2).

High frequency of disease progression in pediatric spinal cord low-grade glioma (LGG): management strategies and results from the German LGG study group

BACKGROUND

Knowledge on management of pediatric spinal cord low-grade glioma (LGG) is scarce.

METHODS

We analyzed clinical datasets of 128 pediatric patients with spinal LGG followed within the prospective multicenter trials HIT-LGG 1996 (n = 36), SIOP-LGG 2004 (n = 56), and the subsequent LGG-Interim registry (n = 36).

RESULTS

Spinal LGG, predominantly pilocytic astrocytomas (76%), harbored KIAA1549-BRAF fusion in 14/35 patients (40%) and FGFR1-TACC1 fusion in 3/26 patients (12%), as well as BRAFV600E mutation in 2/66 patients (3%). 10-year overall survival (OS) and event-free survival (EFS) was 93% ± 2% and 38% ± 5%, respectively. Disseminated disease (n = 16) was associated with inferior OS and EFS, while age ≥11 years and total resection were favorable factors for EFS. We observed 117 patients following total (n = 24) or subtotal/partial resection (n = 74), biopsy (n = 16), or radiologic diagnosis only (n = 3). Eleven patients were treated first with chemotherapy (n = 9) or irradiation (n = 2). Up to 20.8 years after diagnosis/initial intervention, 73/128 patients experienced one (n = 43) or up to six (n = 30) radiological/clinical disease progressions. Tumor resections were repeated in 36 patients (range, 2-6) and 47 patients required nonsurgical treatment (chemotherapy, n = 20; radiotherapy, n = 10; multiple treatment lines, n = 17). Long-term disease control for a median of 6.5 (range, 0.02-20) years was achieved in 73/77 patients following one (n = 57) or repeated (n = 16) resections, and in 35/47 patients after nonsurgical treatment.

CONCLUSIONS

The majority of patients experienced disease progression, even after years. Multiple interventions were required for more than a third, yet multimodal treatment enabled long-term disease control. Molecular testing may reveal therapeutic targets.

Surgical treatment and outcomes of intramedullary tumors by minimally invasive approach: Answer

The surgical outcomes which evaluated in studies depend on preoperative condition, demographic data of patients, surgical approaches or treatment and local factors. Author argues that the neurological deterioration rate 4,2% which is reported in our study is marvelous and he exemplifies the other studies in literature. Neurosurgeons know that the clinical studies in literature do not compare only their results. Authors compare and evaluate studies with preoperative demographic data, surgical approach, local factors or others between their results. Therefore this detail explains paralogism of the author. The neurological deterioration rate is reported as smaller or similar in our study to the contrary of others due to all the preoperative demographical data were evaluated with others. We suppose the author alludes that the neurological deterioration rate is marvelous since he does not compare all of the demographical data in these clinical studies.

Refining the treatment of spinal cord lesions: experience from 500 cases

OBJECTIVE

Tumorous lesions of the spinal cord, as well as some vascular lesions like cavernous hemangiomas, demand careful consideration as to the indication and approach for surgery. As these lesions are rare in any departmental series, refinement of treatment strategies evolves over long periods. In this context, the authors evaluated a series of 500 intramedullary lesions for approach, technique, outcome, complications, and follow-up.

METHODS

Five hundred intramedullary lesions in 460 patients were treated with a continuously evolving departmental strategy between 1985 and 2020. No lesions of the cauda equina or filum terminale were included. The focus of the evaluation was on the adaptation of exposure, resective methodology, sequelae, imaging, and rate of recurrence. Thirty-seven patients were children at the time of diagnosis.

RESULTS

Among the 348 neoplastic lesions, the largest subtype was ependymoma (n = 192, 55.2%), followed by astrocytoma (n = 89, 25.6%). As a trend, metastases (n = 21) have become more frequent and more apparent only in the past 15 years. Reoperations for recurrent or progressive cases or referrals after incomplete resection were performed in 56 cases, mostly for progressive diffuse or pilocytic astrocytomas. Among the vascular lesions, 68 (54.8%) were hemangioblastomas, followed by 56 (45.2%) cavernous hemangiomas. All intramedullary tumors were approached through a midline myelotomy, refining an en bloc resection technique for endophytic tumors to increase the rate of radical resection. Cavernous hemangiomas reaching the surface and hemangioblastomas were approached directly. Complete removal was possible in 77.2% of endophytic tumors but in only 41.7% of diffuse tumors. All WHO grade II diffuse astrocytomas, WHO grade III tumors, and glioblastoma progressed despite treatment according to standard regimens. Vascular lesions were regularly removed completely, with only 1 recurrence of a large hemorrhagic thoracic cavernous hemangioma. The major sequelae were sensory deficits and neuropathic pain. Stabilizing instrumentation was placed in 5 cases of spinal deformity, mostly when more than 4 levels were affected, and in the pediatric population.

CONCLUSIONS

In a large series of intramedullary surgeries, refinement of treatment strategies related to exposure, implementation of intraoperative adjuncts such as ultrasound, intraoperative neuromonitoring, resective strategies, and reconstruction were evaluated. The authors found that for almost any defined, endophytic medullary lesion, a safe and complete removal can be offered.

5-ALA fluorescence for intraoperative visualization of spinal ependymal tumors and identification of unexpected residual tumor tissue: experience in 31 patients

OBJECTIVE

Gross-total resection (GTR) is the treatment of choice in the majority of patients suffering from spinal ependymal tumors. In such tumors, the extent of resection (EOR) is considered the key factor for tumor recurrence and thus patient prognosis. However, incomplete resection is not uncommon and leads to increased risk of tumor recurrence. One important cause of incomplete resection is insufficient intraoperative visualization of tumor tissue as well as residual tumor tissue. Therefore, the authors investigated the value of 5-aminolevulinic acid (5-ALA)-induced fluorescence in a series of spinal ependymal tumors for improved tumor visualization.

METHODS

Adult patients who underwent preoperative 5-ALA administration and surgery for a spinal ependymal tumor were included in this study. For each tumor, a conventional white-light microsurgical resection was performed. Additionally, the fluorescence status (strong, vague, or no fluorescence) and fluorescence homogeneity (homogenous or inhomogeneous) of the spinal ependymal tumors were evaluated during surgery using a modified neurosurgical microscope. In intramedullary tumor cases with assumed GTR, the resection cavity was investigated for potential residual fluorescing foci under white-light microscopy. In cases with residual fluorescing foci, these areas were safely resected and the corresponding samples were histopathologically screened for the presence of tumor tissue.

RESULTS

In total, 31 spinal ependymal tumors, including 27 intramedullary tumors and 4 intradural extramedullary tumors, were included in this study. Visible fluorescence was observed in the majority of spinal ependymal tumors (n = 25, 81%). Of those, strong fluorescence was noted in 23 of these cases (92%), whereas vague fluorescence was present in 2 cases (8%). In contrast, no fluorescence was observed in the remaining 6 tumors (19%). Most ependymal tumors demonstrated an inhomogeneous fluorescence effect (17 of 25 cases, 68%). After assumed GTR in intramedullary tumors (n = 15), unexpected residual fluorescing foci within the resection cavity could be detected in 5 tumors (33%). These residual fluorescing foci histopathologically corresponded to residual tumor tissue in all cases.

CONCLUSIONS

This study indicates that 5-ALA fluorescence makes it possible to visualize the majority of spinal ependymal tumors during surgery. Unexpected residual tumor tissue could be detected with the assistance of 5-ALA fluorescence in approximately one-third of analyzed intramedullary tumors. Thus, 5-ALA fluorescence might be useful to increase the EOR, particularly in intramedullary ependymal tumors, in order to reduce the risk of tumor recurrence.

Long-term outcomes of spinal ependymomas: an institutional experience of more than 60 cases

PURPOSE

Spinal ependymomas represent the most common primary intramedullary tumors for which optimal management remains undefined. When possible, gross total resection (GTR) is often the mainstay of treatment, with consideration of radiotherapy (RT) in cases of residual or recurrent tumor. The impact of extent of resection and radiotherapy remain understudied.

OBJECTIVE

Report on a large institutional cohort with lengthy follow-up to provide information on long-term outcomes and to contribute to limited data assessing the value of extent of resection and RT.

METHODS

Patients with pathologically proven primary spinal ependymoma between 1990 and 2018 were identified. Kaplan-Meier estimates were used to calculate progression-free survival (PFS); local-control (LC) and overall survival (OS). Logistic regression was used to analyze variables' association with receipt of RT.

RESULTS

We identified 69 patients with ependymoma of which 4 had leptomeningeal dissemination at diagnosis and were excluded. Of the remaining cohort (n = 65), 42 patients (65%) had Grade II spinal ependymoma, 20 (31%) had Grade I myxopapillary ependymoma and 3 (5%) had Grade III anaplastic ependymoma; 54% underwent GTR and 39% underwent RT. With a median follow-up of 5.7 years, GTR was associated with improved PFS. For grade II lesions, STR+RT yielded better outcomes than STR alone (10y PFS 77.1% vs 68.2%, LC 85.7% vs 50%). Degree of resection was the only significant predictor of adjuvant radiotherapy (p < 0.0001).

CONCLUSION

Our findings confirm the importance of GTR in spinal ependymomas. Adjuvant RT should be utilized in the setting of a subtotal resection with expectation of improved disease-related outcomes.

Individualized Prediction of Overall Survival for Primary Intramedullary Spinal Cord Grade II/III Ependymoma

BACKGROUND

The purpose of this study was to develop and validate a nomogram to predict overall survival (OS) for adult patients with primary intramedullary spinal cord grade II/III ependymoma (PISCGE). We also elucidated the effectiveness of postoperative radiotherapy for this disease.

METHODS

Clinical data of patients with PISCGE between 1988 and 2015 were collected from the Surveillance, Epidemiology, and End Results (SEER) registry database. The independent prognostic factors were identified using univariate and multivariate Cox analyses. The nomogram was established from the results of the multivariate Cox analysis. We also use some methods to verify the superiority of the prediction model. The effectiveness of postoperative radiotherapy for PISCGE was assessed through coarsened exact matching and survival analyses.

RESULTS

Multivariate Cox analysis revealed that sex, age, surgical treatment, tumor grade, and marital status were independent prognostic factors of OS. The nomogram model was established based on these factors and validated internally. Calibration plots based on bootstrap resampling validation showed good consistency between the nomogram prediction and actual observation. This model also exhibited favorable discrimination characteristics. A risk classification system based on a nomogram was established to promote risk stratification of PISCGE and optimize clinical management. Moreover, we found no association between radiation treatment and the OS for these patients (P > 0.05).

CONCLUSIONS

We built the first nomogram model and risk classification system for PISCGE patients. Our model accurately estimated the individual OS probability of these patients, and proposes different treatment approaches for patients based on the risk classification system. Furthermore, from our findings, radiotherapy confers no survival advantage to these patients.

Intramedullary spinal cord tumours - a single Centre, 10-year review of clinical and pathological outcomes

BACKGROUND

Intramedullary spinal cord tumours are relatively rare tumours of the central nervous system. Surgical outcomes are affected by many variables, including pre-operative neurological function, tumour histology and extent of resection. Emphasis remains on surgical treatment due to limited adjunctive therapeutic options and poor drug penetration.

OBJECTIVE

To identify clinically relevant predictors of progression free survival by retrospectively analysing the extent of resection, pre- and post-operative neurological function and histology in intramedullary spinal cord tumours from a single neurosurgical centre over 10 years.

METHODS

Forty-three adult cases were identified from a surgical database. Variables collected included pre-and post-operative Frankel Grade and Modified McCormick Scale assessments, tumour histology, extent of resection and length of follow up. Chi-Squared, Kaplan-Mier Survival and Mann-Whitney U-tests were completed.

RESULTS

Ependymoma (41.9%) and haemangioblastoma (14.0%) were the commonest tumour histologies. In total, 17 different histological tumours were identified in the series. There was a statistically significant relationship between identification of the tumour plane and extent of resection (p < 0.01), along with the extent of resection and recurrence (p = 0.04). Compared to the other histological subtypes, ependymoma's demonstrated a significantly greater extent of resection (p = 0.01). There was a significant relationship between the grade of tumour and progression-free survival (p < 0.01).

CONCLUSION

Tumour plane and the extent of tumour resection are significant determinants of progression-free survival. Ependymoma, whilst being the commonest histology in our series were also the most resectable. Whilst complete resection reduces the rate of recurrence, tumour grade is the most important predictor of outcome. Given the importance of the extent of resection, and following a similar trend to other low volume pathologies, these tumours should only be tackled by neurosurgeons with experience in their resection.

Reduced field of view echo-planar imaging diffusion tensor MRI for pediatric spinal tumors

OBJECTIVE

Spine MRI is a diagnostic modality for evaluating pediatric CNS tumors. Applying diffusion-weighted MRI (DWI) or diffusion tensor imaging (DTI) to the spine poses challenges due to intrinsic spinal anatomy that exacerbates various image-related artifacts, such as signal dropouts or pileups, geometrical distortions, and incomplete fat suppression. The zonal oblique multislice (ZOOM)-echo-planar imaging (EPI) technique reduces geometric distortion and image blurring by reducing the field of view (FOV) without signal aliasing into the FOV. The authors hypothesized that the ZOOM-EPI method for spine DTI in concert with conventional spinal MRI is an efficient method for augmenting the evaluation of pediatric spinal tumors.

METHODS

Thirty-eight consecutive patients (mean age 8 years) who underwent ZOOM-EPI spine DTI for CNS tumor workup were retrospectively identified. Patients underwent conventional spine MRI and ZOOM-EPI DTI spine MRI. Two blinded radiologists independently reviewed two sets of randomized images: conventional spine MRI without ZOOM-EPI DTI, and conventional spine MRI with ZOOM-EPI DTI. For both image sets, the reviewers scored the findings based on lesion conspicuity and diagnostic confidence using a 5-point Likert scale. The reviewers also recorded presence of tumors. Quantitative apparent diffusion coefficient (ADC) measurements of various spinal tumors were extracted. Tractography was performed in a subset of patients undergoing presurgical evaluation.

RESULTS

Sixteen patients demonstrated spinal tumor lesions. The readers were in moderate agreement (kappa = 0.61, 95% CI 0.30-0.91). The mean scores for conventional MRI and combined conventional MRI and DTI were as follows, respectively: 3.0 and 4.0 for lesion conspicuity (p = 0.0039), and 2.8 and 3.9 for diagnostic confidence (p < 0.001). ZOOM-EPI DTI identified new lesions in 3 patients. In 3 patients, tractography used for neurosurgical planning showed characteristic fiber tract projections. The mean weighted ADCs of low- and high-grade tumors were 1201 × 10-6 and 865 × 10-6 mm2/sec (p = 0.002), respectively; the mean minimum weighted ADCs were 823 × 10-6 and 474 × 10-6 mm2/sec (p = 0.0003), respectively.

CONCLUSIONS

Diffusion MRI with ZOOM-EPI can improve the detection of spinal lesions while providing quantitative diffusion information that helps distinguish low- from high-grade tumors. By adding a 2-minute DTI scan, quantitative diffusion information and tract profiles can reliably be obtained and serve as a useful adjunct to presurgical planning for pediatric spinal tumors.

Surgical Treatment of Intra- and Juxtamedullary Spinal Cord Tumors: A Population Based Observational Cohort Study

Objective: Intramedullary spinal cord tumors (IMSCT) are rare entities and high-level evidence regarding optimal treatment is lacking. We aim to describe the demographics, histopathological distribution, onset symptoms, treatment strategies, and functional outcome for patients surgically treated for IMSCT.

Methods: We performed a retrospective review of a consecutive population-based cohort of 95 patients who underwent surgery for intra- or juxtamedullary tumors at a single institution during the period 2004–2017.

Results: When gross total resection (GTR) was achieved, we found no case of local tumor recurrence even in the absence of adjuvant radio- or chemotherapy. Meanwhile, we found a 50% progression rate on long-term MRI follow-up in patients where only a partial resection was possible. At long-term follow-up, there was no significant alteration in functional status, while a significant reduction in share of patients reporting pain, compared to preoperative status, was identified. Poor preoperative functional status and postoperative tumor remnant were identified as individual risk factors for further functional decline.

Conclusion: Gross total resection, with minimal post-operative neurological deterioration, is possible in the majority of the cases, especially in the presence of an identifiable resection plane between tumor and healthy spinal cord. Since long-term progression-free survival could be achieved by GTR without additional adjuvant treatment, we emphasize that low-grade tumors should not be subject to radiotherapy. Treatment of high-grade or diffusely infiltrating tumors, tumor remnants, or metastases should be individualized.

Remission after complete excision of an intramedullary hemangioma with an identifiable tumor plane in a dog

OBJECTIVE

To describe the use of an identifiable tumor plane (ITP) during myelotomy to excise an intramedullary hemangioma in a dog and report the outcome.

STUDY DESIGN

Case report.

ANIMALS

One 5.5-year-old 42.9-kg spayed female Leonberger dog.

METHODS

Clinical signs included progressive proprioceptive deficits of both pelvic limbs. Magnetic resonance imaging was consistent with a dorsal intramedullary mass at L3-L4. A laminectomy of the third and fourth lumbar vertebrae provided access for dorsal myelotomy. A clear surgical ITP was identified between the intramedullary mass and the spinal cord facilitating complete surgical resection.

RESULTS

Histopathological examination was consistent with a hemangioma. Postoperative MRI was consistent with complete excision of the mass. No evidence of recurrence was found by MRI at 3 months and at 22 months after surgery. Mild proprioceptive deficits persisted in the right pelvic limb.

CONCLUSION

A clear ITP was present, and gross-total resection (GTR) was achieved without significant morbidity. Persistent clinical remission resulted from surgery as the sole therapy.

CLINICAL SIGNIFICANCE

For an intramedullary tumor, GTR is the absence of visible tumor on intraoperative inspection combined with the absence of intramedullary contrast enhancement on postoperative MRI. When an ITP is present, GTR and resultant long-term remission may be more likely.

Diagnostic and therapeutic values of intraoperative electrophysiological neuromonitoring during resection of intradural extramedullary spinal tumors: a single-center retrospective cohort and meta-analysis

OBJECTIVE

With the advent of intraoperative electrophysiological neuromonitoring (IONM), surgical outcomes of various neurosurgical pathologies, such as brain tumors and spinal deformities, have improved. However, its diagnostic and therapeutic value in resecting intradural extramedullary (ID-EM) spinal tumors has not been well documented in the literature. The objective of this study was to summarize the clinical results of IONM in patients with ID-EM spinal tumors.

METHODS

A retrospective patient database review identified 103 patients with ID-EM spinal tumors who underwent tumor resection with IONM (motor evoked potentials, somatosensory evoked potentials, and free-running electromyography) from January 2010 to December 2015. Patients were classified as those without any new neurological deficits at the 6-month follow-up (group A; n = 86) and those with new deficits (group B; n = 17). Baseline characteristics, clinical outcomes, and IONM findings were collected and statistically analyzed. In addition, a meta-analysis in compliance with the PRISMA guidelines was performed to estimate the overall pooled diagnostic accuracy of IONM in ID-EM spinal tumor resection.

RESULTS

No intergroup differences were discovered between the groups regarding baseline characteristics and operative data. In multivariate analysis, significant IONM changes (p < 0.001) and tumor location (thoracic vs others, p = 0.018) were associated with new neurological deficits at the 6-month follow-up. In predicting these changes, IONM yielded a sensitivity of 82.4% (14/17), specificity of 90.7% (78/86), positive predictive value (PPV) of 63.6% (14/22), negative predictive value (NPV) of 96.3% (78/81), and area under the curve (AUC) of 0.893. The diagnostic value slightly decreased in patients with schwannomas (AUC = 0.875) and thoracic tumors (AUC = 0.842). Among 81 patients who did not demonstrate significant IONM changes at the end of surgery, 19 patients (23.5%) exhibited temporary intraoperative exacerbation of IONM signals, which were recovered by interruption of surgical maneuvers; none of these patients developed new neurological deficits postoperatively. Including the present study, 5 articles encompassing 323 patients were eligible for this meta-analysis, and the overall pooled diagnostic value of IONM was a sensitivity of 77.9%, a specificity of 91.1%, PPV of 56.7%, and NPV of 95.7%.

CONCLUSIONS

IONM for the resection of ID-EM spinal tumors is a reasonable modality to predict new postoperative neurological deficits at the 6-month follow-up. Future prospective studies are warranted to further elucidate its diagnostic and therapeutic utility.

Spinal Myxopapillary Ependymoma: The Sapienza University Experience and Comprehensive Literature Review Concerning the Clinical Course of 1602 Patients

BACKGROUND

Spinal myxopapillary ependymoma (sMPE) is an uncommon primary spinal neoplasm infiltrating the spinal cord, conus medullaris (CM), and nerve roots. It is associated with low resection and high recurrence rates. The purpose of this literature review is to evaluate the exact impact of the involvement of the CM and the role played by gross total resection (GTR) on overall survival (OS).

METHODS

The English literature was systematically investigated using MEDLINE, the NIH Library, PubMed, and Google Scholar search engines with relevant queries. Case series reporting details concerning OS, GTR, and CM involvement rate were included, with a differential statistical weight given by the number of patients enrolled. A final cohort of 1602 clinical records was analyzed according to the 3 selected end point variables.

RESULTS

The average age was 36.44 ± 3.41 years, and the CM was involved in 28.4% ± 28.2% of cases. The average GTR rate was 53.94% ± 22.20%. Five- and 10-year OS rates were respectively available in 1170 and 1167 cases, with an average 5- and 10-year OS rate of 94.99% ± 3.87% and 92.31% ± 5.73%. By means of analyses performed both on aggregated and disaggregated data a strong positive statistical connection between GTR and increased OS was demonstrated despite the real clinical advantage could range as low as around 1% of increased OS rate.

CONCLUSIONS

Given the indolent sMPE behavior, it is difficult to evaluate the exact impact of GTR and CM involvement on OS; however, GTR could be associated with a limited survival advantage, whereas CM involvement could be associated with a survival disadvantage.

Retrospective Study on Accuracy of Intraoperative Frozen Section Biopsy in Spinal Tumors

OBJECTIVE

Histologic types and grades are critical in the diagnosis and treatment of spinal tumors. Intraoperative frozen section is a fast and easy method in confirming pathologic diagnosis during the operation. This study was undertaken to reveal the accuracy of intraoperative frozen section biopsy in order to make proper treatment plans.

METHODS

This retrospective study concerned patients who underwent spinal tumor surgeries from 1 January, 2012 to 31 December, 2016. Frozen section biopsy and permanent biopsy were compared, and cases that had differences were counted.

RESULTS

Thirty-seven cases out of 324 patients had discrepancies (11.4%). In discrepant cases 11 cases were ependymoma (29.7%) and 6 cases were schwannoma (16.2%). Among 34 patients who were finally diagnosed with an ependymoma, 11 cases had discrepancies, which was the highest mismatch rate among tumor final pathologic types. By frozen biopsy, astrocytoma (n = 5) and ependymoma (n = 5) turned out to be the most discrepant pathologic types and 16 frozen section biopsy cases were "null." Frozen biopsy astrocytoma (n = 5) mostly turned out to be ependymoma in 4 cases.

CONCLUSIONS

Pathologic findings from frozen biopsy for spinal cord tumors could not be corresponded to final diagnosis, especially when the results of frozen biopsy were ependymoma or astrocytoma. Therefore careful decision making for treatment plans is required.

Magnetic Drug Targeting: A Novel Treatment for Intramedullary Spinal Cord Tumors

Most applications of nanotechnology in cancer have focused on systemic delivery of cytotoxic drugs. Systemic delivery relies on accumulation of nanoparticles in a target tissue through enhanced permeability of leaky vasculature and retention effect of poor lymphatic drainage to increase the therapeutic index. Systemic delivery is limited, however, by toxicity and difficulty crossing natural obstructions, like the blood spine barrier. Magnetic drug targeting (MDT) is a new technique to reach tumors of the central nervous system. Here, we describe a novel therapeutic approach for high-grade intramedullary spinal cord tumors using magnetic nanoparticles (MNP). Using biocompatible compounds to form a superparamagnetic carrier and magnetism as a physical stimulus, MNP-conjugated with doxorubicin were successfully localized to a xenografted tumor in a rat model. This study demonstrates proof-of-concept that MDT may provide a novel technique for effective, concentrated delivery of chemotherapeutic agents to intramedullary spinal cord tumors without the toxicity of systemic administration.

Intradural spinal tumors in adults-update on management and outcome

Among spinal tumors that occur intradurally, meningiomas, nerve sheath tumors, ependymomas, and astrocytomas are the most common. While a spinal MRI is the state of the art to diagnose intradural spinal tumors, in some cases CT scans, angiography, CSF analyses, and neurophysiological examination can be valuable. The management of these lesions depends not only on the histopathological diagnosis but also on the clinical presentation and the anatomical location, allowing either radical resection as with most extramedullary lesions or less invasive strategies as with intramedullary lesions. Although intramedullary lesions are rare and sometimes difficult to manage, well-planned treatment can achieve excellent outcome without treatment-related deficits. Technical advances in imaging, neuromonitoring, minimally invasive approaches, and radiotherapy have improved the outcome of intradural spinal tumors. However, the outcome in malignant intramedullary tumors remains poor. While surgery is the mainstay treatment for many of these lesions, radiation and chemotherapy are of growing importance in recurrent and multilocular disease. We reviewed the literature on this topic to provide an overview of spinal cord tumors, treatment strategies, and outcomes. Typical cases of extra- and intramedullary tumors are presented to illustrate management options and outcomes.

Surgery for spinal intramedullary tumors: technique, outcome and factors affecting resectability

Intramedullary spinal cord tumors (IMSCTs) are relatively infrequent lesions with ependymomas and astrocytomas representing the most common types. Microsurgical resection is established as the treatment of choice for these challenging lesions. We reviewed the surgical outcome of 29 cases operated for IMSCTs by the same surgeon between 2009 and 2015. The median follow-up period was 31 months, and all patients were followed up at least for 1 year. Among these 29 cases, 5 patients were previously operated for partial resection elsewhere. Age ranged from 9 to 62 years with a median of 39 years. All patients were symptomatic before surgery. The most common pathology was ependymoma (16 cases), and the most common tumor location was the cervical spine (18 cases). Gross total resection was achieved in 20 out of 29 cases (68.9%). Tumors were totally excised in all cases of ependymoma except in two patients; one was previously operated and irradiated and the second had an extensive anaplastic ependymoma. Sixteen cases experienced immediate post-operative worsening which was temporary in all but one case. At 1-year follow up, 23 patients (79.3%) maintained their pre-operative McCormick grade, 5 patients (17.2%) had a better grade, and 1 patient (3.5%) deteriorated. Surgery still represents the mainstay in the management of IMSCT. Gross total resection can be achieved safely in many cases especially in the presence of an identifiable plane of cleavage between the tumor and the normal spinal cord.