Neurosurgery residency and fellowship education in the United States: 2 decades of system development by the One Neurosurgery Summit organizations.

The purpose of this report is to chronicle a 2-decade period of educational innovation and improvement, as well as governance reform, across the specialty of neurological surgery. Neurological surgery educational and professional governance systems have evolved substantially over the past 2 decades with the goal of improving training outcomes, patient safety, and the quality of US neurosurgical care. Innovations during this period have included the following: creating a consensus national curriculum; standardizing the length and structure of neurosurgical training; introducing educational outcomes milestones and required case minimums; establishing national skills, safety, and professionalism courses; systematically accrediting subspecialty fellowships; expanding professional development for educators; promoting training in research; and coordinating policy and strategy through the cooperation of national stakeholder organizations. A series of education summits held between 2007 and 2009 restructured some aspects of neurosurgical residency training. Since 2010, ongoing meetings of the One Neurosurgery Summit have provided strategic coordination for specialty definition, neurosurgical education, public policy, and governance. The Summit now includes leadership representatives from the Society of Neurological Surgeons, the American Association of Neurological Surgeons, the Congress of Neurological Surgeons, the American Board of Neurological Surgery, the Review Committee for Neurological Surgery of the Accreditation Council for Graduate Medical Education, the American Academy of Neurological Surgery, and the AANS/CNS Joint Washington Committee. Together, these organizations have increased the effectiveness and efficiency of the specialty of neurosurgery in advancing educational best practices, aligning policymaking, and coordinating strategic planning in order to meet the highest standards of professionalism and promote public health.

Perioperative Assessment of Cerebellar Masses and the Potential for Cerebellar Cognitive Affective Syndrome.

The cerebellum was long perceived to be a region of limited importance with primary functions in the regulation of motor control. A degree of its functional topography in motor modulation has been traditionally appreciated. However, an evolving body of evidence supports its role in a range of cognitive processes, including executive decision making, language, emotional processing, and working memory. To this end, numerous studies of cerebellar stroke syndromes as well as investigations with functional magnetic resonance imaging and diffusion tensor imaging have given clinicians a better model of the functional topography within the cerebellum and the essential lanes of communication with the cerebrum. With this deeper understanding, neurosurgeons should integrate these domains into the perioperative evaluation and postoperative rehabilitation of patients with cerebellar tumors. This review aims to discuss these understandings and identify valuable tools for implementation into clinical practice.

A novel, reproducible, and objective method for volumetric magnetic resonance imaging assessment of enhancing glioblastoma.

OBJECT: Robust methodology that allows objective, automated, and observer-independent measurements of brain tumor volume, especially after resection, is lacking. Thus, determination of tumor response and progression in neurooncology is unreliable. The objective of this study was to determine if a semi-automated volumetric method for quantifying enhancing tissue would perform with high reproducibility and low interobserver variability. METHODS: Fifty-seven MR images from 13 patients with glioblastoma were assessed using our method, by 2 neuroradiologists, 1 neurosurgeon, 1 neurosurgical resident, 1 nurse practitioner, and 1 medical student. The 2 neuroradiologists also performed traditional 1-dimensional (1D) and 2-dimensional (2D) measurements. Intraclass correlation coefficients (ICCs) assessed interobserver variability between measurements. Radiological response was determined using Response Evaluation Criteria In Solid Tumors (RECIST) guidelines and Macdonald criteria. Kappa statistics described interobserver variability of volumetric radiological response determinations. RESULTS: There was strong agreement for 1D (RECIST) and 2D (Macdonald) measurements between neuroradiologists (ICC = 0.42 and 0.61, respectively), but the agreement using the authors' novel automated approach was significantly stronger (ICC = 0.97). The volumetric method had the strongest agreement with regard to radiological response (κ = 0.96) when compared with 2D (κ = 0.54) or 1D (κ = 0.46) methods. Despite diverse levels of experience of the users of the volumetric method, measurements using the volumetric program remained remarkably consistent in all users (0.94). CONCLUSIONS: Interobserver variability using this new semi-automated method is less than the variability with traditional methods of tumor measurement. This new method is objective, quick, and highly reproducible among operators with varying levels of expertise. This approach should be further evaluated as a potential standard for response assessment based on contrast enhancement in brain tumors.

Morbidity, mortality, and health care costs for patients undergoing spine surgery following the ACGME resident duty-hour reform: Clinical article.

OBJECT: The Accreditation Council for Graduate Medical Education (ACGME) implemented resident duty-hour restrictions on July 1, 2003, in concern for patient and resident safety. Whereas studies have shown that duty-hour restrictions have increased resident quality of life, there have been mixed results with respect to patient outcomes. In this study, the authors have evaluated the effect of duty-hour restrictions on morbidity, mortality, length of stay (LOS), and charges in patients who underwent spine surgery. METHODS: The Nationwide Inpatient Sample was used to evaluate the effect of duty-hour restrictions on complications, mortality, LOS, and charges by comparing the prereform (2000-2002) and postreform (2005-2008) periods. Outcomes were compared between nonteaching and teaching hospitals using a difference-in-differences (DID) method. Results A total of 693,058 patients were included in the study. The overall complication rate was 8.6%, with patients in the postreform era having a significantly higher rate than those in the pre-duty-hour restriction era (8.7% vs. 8.4%, p < 0.0001). Examination of hospital teaching status revealed complication rates to decrease in nonteaching hospitals (8.2% vs. 7.6%, p < 0.0001) while increasing in teaching institutions (8.6% vs. 9.6%, p < 0.0001) in the duty-hour reform era. The DID analysis to compare the magnitude in change between teaching and nonteaching institutions revealed that teaching institutions to had a significantly greater increase in complications during the postreform era (p = 0.0002). The overall mortality rate was 0.37%, with no significant difference between the pre- and post-duty-hour eras (0.39% vs. 0.36%, p = 0.12). However, the mortality rate significantly decreased in nonteaching hospitals in the postreform era (0.30% vs. 0.23%, p = 0.0008), while remaining the same in teaching institutions (0.46% vs. 0.46%, p = 0.75). The DID analysis to compare the changes in mortality between groups revealed that the difference between the effects approached significance (p = 0.069). The mean LOS for all patients was 4.2 days, with hospital stay decreasing in nonteaching hospitals (3.7 vs. 3.5 days, p < 0.0001) while significantly increasing in teaching institutions (4.7 vs. 4.8 days, p < 0.0001). The DID analysis did not demonstrate the magnitude of change for each group to differ significantly (p = 0.26). Total patient charges were seen to rise significantly in the post-duty-hour reform era, increasing from $40,000 in the prereform era to $69,000 in the postreform era. The DID analysis did not reveal a significant difference between the changes in charges between teaching and nonteaching hospitals (p = 0.55). CONCLUSIONS: The implementation of duty-hour restrictions was associated with an increased risk of postoperative complications for patients undergoing spine surgery. Therefore, contrary to its intended purpose, duty-hour reform may have resulted in worse patient outcomes. Additional studies are needed to evaluate strategies to mitigate these effects and assist in the development of future health care policy.

Worse outcomes for patients undergoing brain tumor and cerebrovascular procedures following the ACGME resident duty-hour restrictions.

OBJECT: On July 1, 2003, the Accreditation Council for Graduate Medical Education (ACGME) implemented duty-hour restrictions for resident physicians due to concerns for patient and resident safety. Though duty-hour restrictions have increased resident quality of life, studies have shown mixed results with respect to patient outcomes. In this study, the authors have evaluated the effect of duty-hour restrictions on morbidity, mortality, length of stay, and charges in patients who underwent brain tumor and cerebrovascular procedures. METHODS: The Nationwide Inpatient Sample was used to evaluate the effect of duty-hour restrictions on complications, mortality, length of stay, and charges by comparing the pre-reform (2000-2002) and post-reform (2005-2008) periods. Outcomes were compared between nonteaching and teaching hospitals using a difference-in-differences (DID) method. RESULTS: A total of 90,648 patients were included in the analysis. The overall complication rate was 11.7%, with the rates not significantly differing between the pre- and post-duty hour eras (p = 0.26). Examination of hospital teaching status revealed that complication rates decreased in nonteaching hospitals (12.1% vs 10.4%, p = 0.0004) and remained stable in teaching institutions (11.8% vs 11.9%, p = 0.73) in the post-reform era. Multivariate analysis demonstrated a significantly higher complication risk in teaching institutions (OR 1.33 [95% CI 1.11-1.59], p = 0.0022), with no significant change in nonteaching hospitals (OR 1.11 [95% CI 0.91-1.37], p = 0.31). A DID analysis to compare the magnitude in change between teaching and nonteaching institutions revealed that teaching hospitals had a significantly greater increase in complications during the post-reform era than nonteaching hospitals (p = 0.040). The overall mortality rate was 3.0%, with a significant decrease occurring in the post-reform era in both nonteaching (5.0% vs 3.2%, p < 0.0001) and teaching (3.2% vs 2.3%, p < 0.0001) hospitals. DID analysis to compare the changes in mortality between groups did not reveal a significant difference (p = 0.40). The mean length of stay for all patients was 8.7 days, with hospital stay decreasing from 9.2 days to 8.3 days in the post-reform era (p < 0.0001). The DID analysis revealed a greater length of stay decrease in nonteaching hospitals than teaching institutions, which approached significance (p = 0.055). Patient charges significantly increased in the post-reform era for all patients, increasing from $70,900 to $96,100 (p < 0.0001). The DID analysis did not reveal a significant difference between the changes in charges between teaching and nonteaching hospitals (p = 0.17). CONCLUSIONS: The implementation of duty-hour restrictions correlated with an increased risk of postoperative complications for patients undergoing brain tumor and cerebrovascular neurosurgical procedures. Duty-hour reform may therefore be associated with worse patient outcomes, contrary to its intended purpose. Due to the critical condition of many neurosurgical patients, this patient population is most sensitive and likely to be negatively affected by proposed future increased restrictions.

Impact of PhD training on scholarship in a neurosurgical career.

OBJECT: The purpose of this study was to report the prevalence of neurosurgeons with both medical degrees (MDs) and doctorates (PhDs) at top-ranked US academic institutions and to assess whether the additional doctorate education is associated with substantive career involvement in academia as well as greater success in procuring National Institutes of Health (NIH) research funding compared with an MD-only degree. METHODS: The authors reviewed the training of neurosurgeons across the top 10 neurosurgery departments chosen according to academic impact (h index) to examine whether MD-PhD training correlated significantly with career outcomes in academia. RESULTS: Six hundred thirteen neurosurgery graduates and residents between the years 1990 and 2012 were identified for inclusion in this analysis. Both MD and PhD degrees were held by 121 neurosurgeons (19.7%), and an MD alone was held by 492. Over the past 2 decades, MD-PhD trainees represented a gradually increasing percentage of neurosurgeons, from 10.2% to 25.7% (p < 0.01). Of the neurosurgeons with MD-PhD training, a greater proportion had appointments in academic medicine compared with their MD-only peers (73.7% vs 52.3%, p < 0.001). Academic neurosurgeons with both degrees were also more likely to have received NIH funding (51.9% vs 31.8%, p < 0.05) than their single-degree counterparts in academia. In a national analysis of all active NIH R01 grants awarded in neurosurgery, MD-PhD investigators held a disproportionate number, more than 4-fold greater than their representation in the field. CONCLUSIONS: Dual MD-PhD training is a significant factor that may predict active participation in and funding for research careers among neurological surgeons at top-ranked academic institutions. These findings and their implications are of increasing relevance as the population of neurosurgeons with dual-degree training continues to rise.

Long-term economic impact of coiling vs clipping for unruptured intracranial aneurysms.

BACKGROUND: : Treatment of unruptured intracranial aneurysms (UIAs) involves endovascular coiling or aneurysm clipping. While many studies have compared these treatment modalities with respect to various clinical outcomes, few studies have investigated the economic costs associated with each procedure. OBJECTIVE: : To determine the reoperation rate, postoperative complications, and inpatient and outpatient costs associated with surgical or endovascular treatment of patients with UIAs in the United States. METHODS: : We utilized the MarketScan database to examine patients who underwent surgical clipping or endovascular coiling procedures for UIAs from 2000 to 2009, comparing reoperation rates, complications, and angiogram and healthcare resource use. Propensity score matching techniques were used to match patients. RESULTS: : We identified 4,504 patients with surgically treated UIAs, with propensity score matching of 3,436 patients. Reoperation rates were significantly lower in the clipping group compared to the coiling group at 1- (P < .001), 2- (P < .001), and 5 years (P < .001) following the procedure. However, postoperative complications (immediate, 30 and 90 days) were significantly higher in those undergoing surgical clipping. Although hospital length of stay and costs were higher in the clipping group for the index procedure, the number of postoperative angiograms and outpatient services used at 1, 2, and 5 years were significantly higher in the coiling group. CONCLUSION: : Though surgical clipping resulted in lower reoperation rates, it was associated with higher complication rates and initial costs. However, overall costs at 2 and 5 years were similar to endovascular coiling due to the significantly higher number of follow-up angiograms and outpatient costs in these patients. ABBREVIATIONS: : SAH, subarachnoid hemorrhageUIAs, unruptured intracranial aneurysms.

Vestibular schwannomas in the modern era: epidemiology, treatment trends, and disparities in management.

OBJECT: There are a variety of treatment options for the management of vestibular schwannomas (VSs), including microsurgical resection, radiotherapy, and observation. Although the choice of treatment is dependent on various patient factors, physician bias has been shown to significantly affect treatment choice for VS. In this study the authors describe the current epidemiology of VS and treatment trends in the US in the modern era. They also illustrate patient and tumor characteristics and elucidate their effect on tumor management. METHODS: Patients diagnosed with VS were identified through the Surveillance, Epidemiology, and End Results database, spanning the years 2004-2009. Age-adjusted incidence rates were calculated and adjusted using the 2000 US standard population. The chi-square and Student t-tests were used to evaluate differences between patient and tumor characteristics. Multivariate logistic regression was performed to determine the effects of various patient and tumor characteristics on the choice of tumor treatment. RESULTS: A total of 6225 patients with VSs treated between 2004 and 2009 were identified. The overall incidence rate was 1.2 per 100,000 population per year. The median age of patients with VS was 55 years, with the majority of patients being Caucasian (83.16%). Of all patients, 3053 (49.04%) received surgery only, with 1466 (23.55%) receiving radiotherapy alone. Both surgery and radiation were only used in 123 patients (1.98%), with 1504 patients not undergoing any treatment (24.16%). Increasing age correlated with decreased use of surgery (OR 0.95, 95% CI 0.95-0.96; p<0.0001), whereas increasing tumor size was associated with the increased use of surgery (OR 1.04, 95% CI 1.04-1.05; p<0.0001). Older age was associated with an increased likelihood of conservative management (OR 1.04, 95% CI 1.04-1.05; p<0.0001). Racial disparities were also seen, with African American patients being significantly less likely to receive surgical treatment compared with Caucasians (OR 0.50, 95% CI 0.35-0.70; p<0.0001), despite having larger tumors at diagnosis. CONCLUSIONS: The incidence of vestibular schwannomas in the US is 1.2 per 100,000 population per year. Although many studies have demonstrated improved outcomes with the use of radiotherapy for small- to medium-sized VSs, surgery is still the most commonly used treatment modality for these tumors. Racial disparities also exist in the treatment of VSs, with African American patients being half as likely to receive surgery and nearly twice as likely to have their VSs managed conservatively despite presenting with larger tumors. Further studies are needed to elucidate the reasons for treatment disparities and investigate the nationwide trend of resection for the treatment of small VSs.

A novel method for volumetric MRI response assessment of enhancing brain tumors.

Current radiographic response criteria for brain tumors have difficulty describing changes surrounding postoperative resection cavities. Volumetric techniques may offer improved assessment, however usually are time-consuming, subjective and require expert opinion and specialized magnetic resonance imaging (MRI) sequences. We describe the application of a novel volumetric software algorithm that is nearly fully automated and uses standard T1 pre- and post-contrast MRI sequences. T1-weighted pre- and post-contrast images are automatically fused and normalized. The tumor region of interest is grossly outlined by the user. An atlas of the nasal mucosa is automatically detected and used to normalize levels of enhancement. The volume of enhancing tumor is then automatically calculated. We tested the ability of our method to calculate enhancing tumor volume with resection cavity collapse and when the enhancing tumor is obscured by subacute blood in a resection cavity. To determine variability in results, we compared narrowly-defined tumor regions with tumor regions that include adjacent meningeal enhancement and also compared different contrast enhancement threshold levels used for the automatic calculation of enhancing tumor volume. Our method quantified enhancing tumor volume despite resection cavity collapse. It detected tumor volume increase in the midst of blood products that incorrectly caused decreased measurements by other techniques. Similar trends in volume changes across scans were seen with inclusion or exclusion of meningeal enhancement and despite different automated thresholds for tissue enhancement. Our approach appears to overcome many of the challenges with response assessment of enhancing brain tumors and warrants further examination and validation.

Critical assessment of operative approaches for hearing preservation in small acoustic neuroma surgery: retrosigmoid vs middle fossa approach.

BACKGROUND: For hearing preservation in acoustic neuroma (AN) surgery, the middle fossa (MF) or retrosigmoid (RS) approach can be used. Recent literature advocates the use of the MF approach, especially for small ANs. OBJECTIVE: To present our critical analysis of operative results comparing these 2 approaches. METHODS: We reviewed 504 consecutive AN resections performed between November 1998 and September 2007 and identified 43 MF and 82 RS approaches for tumors smaller than 1.5 cm during hearing preservation surgery. Individual cases were examined postoperatively with respect to hearing ability, facial nerve activity, operative time, blood loss, and symptoms resulting from retraction of the cerebellar or temporal lobes. RESULTS: Good hearing function (American Academy of Otolaryngology-Head and Neck Surgery class B or better) was preserved in 76.7% of patients undergoing surgery via the MF approach and in 73.2% of the RS group (P = .9024). Temporary facial nerve weakness was more frequent in the MF group (P = .0249). However, late (8-12 months) follow-up examinations showed good recovery in both groups. The mean operative time was 7.45 hours for the MF group and 5.2 hours for the RS group (P = .0318). The mean blood loss was 280.5 mL for the MF group and 80.8 mL for the RS group (P < .0001). Temporary symptoms of temporal lobe edema (drowsiness or speech disturbance) were noted in 6 MF cases. No cerebellar dysfunction was noted in the RS group. CONCLUSIONS: Although hearing and facial nerve function assessed at approximately 1 year was similar with these 2 approaches, the RS approach provided several advantages over the MF approach for ANs smaller than 1.5 cm.

Quantitative assessment of cardiorespiratory fitness, skeletal muscle function, and body composition in adults with primary malignant glioma.

BACKGROUND: The study was undertaken to evaluate cardiorespiratory fitness, skeletal muscle function, and body composition of patients with newly diagnosed and untreated, postsurgical primary malignant glioma. METHODS: By using a cross-sectional design, patients with clinically stable (10 +/- 7 days postsurgery) high-grade glioma (HGG; n = 25) or low-grade glioma (LGG; n = 10) were studied. Participants performed a cardiopulmonary exercise test (CPET) with expired gas analysis to assess cardiorespiratory fitness (peak oxygen consumption, VO2peak). Other physiological outcomes included skeletal muscle cross-sectional area (CSA; magnetic resonance imaging), isokinetic muscle strength (isokinetic dynamometer), and body composition (air displacement plethysmography). Quality of life was assessed with the Functional Assessment of Cancer Therapy-Brain scale. RESULTS: CPET was a feasible and safe procedure to assess VO2peak, with no serious adverse events. VO2peak indexed to total body weight and lean body mass (LBM) for both groups was 13.0 mL x weight x min(-1) and 19 mL x LBM x min(-1), the equivalent to 59% and 38% below age- and sex-predicted normative values, respectively. Skeletal muscle strength and mid-thigh CSA were lower in HGG relative to LGG patients (83 vs 125 Nm, P = .025; 94 vs 119 cm2, P = .171, respectively). Skeletal muscle isokinetic strength, CSA, and body composition outcomes predicted VO2peak (r = -0.59 to 0.68, P < .05). CONCLUSIONS: Postsurgical glioma patients have markedly reduced cardiorespiratory fitness, isokinetic strength, and CSA. Prospective studies are now required to determine whether such abnormalities influence treatment toxicity and clinical outcome as well as to test the effect of appropriately selected interventions to prevent and/or mitigate dysfunction.

Assessment of physical functioning in recurrent glioma: preliminary comparison of performance status to functional capacity testing.

BACKGROUND: Performance status (PS) scoring systems are tools of immense clinical importance in the management of patients with malignant disease but these tools are subjective and do not provide an objective evaluation of physical functioning. We conducted a pilot study to explore the feasibility and clinical utility of functional capacity testing to assess physical functioning in recurrent primary malignant glioma patients. PATIENTS AND METHODS: Using a cross-sectional design, consecutive patients with recurrent glioma performed a six minute walk (6MW) test to assess functional capacity. Performance status was assessed using Karnofsky Performance Status (KPS) scoring system. QOL was assessed by the Functional Assessment of Cancer Therapy-Brain scale. Self-reported exercise behavior was assessed using the Godin Leisure Time Exercise Questionnaire (GLTEQ). RESULTS: A total of 171 patients were recruited and tested. Seventy percent were diagnosed with glioblastoma multiforme (WHO grade IV) and 85% were undergoing therapy. Median KPS was 90% (range, 70-100%). Median 6MW distance was 400 m (range, 102-630 m), equivalent to 56 +/- 13% (range, 14-87%) of that predicted for age and sex. KPS, self-reported exercise, and QOL increased across 6MW distance quartiles (P < 0.05) although there was considerable variation within each category. 6MW distance and KPS were significantly correlated with each other (r = 0.34, P < 0.01) and several QOL domains (range, r = -0.43 to 0.46, P < 0.05). CONCLUSIONS: 6MW distance is a clinically feasible tool that provides an objective measure of physical functioning in select patients with recurrent glioma. Further research is required to investigate the prognostic value of these tests in patients with advanced malignancy.

Three-dimensional computed tomographic analysis of the relationship between the arcuate eminence and the superior semicircular canal.

OBJECTIVE: The location of the superior semicircular canal (SSC) is often determined intraoperatively based on its topographic association with the arcuate eminence (AE). This determination is not always possible because of the potential variability in the relationship between these two structures. The goal of this study was to describe the three-dimensional (3-D) relationship between the AE and SSC using 3-D computed tomography (CT) and to evaluate the utility of 3-D CT for preoperative planning for surgical approaches to the middle cranial fossa. METHODS: We studied 11 patients (22 sides) radiographically using 0.8- to 1-mm thick reconstructed CT images. A standard set of structural relationships was measured between the AE, SSC, and other regional landmarks. RESULTS: 3-D CT clearly demonstrated the relationships between traditional landmarks along the petrous ridge and middle cranial fossa. The relationship between the arcuate eminence and SSC was found to be highly variable. The average distance between the tips of the two structures was found to be 5.7 mm (range, 2.7-10.4 mm). CONCLUSIONS: There is significant variability in the relationship between the AE and the SSC. The AE is not a consistent or reliable landmark for identifying the precise position of the SSC. Detailed preoperative information regarding the relationship between the AE, SSC, and other bony landmarks can be easily and quickly assessed using 3-D CT.

Surgical management of petroclival meningiomas: defining resection goals based on risk of neurological morbidity and tumor recurrence rates in 137 patients.

OBJECTIVE: Meningiomas arising from the petroclival region remain a challenging surgical problem. Because of the substantial risk of neurological morbidity, uniformly pursuing a gross total resection (GTR) to minimize tumor recurrence rates may not be justified. We sought to define optimal resection goals based on risk factors for postoperative neurological morbidity and tumor recurrence rates. METHODS: This series represents our experience with 137 meningiomas arising from the petroclival region resected between June 1993 and October 2002. There were 38 male and 99 female patients with a mean age of 53 years. RESULTS: GTR was achieved in 40% of patients, and near total resection (NTR) was achieved in 40% of patients. One operative death occurred. Twenty-six percent of patients experienced new postoperative cranial nerve deficits, paresis, or ataxia when assessed at a mean follow-up of 8.3 months. The risk of cranial nerve deficits increased with prior resection (P < 0.001), preoperative cranial nerve deficit (P = 0.005), tumor adherence to neurovascular structures (P = 0.046), and fibrous tumor consistency (P = 0.005). The risk of paresis or ataxia increased with prior resection (P = 0.001) and tumor adherence (P = 0.045). Selective NTR rather than GTR in patients with adherent or fibrous tumors significantly reduced the rate of neurological deficits. Radiographic recurrence or progression occurred in 17.6% of patients at a mean follow-up of 29.8 months. Tumor recurrence rates after GTR and NTR did not differ significantly (P = 0.111). CONCLUSION: Intraoperatively defined tumor characteristics played a critical role in identifying the subset of patients with an increased risk of postoperative deficits. By selectively pursuing an NTR rather than a GTR, neurological morbidity was reduced significantly without significantly increasing the rate of tumor recurrence.