Faculty Bibliography

OBJECTIVE/BACKGROUND/OBJECTIVE:Meningiomas account for approximately one third of all brain tumors in the United States. In high-volume medical centers, the average length of stay (LOS) for a patient is 6.8 days compared with 8.8 days in low-volume centers with median total admission charges equaling approximately $55,000. To our knowledge, few studies have evaluated day of surgery and its effect on hospital LOS. Our primary goal was to analyze patient outcome as a direct result of surgical date, as well as to characterize the individual variables that may impact their hospital course, early access to rehabilitation, and long-term functional status. METHODS:A retrospective database was generated for cranial meningioma patients who underwent elective surgical resection at our institution over a 3-year study period (2011-2014). Inclusion criteria included any patient who underwent elective meningioma resection and was discharged either home or to a rehabilitation facility with at least 6 months of follow-up. Exclusion criteria included any patient who was not discharged after resection (i.e., expired). Each patient's medical record was evaluated for a subset of demographics and clinical variables. Given that patients who undergo surgical resection of meningiomas have a national median LOS of 6 days, we subdivided the patients into 2 cohorts: early discharge (LOS < 3) and late discharge (LOS ≥ 3). Statistical analysis was performed using SPSS 21.0 to assess the significance of the results. RESULTS:We identified 139 (25 male, 114 female) meningioma patients who underwent surgical resection. Seventy of these patients had surgery during the early week (defined as Monday-Wednesday), and 69 had surgery in the later week (Thursday-Friday). The median age for both early and late groups was 58, and the median diameter of the tumor was 3.1 cm and 3.3 cm, respectively. Overall, 55% of the patients had public insurance and 43% had private insurance, with no significant variation between the early and late groups. The median LOS for the early and late populations was 3 and 4 days, respectively. Physical therapy recommendations for rehabilitation facility were made in 26% of early-week patients and in 42% of late-week patients. Additionally, we found a statistically significant decreased LOS (<3 days) in those patients who underwent surgery during the early week (Monday-Wednesday), as opposed to those who received surgery in the later week (Thursday, Friday) (P = 0.045, Mann-Whitney test). CONCLUSION/CONCLUSIONS:Day of surgery may play a significant role in LOS for meningioma patients. Clinicians should remain aware of those factors that may delay optimal patient discharge and early access to rehabilitation facilities. Further studies will need to be performed to assess the social variables that may affect LOS, as well as the financial implications for such extended hospital courses.

BACKGROUND:Recent decades have seen a rapid expansion of involvement of medical students in biomedical research during medical school training. Research within medical school has been shown to influence medical students with regard to medical knowledge, career development, and residency specialty choice. The objective of this study was to evaluate the impact of neurosurgery medical student research grants on neurosurgery residency choice and provide an insight on the demographics of grant awardees. METHODS:In this retrospective study, a search of award recipients was performed using data available on the American Association of Neurological Surgeons, Congress of Neurological Surgeons, and Neurosurgery Research and Education Foundation websites. Searched years included the first cycle of American Association of Neurological Surgeons/Neurosurgery Research and Education Foundation (2007) and Council of State Neurosurgical Societies/Congress of Neurological Surgeons (2008-2009) grant awards until the 2015-2016 cycle, which is the latest award cycle to date. RESULTS:The initial search yielded 163 research grants that were awarded to 158 students between the years of 2007 and 2016. Among the 163 grant recipients, 126 (77.3%) were men. Among the 88 recipients who entered postgraduate residency programs, 51% (45 of 88) matched into neurosurgery residency. When considering both neurosurgery and neurology residency programs, the percentage increased to 59.1% (52 of 88). CONCLUSIONS:Neurosurgery grants for medical students are highly successful in producing future neurosurgeons with >50% of grant recipients matched into neurosurgery. Women are underrepresented in neurosurgery grants and neurosurgery residency programs. This situation can be improved by providing insight about the field early in medical school, perhaps through increased use of neurosurgery medical student grants.

Objective  Traditional techniques for resection of lumbar plexus tumors have been associated with approach-related morbidity. We describe a case utilizing a minimally invasive transpsoas lateral access approach to resect a retroperitoneal tumor of the lumbar plexus. Methods  We report a case with an extradural retroperitoneal schwannoma of the L4 nerve root that was treated with a minimally invasive direct lateral transpsoas approach using atraumatic tissue dilators and an expandable tubular retractor. The use of directional and continuous electromyographic monitoring was critical in locating the plexus and positioning the retractor immediately anterior to the tumor. Results  The patient tolerated the procedure well without postoperative complications. The operative approach was direct and intraoperative blood loss was negligible. The patient demonstrated improved left leg strength and ambulation and resolution of paresthesias. Conclusions  A minimally invasive direct lateral transpsoas access approach is an effective technique to safely and adequately resect extradural retroperitoneal lumbar plexus tumors.

Predictions of patient outcomes after a given therapy are fundamental to medical practice. We employ a machine learning approach towards predicting the outcomes after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). Using three prospective databases, a machine learning approach of feature engineering and model optimization was implemented to create the most accurate predictor of AVM outcomes. Existing prognostic systems were scored for purposes of comparison. The final predictor was secondarily validated on an independent site's dataset not utilized for initial construction. Out of 1,810 patients, 1,674 to 1,291 patients depending upon time threshold, with 23 features were included for analysis and divided into training and validation sets. The best predictor had an average area under the curve (AUC) of 0.71 compared to existing clinical systems of 0.63 across all time points. On the heldout dataset, the predictor had an accuracy of around 0.74 at across all time thresholds with a specificity and sensitivity of 62% and 85% respectively. This machine learning approach was able to provide the best possible predictions of AVM radiosurgery outcomes of any method to date, identify a novel radiobiological feature (3D surface dose), and demonstrate a paradigm for further development of prognostic tools in medical care.

BACKGROUND: For patients with brain metastases, systemic disease burden has historically been accepted as a major determinant of overall survival (OS). However, less research has focused on specific history and physical findings made by clinicians and how such findings pertain to patient outcomes at a given time point. The aim of this study is to determine how the initial clinical assessment of patients with brain metastases, as part of the history and physical at the time of consultation, correlates to patient prognosis. METHODS: We evaluated a prospective, multi-institutional database of 1523 brain metastases in 507 patients who were treated with radiosurgery (Gamma Knife or CyberKnife) from 2001 to 2014. Relevant history of present illness (HPI) and past medical history (PMH) variables included comorbidities, Eastern Cooperative Oncology Group (ECOG) performance status, and seizure history. Physical exam findings included a sensory exam, motor exam, and cognitive function. Univariate and multivariate Cox regression analyses were used to identify predictors of OS. RESULTS: Two hundred ninety-four patients were included in the final analysis with a median OS of 10.8 months (95% CI, 7.8-13.7 months). On univariate analysis, significant HPI predictors of OS included age, primary diagnosis, performance status, extracranial metastases, systemic disease status, and history of surgery. Significant predictors of OS from the PMH included cardiac, vascular, and infectious comorbidities. On a physical exam, findings consistent with cognitive deficits were predictive of worse OS. However, motor deficits or changes in vision were not predictive of worse OS. In the multivariate Cox regression analysis, predictors of worse OS were primary diagnosis (p = 0.002), ECOG performance status (OR 1.73, p < 0.001), and presence of extracranial metastases (OR 1.22, p = 0.009). CONCLUSION: Neurological deficits and systemic comorbidities noted at presentation are not associated with worse overall prognosis for patients with brain metastases undergoing radiosurgery. When encountering new patients with brain metastases, the most informative patient-related characteristics that determine prognosis remain performance status, primary diagnosis, and extent of extracranial disease.

BACKGROUND:Achieving durable local control while limiting normal tissue toxicity with definitive radiation therapy in the management of high-risk brain metastases remains a radiobiological challenge. The objective of this study was to examine the local control and toxicity of a 5-fraction stereotactic radiosurgical approach for treatment of patients with inoperable single high-risk NSCLC brain metastases. METHODS:This retrospective analysis examines 20 patients who were deemed to have "high-risk" brain metastases. High-risk tumors were defined as those with a maximum diameter greater than 2 cm and/or those located within an eloquent cortex. Patients were evaluated by a neurosurgeon prior to treatment and determined to be inoperable due to tumor or patient characteristics. Patients were treated using the CyberKnife® SRS system in 5 fractions to a total dose of 30 Gy, 35 Gy, or 40 Gy. RESULTS:Twenty patients with a median age of 65.5 years were treated from April 2010 to August 2014 in 5 fractions to a median total dose of 35 Gy. At a median follow up of 11.3 months local tumor control was observed in 18 of 20 metastases (90 %). Both local failures were observed in patients receiving a lower dose of 30 Gy. Median pre-treatment dexamethasone dose was 10 mg/day and median post-treatment nadir dose was 0 mg/day. Salvage intracranial therapy was required in 45 % of patients. Symptomatic radionecrosis was observed in 4 of 20 patients (20 %), two of which were treated to 40 Gy and the remainder to 35 Gy. Kaplan-Meier 1-year, 2-year, and median survival were calculated to be 45 %, 20 %, and 13.2 months, respectively. CONCLUSIONS:Five-fraction SRS to a total dose of 35 Gy appears to be a safe and effective management strategy for single high-risk NSCLC brain metastases, while a total dose of 40 Gy leads to an excess risk of neurotoxicity.

BACKGROUND: Embolization before stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVM) has been shown to negatively affect obliteration rates, but its impact on the risks of radiosurgery-induced complications and latency period hemorrhage is poorly defined. OBJECTIVE: To determine, in a case-control study, the effect of prior embolization on AVM SRS outcomes. METHODS: We evaluated a database of AVM patients who underwent SRS. Propensity score analysis was used to match the case (embolized nidi) and control (nonembolized nidi) cohorts. AVM angioarchitectural complexity was defined as the sum of the number of major feeding arteries and draining veins to the nidus. Multivariate Cox proportional hazards regression analyses were performed on the overall study population to determine independent predictors of obliteration and radiation-induced changes. RESULTS: The matching process yielded 242 patients in each cohort. The actuarial obliteration rates were significantly lower in the embolized (31%, 49% at 5, 10 years, respectively) compared with the nonembolized (48%, 64% at 5, 10 years, respectively) cohort (P = .003). In the multivariate analysis for obliteration, lower angioarchitectural complexity (P < .001) and radiologically evident radiation-induced changes (P = .016) were independent predictors, but embolization was not significant (P = .744). In the multivariate analysis for radiologic radiation-induced changes, lack of prior embolization (P = .009) and fewer draining veins (P = .011) were independent predictors. CONCLUSION: The effect of prior embolization on AVM obliteration after SRS may be significantly confounded by nidus angioarchitectural complexity. Additionally, embolization could reduce the risk of radiation-induced changes. Thus, combined embolization and SRS may be warranted for appropriately selected nidi. ABBREVIATIONS: AVM, arteriovenous malformationRBAS, radiosurgery-based AVM scoreSRS, stereotactic radiosurgeryVRAS, Virginia Radiosurgery AVM Scale.

INTRODUCTION/BACKGROUND:Although approximately one in every 10 patients undergoing coil embolization of intracranial aneurysms requires retreatment, the factors that are associated with outcome following retreatment remain to be fully elucidated. METHODS:This is a single-center, retrospective review of 43 patients with 58 intracranial aneurysms that were retreated from 2004 to 2014. Aneurysms undergoing first time or microsurgical retreatment were excluded. Retreatment types were grouped into those without permanent parent vessel support (stand-alone and balloon-assisted coiling) versus those with permanent parent vessel support (stent-assisted coiling, stand-alone stenting, and flow diversion). The Modified Raymond Roy Classification was used to group aneurysms at all angiographic follow-up points either in the successful outcome group (Class I or II) or the unsuccessful outcome group (Class IIIa or IIIb). RESULTS:Of aneurysms with follow-up, 50% were in the successful group and 50% in the unsuccessful group. In univariate analysis, small aneurysm size (p < 0.001), previous treatment type (p = 0.022), retreatment type (p = 0.001), and initial occlusion class (p = 0.005) were all associated with angiographic outcome. In multivariate analysis, small aneurysm size (p = 0.005, odds ratio (OR) 24.56, confidence interval (CI) 2.68-225.4) and retreatment type with permanent parent vessel support, namely stent-assisted coiling (p = 0.017, OR 31.1, CI 1.89-517.7), were associated with retreatment success. CONCLUSIONS:Small aneurysm size and retreatment with permanent parent vessel support, namely stent-assisted coiling, are predictors of success following endovascular retreatment of intracranial aneurysms. These findings could be useful in the effort to both prevent and predict treatment failure following endovascular retreatment.

We present a retrospective review of 357 consecutive patients with 419 aneurysms treated with coil embolization. Although incomplete occlusion and recurrence of intracranial aneurysms following coil embolization is a well-known problem, the factors that influence and predict treatment failure are still debated. For this study, we excluded non-coiling endovascular techniques (flow diversion) and non-saccular aneurysms (fusiform). The modified Raymond-Roy occlusion classification (MRRC) was used to grade the aneurysms. Treatment failure was defined as filling of the aneurysm dome (MRRC Class IIIa or IIIb) at the first angiographic follow-up (average 8 months). Univariate statistical tests were employed to select variables for incorporation into a multivariable logistic regression model. Multivariate analysis identified greater aneurysm volume (p<0.001), packing density (PD) less than 31% (p=0.007) and initial MRRC Class IIIb (p<0.001) as predictors of treatment failure. Incomplete neck coverage with coils was associated with treatment failure in univariate but not multivariate analysis. Class IIIb status was more predictive of treatment failure compared to all Class III (odds ratio 168 versus 14.4). Clinical outcomes were similar in both groups except that there were more retreatments in the treatment failure group (p<0.001). Aneurysm volume, PD and initial occlusion class are associated with angiographic outcome, consistent with prior literature. The MRRC is a powerful predictor of treatment failure. These results will be useful in the effort to both prevent and predict treatment failure after coil embolization, however, they should be verified in a prospective study.

Cervical-petrous internal carotid artery (CP-ICA) pseudoaneurysms are rare and have different etiologies, presentations, and treatment options. A middle-aged patient with a history of chronic otitis media presented with acute otorrhagia and was found to have a left-sided CP-ICA pseudoaneurysm. The patient was a poor surgical candidate with difficult arterial access. The pseudoaneurysm was treated with stand-alone coiling via a left brachial approach with persistent contrast filling seen only in the aneurysm neck at the end of the procedure. The patient re-presented 12 days later with repeat hemorrhage and rapid enlargement of the neck remnant, and was treated with a covered stent via a transcervical common carotid artery cut-down. A covered stent may provide a more definitive treatment for CP-ICA pseudoaneurysms compared with standalone coiling.