Spinal column shortening with single-stage prone lateral vertebral osteotomy for tethered cord syndrome: illustrative case.

BACKGROUND: Tethered cord syndrome (TCS) is a rare neurological disorder characterized by longitudinal stretching on the distal end of the spinal cord. The condition commonly manifests in lumbosacral and lower-extremity pain and weakness, sensory disturbances, and incontinence. Traditionally, tethered cord release has been the first-line management for TCS, but retethering and complications such as cerebrospinal fluid leakage are commonly reported. As a result, spinal column shortening (SCS) vertebral osteotomy has emerged as a potential alternative. OBSERVATIONS: Herein, the authors describe the first single-stage prone lateral SCS vertebral osteotomy with simultaneous posterior exposure in a 48-year-old male patient with multiple prior direct detethering procedures. The authors highlight the case presentation, operative technique, and postoperative course. Following surgery, there were no immediate surgical complications, and the patient noted clinical improvement in his radicular pain and neurological function. LESSONS: This case further supports SCS vertebral osteotomy as an effective treatment option for patients with TCS. It also demonstrates the potential for a single-stage lateral approach with posterior exposure as a minimally invasive option for spinal shortening procedures. However, further studies using expanded cohorts and assessing various surgical techniques are warranted. https://thejns.org/doi/10.3171/CASE24185.

ALARA principles in practice: reduced frame and pulse rates for middle meningeal artery embolization.

Objective: As the prevalence of neuroendovascular interventions increases, it is critical to mitigate unnecessary radiation for patients, providers, and health care staff. Our group previously demonstrated reduced radiation dose and exposure during diagnostic angiography by reducing the default pulse and frame rates. We applied the same technique for basic neuroendovascular interventions. Methods: We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. We studied consecutive, unilateral middle meningeal artery embolizations treated with particles. Total radiation dose, radiation per angiographic run, total radiation exposure, and exposure per run were calculated. Multivariable log-linear regression was performed to account for patient body mass index (BMI), number of angiographic runs, and number of vessels catheterized. Results: A total of 20 consecutive, unilateral middle meningeal artery embolizations were retrospectively analyzed. The radiation reduction protocol was associated with a 39.2% decrease in the total radiation dose and a 37.1% decrease in radiation dose per run. The protocol was associated with a 41.6% decrease in the total radiation exposure and a 39.5% decrease in exposure per run. Conclusions: Radiation reduction protocols can be readily applied to neuroendovascular interventions without increasing overall fluoroscopy time and reduce radiation dose and exposure by 39.2% and 41.6% respectively. We strongly encourage all interventionalists to be cognizant of pulse rate and frame rate when performing routine interventions.

Reducing frame rate and pulse rate for routine diagnostic cerebral angiography: ALARA principles in practice.

OBJECTIVE: Diagnostic cerebral angiograms (DCAs) are widely used in neurosurgery due to their high sensitivity and specificity to diagnose and characterize pathology using ionizing radiation. Eliminating unnecessary radiation is critical to reduce risk to patients, providers, and health care staff. We investigated if reducing pulse and frame rates during routine DCAs would decrease radiation burden without compromising image quality. METHODS: We performed a retrospective review of prospectively acquired data after implementing a quality improvement protocol in which pulse rate and frame rate were reduced from 15 p/s to 7.5 p/s and 7.5 f/s to 4.0 f/s respectively. Radiation doses and exposures were calculated. Two endovascular neurosurgeons reviewed randomly selected angiograms of both doses and blindly assessed their quality. RESULTS: A total of 40 consecutive angiograms were retrospectively analyzed, 20 prior to the protocol change and 20 after. After the intervention, radiation dose, radiation per run, total exposure, and exposure per run were all significantly decreased even after adjustment for BMI (all p<0.05). On multivariable analysis, we identified a 46% decrease in total radiation dose and 39% decrease in exposure without compromising image quality or procedure time. CONCLUSIONS: We demonstrated that for routine DCAs, pulse rate of 7.5 with a frame rate of 4.0 is sufficient to obtain diagnostic information without compromising image quality or elongating procedure time. In the interest of patient, provider, and health care staff safety, we strongly encourage all interventionalists to be cognizant of radiation usage to avoid unnecessary radiation exposure and consequential health risks.

Helical coils augment embolization of the middle meningeal artery for treatment of chronic subdural hematoma: A technical note.

Embolization of the middle meningeal artery (MMA) is a safe and effective adjunct in the treatment of chronic subdural hematoma. While prior authors describe the use of coils to assist embolization by preventing reflux through eloquent collaterals, we de- scribe the use of coils to further open the MMA, allowing the administration of greater amounts of embolisate for a more robust embolization. The objective of this study was to demonstrate that helical coils can safely open the MMA following the administration of polyvinyl alcohol (PVA) particles. This allows for more embolisate to be administered into the MMA for more effective treatment. A retrospective review was conducted at our institution including intraoperative images and postoperative clinical and radiographic follow up. Failure rates using MMA embolization with PVA and helical coil augmentation were compared to failure rates in the literature of MMA embolization with PVA or ethylene vinyl-alcohol copolymer alone. A total of 8 cases were reviewed in which this technique was implemented. There were no immediate complications after treatment. All patients that underwent helical coil embolization following the administration of PVA had increased amount of embolisate delivered into the MMA. All patients at follow up had resolution of the subdural hematoma on outpatient imaging. Helical coil embolization allows for more embolisate administration into the MMA and provides a technical advantage for patients that fail traditional techniques of embolization. Case series are taking place to further test this hypothesis and identify the ideal patient population that may gain maximal yield from this novel technique.

Robotics and Artificial Intelligence in Endovascular Neurosurgery.

The use of artificial intelligence (AI) and robotics in endovascular neurosurgery promises to transform neurovascular care. We present a review of the recently published neurosurgical literature on artificial intelligence and robotics in endovascular neurosurgery to provide insights into the current advances and applications of this technology. The PubMed database was searched for "neurosurgery" OR "endovascular" OR "interventional" AND "robotics" OR "artificial intelligence" between January 2016 and August 2021. A total of 1296 articles were identified, and after applying the inclusion and exclusion criteria, 38 manuscripts were selected for review and analysis. These manuscripts were divided into four categories: 1) robotics and AI for the diagnosis of cerebrovascular pathology, 2) robotics and AI for the treatment of cerebrovascular pathology, 3) robotics and AI for training in neuroendovascular procedures, and 4) robotics and AI for clinical outcome optimization. The 38 articles presented include 23 articles on AI-based diagnosis of cerebrovascular disease, 10 articles on AI-based treatment of cerebrovascular disease, two articles on AI-based training techniques for neuroendovascular procedures, and three articles reporting AI prediction models of clinical outcomes in vascular disorders of the brain. Innovation with robotics and AI focus on diagnostic efficiency, optimizing treatment and interventional procedures, improving physician procedural performance, and predicting clinical outcomes with the use of artificial intelligence and robotics. Experimental studies with robotic systems have demonstrated safety and efficacy in treating cerebrovascular disorders, and novel microcatheterization techniques may permit access to deeper brain regions. Other studies show that pre-procedural simulations increase overall physician performance. Artificial intelligence also shows superiority over existing statistical tools in predicting clinical outcomes. The recent advances and current usage of robotics and AI in the endovascular neurosurgery field suggest that the collaboration between physicians and machines has a bright future for the improvement of patient care. The aim of this work is to equip the medical readership, in particular the neurosurgical specialty, with tools to better understand and apply findings from research on artificial intelligence and robotics in endovascular neurosurgery.

Practices and Patterns of Hourly Neurochecks: Analysis of 8,936 Patients With Neurological Injury.

BACKGROUND: Patients experiencing acute neurological injury often receive hourly neurological assessments ("neurochecks") to capture signs of deterioration. While commonly utilized in the intensive care unit (ICU) setting, little is known regarding practices (i.e., variations by age and ordering services) and patterns (i.e., duration and post-discontinuation plans) of hourly neurochecks. To inform future quality improvement intervention efforts, we performed an analysis of hourly neurochecks using an electronic health record-based dataset. STUDY DESIGN AND METHODS: Our 75-month retrospective dataset consisted of all health system ICU patients who received hourly neurochecks. Variables included age, admission diagnosis category, ordering provider, post-discontinuation order, and discharge destination. Multivariable Cox regression was used to evaluate factors associated with hourly neurocheck duration. RESULTS: We evaluated 9,513 first admission hourly neurocheck orders in 8,936 patients. The trauma, neurosurgery, and neurocritical care services were responsible for 4,067 (43%), 2,071 (22%) and 1,697 (18%) hourly neurocheck orders, respectively. Median (interquartile range) hourly neurocheck duration was 1.09 (0.69, 2.35) days, and was greater than 3 and 7 days, respectively, for 1,773 (19%) and 640 (7%) patients. Median hourly neurocheck duration ranged from 0.87 (0.65, 1.68) to 1.60 (0.83, 2.97) days for neurosurgical and non-neurological ICU services, respectively. Upon discontinuation, 2,225 (23%) of hourly neurochecks were transitioned to no neurochecks. CONCLUSION: Substantial differences exist between ICU services and practice patterns surrounding hourly neurochecks. Understanding these differences will help inform intervention efforts aimed at streamlining hourly neurocheck practices and outcomes for patients with acute neurological injury.

Cumulative Intracranial Tumor Volume as a Prognostic Factor in Patients with Brain Metastases Undergoing Stereotactic Radiosurgery.

Approximately 25-35% of all cancer patients suffer from brain metastases (BM), and many of them-in particular, those with a limited number of intracranial tumors-are treated with stereotactic radiosurgery (SRS). Accurate prediction of survival remains a key clinical challenge in this population. Several prognostic scales have been developed to facilitate this prognostication, including the Recursive Partitioning Analysis (RPA) classification, the modified Recursive Partitioning Analysis (mRPA) subclassifications, the Basic Score for Brain Metastases (BS-BM), the Score Index for Radiosurgery (SIR), the Graded Prognostic Assessment (GPA), and the diagnosis-specific Graded Prognostic Assessment (dsGPA). However, none of these scales include consideration of the cumulative intracranial tumor volume (CITV), which is defined as the sum of all intracranial tumor volumes. Since there is mounting evidence that the CITV carries significant prognostic value in SRS-treated patients with BM, this variable should be considered during survival prognostication, along with other pertinent clinical, pathological, and molecular characteristics.

Engorged venous plexus mimicking adjacent segment disease: Case report and review of the literature.

BACKGROUND: An engorged venous plexus may mimic nerve compression from a herniated disk on the magnetic resonance (MR) studies as they both have similar signal intensities. During a laminectomy, if an engorged venous plexus is encountered instead of a disk herniation, there may be marked unanticipated bleeding. CASE DESCRIPTION: A 58-year-old female who had a prior anterior lumbar interbody fusion later returned with recurrent radiculopathy. Adjacent segment disease from a spinal disk herniation was suspected based on the surgical history, physical examination, and imaging (MRI) findings. Rather than a disk, an engorged venous plexuses (EVP) was encountered intraoperatively. CONCLUSION: Here, we discussed our findings regarding a lumbar EVP rather than a herniated disk and reviewed the current literature. Although rare, a higher index of suspicion for these vascular malformations based on combined historical information and MRI studies should allow one to better detect and/or anticipate an EVP rather than a routine disk.

The Potential Impact of "Take the Volume Pledge" on Outcomes After Carotid Artery Stenting.

BACKGROUND: The "Volume Pledge" aims to centralize carotid artery stenting (CAS) to hospitals and surgeons performing ≥10 and ≥5 procedures annually, respectively. OBJECTIVE: To compare outcomes after CAS between hospitals and surgeons meeting or not meeting the Volume Pledge thresholds. METHODS: We queried the Nationwide Inpatient Sample for CAS admissions. Hospitals and surgeons were categorized as low volume and high volume (HV) based on the Volume Pledge. Multivariable hierarchical regression models were used to examine the impact of hospital volume (2005-2011) and surgeon volume (2005-2009) on perioperative outcomes. RESULTS: Between 2005 and 2011, 22 215 patients were identified. Most patients underwent CAS by HV hospitals (86.4%). No differences in poor outcome (composite endpoint of in-hospital mortality, postoperative neurological or cardiac complications) were observed by hospital volume but HV hospitals did decrease the likelihood of other complications, nonroutine discharge, and prolonged hospitalization. From 2005 to 2009, 9454 CAS admissions were associated with physician identifiers. Most patients received CAS by HV surgeons (79.2%). On multivariable analysis, hospital volume was not associated with improved outcomes but HV surgeons decreased odds of poor outcome (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.59-0.97; P = .028), complications (OR 0.56, 95% CI 0.46-0.71, P < .001), nonroutine discharge (OR 0.70, 95% CI 0.57-0.87; P = .001), and prolonged hospitalization (OR 0.52, 95% 0.44-0.61, P < .001). CONCLUSION: Most patients receive CAS by hospitals and providers meeting the Volume Pledge threshold for CAS. Surgeons but not hospitals who met the policy's volume standards were associated with superior outcomes across all measured outcomes.

National Trends in the Surgical Management of Lumbar Spinal Stenosis in Adult Spinal Deformity Patients.

STUDY DESIGN: This is a retrospective analysis of national administrative hospital data. OBJECTIVE: This study examines national trends in the surgical management of lumbar spinal stenosis (LSS) in patients with and without coexisting scoliosis between 2010 and 2014. The study also examines revision rates for LSS procedures. SUMMARY OF BACKGROUND DATA: There is wide variability in the surgical management of patients with LSS, with and without coexisting spinal deformity. METHODS: Data were obtained from the Healthcare Cost and Utilization Project's National Inpatient Sample Database. International Classification of Diseases 9th revision- Clinical Modification codes were used to identify all patients with a primary diagnosis of lumbar spinal stenosis. These patients were divided into two groups: 1) LSS alone and 2) LSS with coexisting scoliosis. The two groups were examined for one of three surgical outcomes: 1) decompression alone (discectomy, laminectomy), 2) simple fusion, and 3) complex fusion (>three vertebrae or 360° fusion). The groups were then further examined for revision operations. National Inpatient Sample discharge weights were applied where relevant. RESULTS: In 2014 national estimates of discharged patients indicated 76,275 patients with a primary diagnosis of LSS (population rate, 23.9; in the elderly (65+) the age-adjusted population rate was 95.4). Of these patients, 88.5% were managed through primary surgery (34.6% decompression, 47.2% simple fusion, 5.7% complex fusion). Between 2010 and 2014, the percentage of decompression decreased from 47.5% to 34.6%, the percent of simple fusion increased from 35.3% to 47.2%, and the percent of complex fusion increased from 5.7% to 7.1% (P < 0.01). In patients with coexisting scoliosis, lumbar spinal stenosis was predominantly managed by simple fusion and complex fusion (15.5% decompression, 51.9% simple fusion, 27.3% complex fusion, in 2014). Revision rates were highest among patients without scoliosis managed with complex fusion (15.8% in 2014) compared with patients with scoliosis (8.8% in 2014). Patients with scoliosis who underwent decompression only had revision rates of 1.7% and 0.62% in 2010 and 2014, respectively. CONCLUSION: We observed a leveling-off of the rate of operation for patients with a primary diagnosis of LSS at around 88%. There was an increase in the rate of fusion and a decrease in the rate of decompression across all patient groups. We report no difference in revision rates between patients with and without scoliosis, except in those undergoing a complex fusion. LEVEL OF EVIDENCE: 3.

The effect of hospital safety-net burden on outcomes, cost, and reportable quality metrics after emergent clipping and coiling of ruptured cerebral aneurysms.

OBJECTIVE: Safety-net hospitals deliver care to a substantial share of vulnerable patient populations and are disproportionately impacted by hospital payment reform policies. Complex elective procedures performed at safety-net facilities are associated with worse outcomes and higher costs. The effects of hospital safety-net burden on highly specialized, emergent, and resource-intensive conditions are poorly understood. The authors examined the effects of hospital safety-net burden on outcomes and costs after emergent neurosurgical intervention for ruptured cerebral aneurysms. METHODS: The authors conducted a retrospective analysis of the Nationwide Inpatient Sample (NIS) from 2002 to 2011. Patients ≥ 18 years old who underwent emergent surgical clipping and endovascular coiling for aneurysmal subarachnoid hemorrhage (SAH) were included. Safety-net burden was defined as the proportion of Medicaid and uninsured patients treated at each hospital included in the NIS database. Hospitals that performed clipping and coiling were stratified as low-burden (LBH), medium-burden (MBH), and high-burden (HBH) hospitals. RESULTS: A total of 34,647 patients with ruptured cerebral aneurysms underwent clipping and 23,687 underwent coiling. Compared to LBHs, HBHs were more likely to treat black, Hispanic, Medicaid, and uninsured patients (p < 0.001). HBHs were also more likely to be associated with teaching hospitals (p < 0.001). No significant differences were observed among the burden groups in the severity of subarachnoid hemorrhage. After adjusting for patient demographics and hospital characteristics, treatment at an HBH did not predict in-hospital mortality, poor outcome, length of stay, costs, or likelihood of a hospital-acquired condition. CONCLUSIONS: Despite their financial burden, safety-net hospitals provide equitable care after surgical clipping and endovascular coiling for ruptured cerebral aneurysms and do not incur higher hospital costs. Safety-net hospitals may have the capacity to provide equitable surgical care for highly specialized emergent neurosurgical conditions.

Association between medical academic genealogy and publication outcome: impact of unconscious bias on scientific objectivity.

BACKGROUND: Our previous studies suggest that the training history of an investigator, termed "medical academic genealogy", influences the outcomes of that investigator's research. Here, we use meta-analysis and quantitative statistical modeling to determine whether such effects contribute to systematic bias in published conclusions. METHODS: A total of 108 articles were identified through a comprehensive search of the high-grade glioma (HGG) surgical resection literature. Analysis was performed on the 70 articles with sufficient data for meta-analysis. Pooled estimates were generated for key academic genealogies. Monte Carlo simulations were performed to determine whether the effects attributed to genealogy alone can arise due to chance alone. RESULTS: Meta-analysis of the HGG literature without consideration for academic medical genealogy revealed that gross total resection (GTR) was associated with a significant decrease in the odds ratio (OR) for the hazard of death after surgery for both anaplastic astrocytoma (AA) and glioblastoma (AA: log [OR] = - 0.04, 95% CI [- 0.07 to - 0.01]; glioblastoma log [OR] = - 0.36, 95% CI [- 0.44 to - 0.29]). For the glioblastoma literature, meta-analysis of articles contributed by members of a genealogy consisting of mostly radiation oncologists revealed no reduction in the hazard of death after GTR [log [OR] = - 0.16, 95% CI [- 0.41 to 0.09]. In contrast, meta-analysis of published articles contributed by members of a genealogy consisting of mostly neurosurgeons revealed that GTR was associated with a significant reduction in the hazard of death [log [OR] = - 0.29, 95% CI [- 0.40 to 0.18]. Monte Carlo simulation revealed that the observed discrepancy between the articles contributed by the members of these two genealogies was unlikely to arise by chance alone (p < 0.006). CONCLUSIONS: Meta-analysis of articles contributed by authors belonging to the different medical academic genealogies yielded distinct and contradictory pooled point-estimates, suggesting that genealogy contributes to systematic bias in the published literature.

Prognostic Importance of Cumulative Intracranial Tumor Volume in Patients with Gastrointestinal Brain Metastasis Treated with Stereotactic Radiosurgery.

BACKGROUND: The disease-specific Graded Prognostic Assessment (ds-GPA) for patients with gastrointestinal (GI) tract cancer brain metastases (BM) suggests Karnofsky Performance Status (KPS) as the only pertinent prognostic factor. We evaluated the prognostic importance of cumulative intracranial tumor volume (CITV). METHODS: KPS, CITV, and overall survival were collected from consecutive patients with stereotactic radiosurgery-treated GI BM. Patients were grouped into 2 independent cohorts for development and validation of the model (termed "exploratory" and "validation" cohorts). Analyses were performed using logistic regression, Cox proportional hazards models, Net Reclassification Index (NRI >0), integrated discrimination improvement (IDI >0), and Akaike information criterion. RESULTS: In univariable logistic regression models, both CITV and KPS were independently associated with patient survival. The association between CITV and overall survival remained robust after controlling for KPS (P < 0.001) in a multivariable Cox proportional hazards model. Based on NRI analysis of the exploratory cohort, we found that a CITV cutoff of 12 cm3 best augments the prognostic accuracy of GI-ds-GPA. In this analysis, incorporation of CITV (as < or ≥12 cm3) improved prognostication of the GI-specific GPA model by NRI >0 of 0.397 (95% confidence interval [CI], 0.165-0.630; P < 0.001) and IDI of 0.019 (95% CI, 0.004-0.033; P = 0.013). We confirmed the prognostic usefulness of the CITV-incorporated GI-ds-GPA in an independent validation cohort, in which CITV incorporation improved prognostic usefulness with an NRI >0 of 0.478 (95% CI, 0.257-0.699; P < 0.001) and IDI of 0.028 (95% CI, 0.014-0.043; P < 0.001). CONCLUSIONS: CITV is an important prognostic variable in patients with stereotactic radiosurgery-treated GI BM and augments the prognostic accuracy of the GI-ds-GPA index.

Markov modeling for the neurosurgeon: a review of the literature and an introduction to cost-effectiveness research.

OBJECTIVE Markov modeling is a clinical research technique that allows competing medical strategies to be mathematically assessed in order to identify the optimal allocation of health care resources. The authors present a review of the recently published neurosurgical literature that employs Markov modeling and provide a conceptual framework with which to evaluate, critique, and apply the findings generated from health economics research. METHODS The PubMed online database was searched to identify neurosurgical literature published from January 2010 to December 2017 that had utilized Markov modeling for neurosurgical cost-effectiveness studies. Included articles were then assessed with regard to year of publication, subspecialty of neurosurgery, decision analytical techniques utilized, and source information for model inputs. RESULTS A total of 55 articles utilizing Markov models were identified across a broad range of neurosurgical subspecialties. Sixty-five percent of the papers were published within the past 3 years alone. The majority of models derived health transition probabilities, health utilities, and cost information from previously published studies or publicly available information. Only 62% of the studies incorporated indirect costs. Ninety-three percent of the studies performed a 1-way or 2-way sensitivity analysis, and 67% performed a probabilistic sensitivity analysis. A review of the conceptual framework of Markov modeling and an explanation of the different terminology and methodology are provided. CONCLUSIONS As neurosurgeons continue to innovate and identify novel treatment strategies for patients, Markov modeling will allow for better characterization of the impact of these interventions on a patient and societal level. The aim of this work is to equip the neurosurgical readership with the tools to better understand, critique, and apply findings produced from cost-effectiveness research.

Improving Door to Groin Puncture Time for Mechanical Thrombectomy via Iterative Quality Protocol Interventions.

INTRODUCTION: Delays in door to groin puncture time (DGPT) for patients with ischemic stroke caused by acute large vessel occlusions (LVO) are associated with worse clinical outcomes. We present the results of a quality improvement protocol for endovascular stroke treatment at the University of California, San Diego (UCSD) that aimed to minimize DGPT. MATERIALS AND METHODS: Our stroke team implemented a series of quality improvement measures to decrease DGPT, with a target of 90 minutes or less. Sixty-three patients treated at our center were retrospectively divided into three groups based on the date of their intervention as a proxy for the implementation of process improvement protocols: 23 patients treated from July to December 2015, 24 patients treated from January to July 2016, and 16 patients treated from July 2016 to December 2016. Multivariate log-linear and logistic regression analyses were used to assess the predictors of prolonged DGPT and compliance with target DGPT (<90 min), respectively. RESULTS: Date of intervention-a proxy for the implementation of process improvement protocols-was predictive of compliance with target DGPT. Patients treated from July 2016 to December 2016-after the full implementation of process improvements-were 3.2 times more likely to meet or exceed the target DGPT compared to patients treated from July 2015 to December 2015 (p=0.011). When adjusting for potential confounders in a multivariate analysis, patients in the final cohort were associated with shorter DGPT (Exp(B)=0.61, p=0.013) and remained significantly more likely to achieve the DGPT goal (OR=14.2, p=0.007). CONCLUSION: An iterative quality improvement process can significantly improve DGPT. This analysis demonstrates the utility of a formal quality improvement system at an academic comprehensive stroke center.

Cystic Formation After Stereotactic Radiosurgery of Brain Metastasis.

BACKGROUND: Limited information is available on the natural history and etiology of cystic formation after stereotactic radiosurgery (SRS) for brain metastases (BM). We aimed to characterize the natural history of cyst formation after SRS of BM and analyze potential risk factors. METHODS: We retrospectively reviewed 214 consecutive patients who underwent a total of 1106 SRSs for BM. Demographic, clinical, dosimetric, and magnetic resonance imaging MRI data were reviewed. Statistical analysis was accomplished using Student's t test, and univariate and multivariate logistic regression. RESULTS: The median patient age was 61 years (range, 19-91 years), and the median duration of follow-up was 424 days (range, 91-2934 days). Eleven cases of cyst formation (0.9% of 1106 treated lesions) were identified at SRS-treated BM sites among 9 patients (2 patients developed cysts at independent sites). The median interval between first SRS and first evidence of cyst was 218 days. Seven of the 9 patients (78%) sustained progressive cyst expansion and neurologic decline requiring steroid treatment. Four of these 7 patients (57%) experienced continued neurologic decline and needed surgical fenestration. On univariate analysis, receipt of >4 rounds of SRS was the sole variable associated with an increased risk of cyst formation (odds ratio, 16.58; P = 0.001). This association remained robust after adjusting for duration of follow-up (odds ratio, 13.59; P = 0.003). CONCLUSIONS: In our experience with 1106 SRS-treated cases of BM, cyst formation was a rare phenomenon. However, 1 in 3 patients who underwent >4 rounds of SRS sustained cyst formation. A high proportion (78%) of SRS-associated cysts progressively expanded and required medical or surgical treatment.

Cumulative Intracranial Tumor Volume Augments the Prognostic Value of Diagnosis-Specific Graded Prognostic Assessment Model for Survival in Patients with Melanoma Cerebral Metastases.

BACKGROUND: The diagnosis-specific graded prognostic assessment scale (ds-GPA) for patients with melanoma brain metastasis (BM) utilizes only 2 key prognostic variables: Karnofsky performance status and the number of intracranial metastases. We wished to determine whether inclusion of cumulative intracranial tumor volume (CITV) into the ds-GPA model for melanoma augmented its prognostic value. OBJECTIVE: To determine whether or not CITV augments the ds-GPA prognostic scale for melanoma. METHODS: We analyzed the survival pattern of 344 melanoma patients with BM treated with stereotactic radiosurgery (SRS) at separate institutions and validated our findings in an independent cohort of 201 patients. The prognostic value of ds-GPA for melanoma was quantitatively compared with and without the addition of CITV using the net reclassification index (NRI > 0) and integrated discrimination improvement (IDI) metrics. RESULTS: The incorporation of CITV into the melanoma-specific ds-GPA model enhanced its prognostic accuracy. Addition of CITV to the ds-GPA model significantly improved its prognostic value, with NRI > 0 of 0.366 (95% CI: 0.125-0.607, P = .002) and IDI of 0.024 (95% CI: 0.008-0.040, P = .004). We validated these findings that CITV improves the prognostic utility of melanoma ds-GPA in an independent cohort of 201 melanoma cohort. CONCLUSION: The prognostic value of the ds-GPA scale for melanoma BM is enhanced by the incorporation of CITV.

Impact of neurosurgeon specialization on patient outcomes for intracranial and spinal surgery: a retrospective analysis of the Nationwide Inpatient Sample 1998-2009.

OBJECTIVE The subspecialization of neurosurgical practice is an ongoing trend in modern neurosurgery. However, it remains unclear whether the degree of surgeon specialization is associated with improved patient outcomes. The authors hypothesized that a trend toward increased neurosurgeon specialization was associated with improved patient morbidity and mortality rates. METHODS The Nationwide Inpatient Sample (NIS) was used (1998-2009). Patients were included in a spinal analysis cohort for instrumented spine surgery involving the cervical spine ( International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes 81.31-81.33, 81.01-81.03, 84.61-84.62, and 84.66) or lumbar spine (codes 81.04-81.08, 81.34-81.38, 84.64-84.65, and 84.68). A cranial analysis cohort consisted of patients receiving a parenchymal excision or lobectomy operation (codes 01.53 and 01.59). Surgeon specialization was measured using unique surgeon identifiers in the NIS and defined as the proportion of a surgeon's total practice dedicated to cranial or spinal cases. RESULTS A total of 46,029 and 231,875 patients were identified in the cranial and spinal analysis cohorts, respectively. On multivariate analysis in the cranial analysis cohort (after controlling for overall surgeon volume, patient demographic data/comorbidities, hospital characteristics, and admitting source), each percentage-point increase in a surgeon's cranial specialization (that is, the proportion of cranial cases) was associated with a 0.0060 reduction in the log odds of patient mortality (95% CI 0.0034-0.0086) and a 0.0042 reduction in the log odds of morbidity (95% CI 0.0032-0.0052). This resulted in a 15% difference in the predicted probability of mortality for neurosurgeons at the 75th versus the 25th percentile of cranial specialization. In the spinal analysis cohort, each percentage-point increase in a surgeon's spinal specialization was associated with a 0.0122 reduction in the log odds of mortality (95% CI 0.0074-0.0170) and a 0.0058 reduction in the log odds of morbidity (95% CI 0.0049-0.0067). This resulted in a 26.8% difference in the predicted probability of mortality for neurosurgeons at the 75th versus the 25th percentile of spinal specialization. CONCLUSIONS For both spinal and cranial surgery patient cohorts derived from the NIS database, increased surgeon specialization was significantly and independently associated with improved mortality and morbidity rates, even after controlling for overall case volume.

Oligodendroglioma resection: a Surveillance, Epidemiology, and End Results (SEER) analysis.

OBJECTIVE The available evidence suggests that the clinical benefits of extended resection are limited for chemosensitive tumors, such as primary CNS lymphoma. Oligodendroglioma is generally believed to be more sensitive to chemotherapy than astrocytoma of comparable grades. In this study the authors compare the survival benefit of gross-total resection (GTR) in patients with oligodendroglioma relative to patients with astrocytoma. METHODS Using the Surveillance, Epidemiology, and End Results (SEER) Program (1999-2010) database, the authors identified 2378 patients with WHO Grade II oligodendroglioma (O2 group) and 1028 patients with WHO Grade III oligodendroglioma (O3 group). Resection was defined as GTR, subtotal resection, biopsy only, or no resection. Kaplan-Meier and multivariate Cox regression survival analyses were used to assess survival with respect to extent of resection. RESULTS Cox multivariate analysis revealed that the hazard of dying from O2 and O3 was comparable between patients who underwent biopsy only and GTR (O2: hazard ratio [HR] 1.06, 95% confidence interval [CI] 0.73-1.53; O3: HR 1.18, 95% CI 0.80-1.72). A comprehensive search of the published literature identified 8 articles without compelling evidence that GTR is associated with improved overall survival in patients with oligodendroglioma. CONCLUSIONS This SEER-based analysis and review of the literature suggest that GTR is not associated with improved survival in patients with oligodendroglioma. This finding contrasts with the documented association between GTR and overall survival in anaplastic astrocytoma and glioblastoma. The authors suggest that this difference may reflect the sensitivity of oligodendroglioma to chemotherapy as compared with astrocytomas.