Faculty Bibliography

Physicians are being challenged to obtain data for outcomes research and measures of quality practice in medicine. We developed a prospective data collection system (registry) that provides data points across all elements of a neurosurgical stereotactic radiosurgery practice. The registry architecture is scalable and suitable for any aspect of neurosurgical practice. Our purpose was to outline the challenges in creating systems for high quality data acquisition and describe experiences in initial testing and use. Over a two year period, a multicenter team working with software engineers developed a comprehensive radiosurgery registry based on a MS-Sequel(R) server platform. Three neurosurgeons at one center were responsible for final editing. Alpha testing began in September 2012 and server-based beta testing began in February 2013. The major elements included demographics, disease-based items (47 categories for different brain tumors, vascular malformations, and functional disorders) with relevant clinical grading systems, treatment-based items (imaging, physics, clinical), and follow-up data (clinical, imaging, subsequent therapeutics). Nine hundred patients were entered into the registry at one test center, with new entries and follow-up data entered daily at the point of contact. With experience, the mean time for one new entry was 6 minutes. Mean time for one follow-up entry was 45 seconds. The system was made secure for individual use and amenable for both data entry and research. Analytics used different filters to create customized outcomes charts as selected by the user (e.g., survival, neurologic function, complications). A local or multicenter prospective data collection registry was created for use across 47 clinical indications for stereotactic cranial radiosurgery. Further refinement of fields and logic is ongoing. The system is reliable, robust, and allows use of rapid analytical tools. Large medical registries will become widely used for collection and analysis of large data sets and should have broad applicability to many other elements of neurosurgical and medical practice.

BACKGROUND: Symptomatic thoracic disc herniation (TDH) is an uncommon condition with significant treatment risks. OBJECTIVE: To evaluate strategies to avoid and manage complications from thoracic disc surgery. METHODS: All TDH cases by the senior author were retrospectively reviewed from 2000 to 2012. Complications were recorded, together with avoidance and management strategies. To reduce access-related morbidity, a thoracoscopic-tubular retractor approach was developed later in the series. RESULTS: 64 patients were treated for TDH, the majority undergoing an anterior minimally-invasive approach. Complications occurred in 15 patients (23%). Three patients with intercostal neuralgia persisting for >3 months had pain resolution after intercostal nerve blocks and radiofrequency lesioning. Five of the six patients with dural tears during anterior surgery had no further events following dural repair, lumbar drain insertion, and placement of chest tube to water seal. One case of persistent CSF leakage was successfully treated with a laparoscopically-mobilized omental flap. Preoperative metallic marker placement was effective at guiding correct-level surgery. For anterior operations, no pneumothorax occurred with routine chest tube placement. Our approach and techniques evolved based on early experience, allowing us to reduce surgical morbidity. The thoracoscopic-tubular retractor approach was associated with low morbidity (no complications among 13 cases other than temporary intercostal neuralgia). CONCLUSIONS: Several strategies may reduce morbidity from thoracic disc surgery: careful approach selection, preoperative level marking, use a tubular retractor with thoracoscopic guidance, rib resection at the mini-thoracotomy site, routine chest tube placement for anterior operations, and routine lumbar drain insertion in the event of a dural tear. Prospective comparative studies are needed to assess the efficacy of these techniques.

OBJECT The purpose of this study was to evaluate the role of stereotactic radiosurgery (SRS) in the management of intracranial hemangioblastomas. METHODS Six participating centers of the North American Gamma Knife Consortium and 13 Japanese Gamma Knife centers identified 186 patients with 517 hemangioblastomas who underwent SRS. Eighty patients had 335 hemangioblastomas associated with von Hippel-Lindau disease (VHL) and 106 patients had 182 sporadic hemangioblastomas. The median target volume was 0.2 cm(3) (median diameter 7 mm) in patients with VHL and 0.7 cm(3) (median diameter 11 mm) in those with sporadic hemangioblastoma. The median margin dose was 18 Gy in VHL patients and 15 Gy in those with sporadic hemangioblastomas. RESULTS At a median of 5 years (range 0.5-18 years) after treatment, 20 patients had died of intracranial disease progression and 9 patients had died of other causes. The overall survival after SRS was 94% at 3 years, 90% at 5 years, and 74% at 10 years. Factors associated with longer survival included younger age, absence of neurological symptoms, fewer tumors, and higher Karnofsky Performance Status. Thirty-three (41%) of the 80 patients with VHL developed new tumors and 17 (16%) of the106 patients with sporadic hemangioblastoma had recurrences of residual tumor from the original tumor. The 5-year rate of developing a new tumor was 43% for VHL patients, and the 5-year rate of developing a recurrence of residual tumor from the original tumor was 24% for sporadic hemangioblastoma patients. Factors associated with a reduced risk of developing a new tumor or recurrences of residual tumor from the original tumor included younger age, fewer tumors, and sporadic rather than VHL-associated hemangioblastomas. The local tumor control rate for treated tumors was 92% at 3 years, 89% at 5 years, and 79% at 10 years. Factors associated with an improved local tumor control rate included VHL-associated hemangioblastoma, solid tumor, smaller tumor volume, and higher margin dose. Thirteen patients (7%) developed adverse radiation effects (ARE) after SRS, and one of these patients died due to ARE. CONCLUSIONS When either sporadic or VHL-associated tumors were observed to grow on serial imaging studies, SRS provided tumor control in 79%-92% of tumors.

An arteriovenous malformation is a tangle of dysplastic vessels (nidus) fed by arteries and drained by veins without intervening capillaries, forming a high-flow, low-resistance shunt between the arterial and venous systems. Arteriovenous malformations in the brain have a low estimated prevalence but are an important cause of intracerebral haemorrhage in young adults. For previously unruptured malformations, bleeding rates are approximately 1% per year. Once ruptured, the subsequent risk increases fivefold, depending on associated aneurysms, deep locations, deep drainage and increasing age. Recent findings from novel animal models and genetic studies suggest that arteriovenous malformations, which were long considered congenital, arise from aberrant vasculogenesis, genetic mutations and/or angiogenesis after injury. The phenotypical characteristics of arteriovenous malformations differ among age groups, with fistulous lesions in children and nidal lesions in adults. Diagnosis mainly involves imaging techniques, including CT, MRI and angiography. Management includes observation, microsurgical resection, endovascular embolization and stereotactic radiosurgery, alone or in any combination. There is little consensus on how to manage patients with unruptured malformations; recent studies have shown that patients managed medically fared better than those with intervention at short-term follow-up. By contrast, interventional treatment is preferred following a ruptured malformation to prevent rehaemorrhage. Management continues to evolve as new mechanistic discoveries and reliable animal models raise the possibility of developing drugs that might prevent the formation of arteriovenous malformations, induce obliteration and/or stabilize vessels to reduce rupture risk. For an illustrated summary of this Primer, visit: http://go.nature.com/TMoAdn.

Introduction: Disconjugate eye movements have been associated with traumatic brain injury since ancient times. Ocular motility dysfunction may be present in up to 90% of patients with concussion or blast injury. Methods: We developed an algorithm for eye tracking in which the Cartesian coordinates of the right and left pupils are tracked over 200 seconds and compared to each other as a subject watches a short film clip moving inside an aperture on a computer screen. We prospectively eye tracked 64 normal healthy non-injured control subjects and compared findings to 75 trauma subjects with either a positive head CT (n=13), negative head CT (n=39) or non-head injury (n=23) to determine whether eye tracking would reveal the disconjugate gaze associated with both structural brain injury and concussion. Tracking metrics were then correlated to the clinical concussion measure SCAT3 in trauma patients. Results: Five out of five measures of horizontal disconjugacy were increased in positive and negative head CT patients relative to non-injured control subjects. Only one of five vertical disconjugacy measures was significantly increased in brain injured patients relative to controls. Linear regression analysis of all 75 trauma patients demonstrated that three metrics for horizontal disconjugacy negatively correlated with SCAT3 symptom severity score and positively correlated with total Standardized Assessment of Concussion (SAC) score. Abnormal eye tracking metrics improved over time towards baseline in brain injured subjects seen in follow-up. Conclusions: Eye tracking may help quantify the severity of ocular motility disruption associated with concussion and structural brain injury.

OBJECT After initial standard of care management of glioblastoma multiforme (GBM), relatively few proven options remain for patients with unresected progressive tumor. Numerous reports describe the value of radiosurgery, yet this modality appears to remain underutilized. The authors analyzed the outcomes of early adjuvant stereotactic radiosurgery (SRS) for unresected tumor or later salvage SRS for progressive GBM. Radiosurgery was performed as part of the multimodality management and was combined with other therapies. Patients continued to receive additional chemotherapy after SRS and prior to progression being documented. In this retrospective analysis, the authors evaluated factors that affected patient overall survival (OS) and progression-free survival. METHODS Between 1987 and 2008 the authors performed Gamma Knife SRS in 297 patients with histologically proven GBMs. All patients had received prior fractionated radiation therapy, and 66% had undergone one or more chemotherapy regimens. Ninety-six patients with deep-seated unresectable GBMs underwent biopsy only. Of those in whom excision had been possible, resection was considered to be gross total in 68 and subtotal in 133. The median patient age was 58 years (range 23-89 years) and the median tumor volume was 14 cm(3) (range 0.26-84.2 cm(3)). The median prescription dose delivered to the imaging-defined tumor margin was 15 Gy (range 9-25 Gy). The median follow-up duration was 8.6 months (range 1.1-173 months). Cox regression models were used to analyze survival outcomes. Variables examined included age, residual versus recurrent tumor, prior chemotherapy, time to first recurrence, SRS dose, and gross tumor volume. RESULTS The median survival times after radiosurgery and after diagnosis were 9.03 and 18.1 months, respectively. The 1-year and 2-year OS after SRS were 37.9% and 16.7%, respectively. The 1-year and 2-year OS after diagnosis were 76.2% and 30.8%, respectively. Using multivariate analysis, factors associated with improved OS after diagnosis were younger age (< 60 years) at diagnosis (p < 0.0001), tumor volume < 14 cm(3) (p < 0.001), use of prior chemotherapy (p = 0.001), and radiosurgery at the time of recurrence (p < 0.0001). Multivariate analysis showed that younger age (p < 0.0001) and smaller tumor volume (< 14 cm(3)) (p = 0.001) were significantly associated with increased OS after SRS. Adverse radiation effects were seen in 69 patients (23%). Fifty-eight patients (19.5%) underwent additional resection after SRS. The median survivals after diagnosis for recursive partitioning analysis Classes III, IV and V+VI were 31.6, 20.8, and 16.7 months, respectively. CONCLUSIONS In this analysis 30% of a heterogeneous cohort of GBM patients eligible for SRS had an OS of 2 years. Radiosurgery at the time of tumor progression was associated with a median survival of 21.8 months. The role of radiosurgery for GBMs remains controversial. The findings in this study support the need for a funded and appropriately designed clinical trial that will provide a higher level of evidence regarding the future role of SRS for glioblastoma patients in whom disease has progressed despite standard management.

: Meningiomas are among the most common adult brain tumors. Although the optimal management of meningiomas would provide complete elimination of the lesion, this cannot always be accomplished safely through resection. Therefore, other therapeutic modalities, such as stereotactic radiosurgery (as primary or adjunctive therapy), have emerged. In the current review, we have provided an overview of the historical outcomes of various radiosurgical modalities applied in the management of meningiomas. Furthermore, we provide a discussion on key factors (eg World Health Organization grade, lesion size, and lesion location) that affect tumor control and adverse event rates. We discuss recent changes in our understanding of meningiomas, based on molecular and genetic markers, and how these will change our perspective on the management of meningiomas. We conclude by outlining the areas in which knowledge gaps persist and provide suggestions as to how these can be addressed. ABBREVIATIONS: ARE, adverse radiation eventCI, conformity indexFSRT, fractionated radiotherapyGK, Gamma KnifeGTR, gross total resectionHGM, high-grade meningiomaLINAC, linear acceleratorNF2, neurofibromatosis type 2OA, optic apparatusOS, overall survivalPFS, progression-free survivalSRS, stereotactic radiosurgerySTR, subtotal resectionTC, tumor controlVS, vestibular schwannomaWHO, World Health Organization.

OBJECT Physicians are often solicited by patients or colleagues for clinical recommendations they would make for themselves if faced by a clinical situation. The act of making a recommendation can alter the clinical course being taken. The authors sought to understand this dynamic across different neurosurgical scenarios by examining how neurosurgeons value the procedures that they offer. METHODS The authors conducted an online survey using the Congress of Neurological Surgeons listserv in May 2013. Respondents were randomized to answer either as the surgeon or as the patient. Questions encompassed an array of distinct neurosurgical scenarios. Data on practice parameters and experience levels were also collected. RESULTS Of the 534 survey responses, 279 responded as the "neurosurgeon" and 255 as the "patient." For both vestibular schwannoma and arteriovenous malformation management, more respondents chose resection for their patient but radiosurgery for themselves (p = 0.002 and p = 0.001, respectively). Aneurysm coiling was chosen more often than clipping, but those whose practice was >/= 30% open cerebrovascular neurosurgery were less likely to choose coiling. Overall, neurosurgeons who focus predominantly on tumors were more aggressive in managing the glioma, vestibular schwannoma, arteriovenous malformation, and trauma. Neurosurgeons more than 10 years out of residency were less likely to recommend surgery for management of spinal pain, aneurysm, arteriovenous malformation, and trauma scenarios. CONCLUSIONS In the majority of cases, altering the role of the surgeon did not change the decision to pursue treatment. In certain clinical scenarios, however, neurosurgeons chose treatment options for themselves that were different from what they would have chosen for (or recommended to) their patients. For the management of vestibular schwannomas, arteriovenous malformations, intracranial aneurysms, and hypertensive hemorrhages, responses favored less invasive interventions when the surgeon was the patient. These findings are likely a result of cognitive biases, previous training, experience, areas of expertise, and personal values.