Stereotactic and Functional Neurosurgery Convection-Enhanced Delivery of Autologous Cerebrospinal Fluid Enhances Basal Ganglia Visualization during MRI-Guided Deep Brain Stimulation Surgery.

INTRODUCTION: The aim of this study was to determine the safety and feasibility of convection-enhanced delivery of autologous cerebrospinal fluid (CSF) for enhancing intraoperative magnetic resonance imaging (MRI) of the basal ganglia during stereotactic neurosurgery. METHODS: This pilot study was conducted in 4 patients with Parkinson's disease (PD) who underwent MRI-guided deep brain stimulation of the globus pallidus internus (GPi). CSF was obtained via lumbar puncture after general anesthesia and prior to incision. A frameless stereotaxy system was installed, and an infusion catheter was inserted to the GPi using intraoperative MRI. Infusion of autologous CSF was performed at a convective rate of 5 µL/min with a maximum volume of infusion (Vi) of 500 mL. T2-weighted MRI scans were obtained every 15 min up to a maximum of 105 min in order to calculate the volume of distribution (Vd). Safety was assessed with adverse event monitoring, and clinical outcomes were measured with changes in unmedicated UPDRS part III and PDQ-39 scores from baseline to 6 months postoperatively. RESULTS: All four infusions were safe and without adverse events. The mean unmedicated UPDRS part III and PDQ-39 scores improved by 24% and 26%, respectively. The Vd:Vi ratio ranged from 2.2 to 2.8 and peaked 45 min from the onset of infusion, which is when the borders of the GPi could generally be visualized based on T2-weighted MRI. Two patients underwent refinement of the stereotactic targeting based on infusion-enhanced images. CONCLUSIONS: The convective administration of autologous CSF to deep brain structures appears safe and feasible for enhancing intraoperative MRI during stereotactic procedures. Infusion-enhanced imaging with target-specific infusates could be developed to visualize neurochemical circuits or cellular regions that currently are not seen with anatomic/structural MRI.

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

OBJECTIVE: Primary spinal cord astrocytomas are rare, fatal, and poorly studied. METHODS: This study included a 2-center, retrospective analysis of primary spinal cord astrocytoma patients from 1997 to 2020. Patients with drop metastases or without at least one follow-up were excluded. RESULTS: Seven World Health Organization grade I, 6 grade II, 7 grade III, and 4 grade IV astrocytoma patients were included. Older patients had higher grades (median 20 years in grade I vs. 36.5 in grade IV). The median follow-up was 15 months. Thirteen patients were discharged to rehabilitation. Eight patients demonstrated radiographic progression. Adjuvant therapy was utilized more in higher grades (5 of 13 grades III vs. all 11 grades IIIIV). Six patients died (1 death in grades III vs. 5 in grades IIIIV). Ten patients had worsened symptoms at the last follow-up. The median progression-free survival in grade I, II, III, and IV tumors was 116, 36, 8, and 8.5 months, respectively. The median overall survival in grade I, II, III, and IV tumors was 142, 69, 19, and 12 months, respectively. Thrombotic complications occurred in 2 patients, one with isocitrate dehydrogenasewild type glioblastoma. CONCLUSIONS: Outcomes worsen with higher grades and lead to difficult postoperative periods. Clinicians should be vigilant for thromboembolic complications. Further research is needed to understand these rare tumors.

The landscape of brain tumor mimics in neuro-oncology practice.

BACKGROUND AND OBJECTIVE: Differentiating neoplastic and non-neoplastic brain lesions is essential to make management recommendations and convey prognosis, but the distinction between brain tumors and their mimics in practice may prove challenging. The aim of this study is to provide the incidence of brain tumor mimics in the neuro-oncology setting and describe this patient subset. METHODS: Retrospective study of adult patients referred to the Division of Neuro-oncology for a presumed diagnosis of brain tumor from January 1, 2005 through December 31, 2017, who later satisfied the diagnosis of a non-neoplastic entity based on neuroimaging, clinical course, and/or histopathology evaluation. We classified tumor mimic entities according to clinical, radiologic, and laboratory characteristics that correlated with the diagnosis. RESULTS: The incidence of brain tumor mimics was 3.4% (132/3897). The etiologies of the non-neoplastic entities were vascular (35%), inflammatory non-demyelinating (26%), demyelinating (15%), cysts (10%), infectious (9%), and miscellaneous (5%). In our study, 38% of patients underwent biopsy to determine diagnosis, but in 26%, the biopsy was inconclusive. DISCUSSION: Brain tumor mimics represent a small but important subset of the neuro-oncology referrals. Vascular, inflammatory, and demyelinating etiologies represent two-thirds of cases. Recognizing the clinical, radiologic and laboratory characteristics of such entities may improve resource utilization and prevent unnecessary as well as potentially harmful diagnostic and therapeutic interventions.

Hemangioblastoma diagnosis and surveillance in von Hippel-Lindau disease: a consensus statement.

OBJECTIVE: Hemangioblastomas are a frequent underlying cause of neurological morbidity and death in patients with von Hippel-Lindau disease (VHL). Although these benign tumors can cause significant neurological debility when undetected and untreated, unified evidence-based surveillance recommendations for VHL patients have not been established. To develop consensus recommendations, the VHL Alliance established an expert committee, named the International VHL Surveillance Guidelines Consortium, to define surveillance recommendations. METHODS: The Central Nervous System (CNS) Hemangioblastoma Subcommittee of the Guidelines Consortium was formed as a multidisciplinary team of experts in the diagnosis and management of hemangioblastomas. Recommendations were formulated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) and National Comprehensive Cancer Network Categories of Evidence and Consensus categorization after a comprehensive literature review. RESULTS: Published studies (n = 49) that discussed age at onset, MRI frequency, natural history of VHL, and the risks and benefits of surveillance were analyzed. Based on this analysis, the authors recommend that clinical evaluation (yearly) be used as the primary screening tool for hemangioblastomas in VHL. The subcommittee suggests that screening be performed between the ages of 11 and 65 years, or with the onset of symptoms, for synchronicity with other testing regimens in VHL. The subcommittee also recommends that baseline MRI be first performed at the age of 11 years (suggested 2B, level of evidence D) or after identification of neurological symptoms or signs (if earlier) and continue every 2 years (recommended 2A, level of evidence A). CONCLUSIONS: The CNS Hemangioblastoma Subcommittee of the International VHL Surveillance Guidelines Consortium here proposes guidelines that aim to increase the early detection of VHL-associated hemangioblastomas to reduce their morbidity and mortality.

Melanoma brain metastasis mimicking cortical laminar necrosis.

Background: Metastatic lesions to the brain are common in patients with melanoma. Imaging characteristics can support the diagnosis of metastatic melanoma, but alternative diagnoses should be considered. Case Description: Here, we present a case of a 57-year-old man in whom a metastatic melanoma initially mimicked the imaging characteristics of cortical laminar necrosis. Conclusion: This comprises the first report of melanoma brain metastasis presenting with these imaging characteristics and emphasizes the importance of maintaining a high index of suspicion for metastatic lesions in patients with known cancer.

Bevacizumab as a surgery-sparing agent for spinal ependymoma in patients with neurofibromatosis type II: Systematic review and case.

Neurofibromatosis type 2 (NF2) is a rare, hereditary tumor syndrome, often requiring repeated surgeries for multiple lesions with significant cumulative morbidity. As such, non-operative management should be considered when possible for this patient population. The aim of this study is to provide a systematic review of the literature regarding this treatment strategy. A descriptive case of a patient in whom bevacizumab treatments enabled over 15 years of surgical postponement for a symptomatic spinal cord ependymoma is also provided. Evidence suggests that bevacizumab is a reasonable surgery-deferring option for cystic lesions, and it may be especially useful in NF2 patients to reduce cumulative morbidity.

Comparative clinical and genomic analysis of neurofibromatosis type 2-associated cranial and spinal meningiomas.

Neurofibromatosis type 2 (NF2) is an autosomal dominant Mendelian tumor predisposition disorder caused by germline pathogenic variants in the tumor suppressor NF2. Meningiomas are the second most common neoplasm in NF2, often occurring in multiple intracranial and spinal locations within the same patient. In this prospective longitudinal study, we assessed volumes and growth rates of ten spinal and ten cranial benign meningiomas in seven NF2 patients that concluded with surgical resection and performed whole-exome sequencing and copy-number variant (CNV) analysis of the tumors. Our comparison of the volume and the growth rate of NF2-associated spinal and cranial meningiomas point to the differences in timing of tumor initiation and/or to the differences in tumor progression (e.g., non-linear, saltatory growth) at these two anatomical locations. Genomic investigation of these tumors revealed that somatic inactivation of NF2 is the principal and perhaps the only driver of tumor initiation; and that tumor progression likely occurs via accumulation of CNVs, rather than point mutations. Results of this study contribute to a better understanding of NF2-associated meningiomas clinical behavior and their genetic underpinnings.

Variable response of CNS hemangioblastomas to Pazopanib in a single patient with von Hippel-Lindau disease: Case report.

Von Hippel-Lindau (VHL) disease is a multisystem genetic disease, the cardinal manifestations of which include central nervous system hemangioblastomas (CNS HB), renal cell carcinomas (RCC), and pheochromocytoma. Tumorigenesis in VHL of both RCC and CNS HB occurs secondary to downstream effects of a mutated or absent VHL protein. Treatment of RCCs with tyrosine kinase inhibitors (TKIs) such as Pazopanib is now first line therapy, but their effect on VHL-associated CNS HBs remains unknown. We report the use of Pazopanib in a patient with VHL disease for treatment of RCC who also harbored multiple CNS HBs. Following initiation of treatment, a large cervical and a lumbar spinal HB regressed in size while the remaining CNS HBs exhibited stable or progressive disease. These findings highlight the multiplicity of factors contributing to hemangioblastoma development, even among tumors with a common germline mutation, and the potential limitations of TKIs, but additionally this report supports the conservative management of asymptomatic VHL patients with spinal HBs whereby tumor response to TKI treatment may alleviate or postpone the need for surgery.

Audiologic Natural History of Small Volume Cochleovestibular Schwannomas in Neurofibromatosis Type 2.

OBJECTIVE: To characterize the audiometric natural progression in patient-ears with small volume (<1,000 mm), treatment-naïve cochleovestibular schwannomas (CVSs) in Neurofibromatosis Type 2 (NF2). STUDY DESIGN: Prospective, longitudinal cohort study. SETTING: Quaternary medical research institute. PATIENTS: One hundred eleven ears in 71 NF2 patients with small, treatment-naïve CVSs observed from July 2006 to July 2016. INTERVENTION: Serial audiometric testing, including pure tone audiometry, speech audiometry, and magnetic resonance imaging (MRI). OUTCOME MEASURES: Four-frequency pure tone average (4f-PTA) of 0.5, 1, 2, and 4 kHz and word recognition score (WRS) were recorded. Their changes were compared with MRI changes in CVS volume over time. Times to significant hearing loss (10 dB loss in 4f-PTA) and WRS based on 95% critical difference were measured. RESULTS: Linear regression analysis showed a significant correlation with baseline hearing level (4f-PTA) and internal auditory canal (IAC) tumor volume to annual hearing decrease rate (AHDR) (p = 0.003, p = 0.0004). Hearing level at baseline and tumor volume correlate with AHDR while tumor volume growth rate does not. Two-way analysis of variance found significant differences in AHDR, risk of significant hearing loss, and risk of critical difference in WRS based on baseline hearing level (abnormal or normal) and IAC tumor volume (greater or less than 200 mm). CONCLUSION: Subjects with normal baseline hearing and small IAC tumor component had a low AHDR and low risk of significant hearing loss and may warrant conservative management while the presence of baseline hearing loss and large IAC volume resulted in higher ADHR and greater risk for further hearing loss and may benefit from early treatment interventions.

Case Report: Facial Nerve Bifurcation Noted During Resection of Vestibular Schwannoma.

BACKGROUND AND IMPORTANCE: Resection of cerebellopontine angle tumors is challenging because the proximity of the facial nerve puts it at risk of inadvertent injury and subsequent dysfunction. It is critical to consider variations in anatomy and be aware of the potential deviations in the course of the nerve in order to avoid damage. CLINICAL PRESENTATION: We present a case of a facial nerve bifurcation identified during resection of a vestibular schwannoma. CONCLUSION: This is the only reported case of proximal facial nerve bifurcation. We review what is known about variations in proximal facial nerve anatomy, the rates of facial nerve injury after schwannoma resection, and the importance of neuromonitoring in identifying the nerve and predicting function postoperatively. Ultimately, understanding possible anatomic variations in the nerve is critical to minimize iatrogenic injury during surgery.

First insight into the somatic mutation burden of neurofibromatosis type 2-associated grade I and grade II meningiomas: a case report comprehensive genomic study of two cranial meningiomas with vastly different clinical presentation.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a rare autosomal dominant nervous system tumor predisposition disorder caused by constitutive inactivation of one of the two copies of NF2. Meningiomas affect about one half of NF2 patients, and are associated with a higher disease burden. Currently, the somatic mutation landscape in NF2-associated meningiomas remains largely unexamined. CASE PRESENTATION: Here, we present an in-depth genomic study of benign and atypical meningiomas, both from a single NF2 patient. While the grade I tumor was asymptomatic, the grade II tumor exhibited an unusually high growth rate: expanding to 335 times its initial volume within one year. The genomes of both tumors were examined by whole-exome sequencing (WES) complemented with spectral karyotyping (SKY) and SNP-array copy-number analyses. To better understand the clonal composition of the atypical meningioma, the tumor was divided in four sections and each section was investigated independently. Both tumors had second copy inactivation of NF2, confirming the central role of the gene in meningioma formation. The genome of the benign tumor closely resembled that of a normal diploid cell and had only one other deleterious mutation (EPHB3). In contrast, the chromosomal architecture of the grade II tumor was highly re-arranged, yet uniform among all analyzed fragments, implying that this large and fast growing tumor was composed of relatively few clones. Besides multiple gains and losses, the grade II meningioma harbored numerous chromosomal translocations. WES analysis of the atypical tumor identified deleterious mutations in two genes: ADAMTSL3 and CAPN5 in all fragments, indicating that the mutations were present in the cell undergoing fast clonal expansion CONCLUSIONS: This is the first WES study of NF2-associated meningiomas. Besides second NF2 copy inactivation, we found low somatic burden in both tumors and high level of genomic instability in the atypical meningioma. Genomic instability resulting in altered gene dosage and compromised structural integrity of multiple genes may be the primary reason of the high growth rate for the grade II tumor. Further study of ADAMTSL3 and CAPN5 may lead to elucidation of their molecular implications in meningioma pathogenesis.

Geographically Remote Cerebral Venous Sinus Thrombosis in Patients with Intracranial Tumors.

Cerebral venous sinus thrombosis (CVST) related to intracranial tumors has most commonly been recognized as an operative complication related to local operative factors such as retraction or direct venous injury. CVST may also be caused by tumor-related factors such as local mass effect but rarely occurs geographically remote from the site of the tumor. We report 6 cases treated at our institution of intracranial supratentorial tumors associated with CVST. In each case, the CVST was remote from the surgical site. In 3 cases CVST was noted at the time of resection, and 3 cases occurred in a delayed fashion. Each case is discussed in detail, and the utility of intraoperative magnetic resonance imaging in the early diagnosis of this complication is highlighted.

Redefining the Prevalence of Dural Involvement in Rosai-Dorfman Disease of the Central Nervous System.

BACKGROUND: Sinus histiocytosis with massive lymphadenopathy, also known as Rosai-Dorfman disease, is a rare condition, classically characterized by painless, massive cervical lymphadenopathy. Histologically, the pathognomonic findings include a dense, mixed inflammatory infiltrate with areas of emperipolesis. Albeit infrequent, when Rosai-Dorfman disease affects the central nervous system, it typically manifests as an isolated dural lesion, often mimicking a meningioma. A purely intraparenchymal manifestation of Rosai-Dorfman disease of the brain and spine with absent dural involvement is exceedingly rare. CASE DESCRIPTION: In this report, we describe a 59-year-old woman who underwent surgical excision of an intraparenchymal cerebellar lesion. Histologic analysis of the resected specimen diagnosed isolated Rosai-Dorfman disease with absent systemic involvement. We also provide an updated review of the literature of nondural-based Rosai-Dorfman disease in the central nervous system. CONCLUSIONS: With the recent increase of such reported cases, it becomes imperative that Rosai-Dorfman be considered more than as a dural lesion that may mimic meningioma. Diagnostic and therapeutic challenges surrounding this disease entity are also discussed.

Tumors displaying hybrid schwannoma and neurofibroma features in patients with neurofibromatosis type 2.

Although schwannoma and neurofibroma tumors are generally reported as distinct pathologic diagnoses, sporadic schwannoma/neurofibroma hybrid nerve sheath tumors have been reported in the general population with components of both entities. We report the clinicopathological features of these hybrid nerve sheath tumors in patients with neurofibromatosis type 2 (NF2). A retrospective review of nerve sheath tumor surgical specimens from patients with NF2 enrolled at the National Institutes of Health was performed. Those specimens reported to have schwannoma-like and neurofibromalike features were selected for further characterization by morphology, immunohistochemical panel (CD34, S100, neurofilament triplet protein (immunostain) (NFTP), epithelial membrane antigen (EMA)), and confirmation as hybrid tumors. Of 43 total NF2 patients undergoing resection of nerve sheath tumors, 11 specimens from 11 (26%) patients were found to be benign nerve sheath tumors exhibiting hybrid features of both neurofibroma and schwannoma. Immunohistochemical studies showed the schwannoma component to be S100+, CD 34- while the neurofibroma component was CD34+, variable S100+. Our experience emphasizes the importance of including this distinct tumor subtype, the schwannoma/neurofibroma hybrid tumor, in the differential diagnosis of nerve sheath tumors in NF2 patients and suggests that the relationship between neurofibroma and schwannoma tumors is closer than previously suspected..

Evidence of polyclonality in neurofibromatosis type 2-associated multilobulated vestibular schwannomas.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a tumor syndrome that results from mutation of the NF2 tumor suppressor gene. The hallmark of NF2 is the presence of bilateral vestibular schwannoma (VS). Though NF2-associated and sporadic VS share identical histopathologic findings and cytogenetic alterations, NF2-associated VS often appears multilobulated, is less responsive to radiosurgery, and has worse surgical outcomes. Temporal bone autopsy specimens and MRI of the inner ear performed on NF2 patients suggest that multiple discrete tumors may be present within the labyrinth and cerebellopontine angle. METHODS: Treatment-naïve ears in patients enrolled in a prospective NF2 natural history study (NIH#08-N-0044) were included for MRI analysis. T2-weighted and postcontrast T1-weighted MRIs were evaluated for the presence of multiple discrete tumors or a multilobulated mass. Peripheral blood (germline) and regional samples of tumor tissue were procured from consecutive patients enrolled in this study undergoing resection of a multilobulated VS (MVS). Histopathologic evaluation and genetic analysis (single nucleotide polymorphism array analysis, NF2 sequencing) were performed on each specimen. RESULTS: Over half of NF2 ears harbored either an MVS (60/139 ears) or multiple discrete masses (19/139 ears). For 4 successive MVSs, genetic analysis revealed an admixture of cell populations, each with its own somatic NF2 mutation or deletion. CONCLUSIONS: These findings suggest that the majority of NF2-associated VSs are polyclonal, such that the tumor mass represents a collision of multiple, distinct tumor clones. This explains the characteristic lobulated gross appearance of NF2-associated VS, and may also explain the substantially different treatment outcomes compared with sporadic VS.

Audiovestibular Characteristics of Small Cochleovestibular Schwannomas in Neurofibromatosis Type 2.

OBJECTIVE: Describe the relationship between cochleovestibular schwannoma (CVS) volume, audiovestibular characteristics, and magnetic resonance imaging (MRI) findings in patients with neurofibromatosis type 2 (NF2). STUDY DESIGN: Subgroup analysis of NF2 prospective natural history study from 2008 to 2011. SETTING: Quaternary medical research institute. SUBJECTS AND METHODS: NF2 patients with small treatment-naive CVSs (volume <1000 mm(3)) by ear; N = 49 ears (32 patients). Cross-sectional analysis of the following parameters was performed: tumor size, auditory brainstem response (ABR), 4-frequency pure-tone average (4f-PTA; 0.5, 1, 2, and 4KHz), cervical vestibular evoked myogenic potential (cVEMP), caloric testing, 240° velocity step test (VST), and MRI findings. RESULTS: For all physiologic measures but the 4f-PTA, larger tumors correlated with abnormal responses (P < .05). For abnormal ABR, mean tumor volume was 405 vs 151 mm(3) (P = .0007) for normal ABR. Similarly, larger tumors correlated with weak caloric responses (mean 521 vs 165 mm(3); P = .0007) and weak cVEMP (mean 357 vs 192 mm(3); P = .0262). Tumor volume was not significantly correlated with 4f-PTA. Elevated intralabyrinthine protein on MRI fluid-attenuated inversion recovery sequences was correlated with larger tumor volume (mean 333 vs 55 mm(3); P = .001) and abnormal ABR and 4f-PTA (P < .05) but did not correlate with cVEMP, VST, or caloric responses. CONCLUSION: In our cohort, ABR, caloric response, cVEMP, and elevated intralabyrinthine protein correlated with tumor volume, but 4f-PTA did not. Abnormal ABR and 4f-PTA correlated with elevated intralabyrinthine protein. These findings may provide insight on the effect of small CVS on the inner ear and cochleovestibular nerves, which may aid in their optimal management.

Prospective natural history study of central nervous system hemangioblastomas in von Hippel-Lindau disease.

OBJECT: The tumors most frequently associated with von Hippel-Lindau (VHL) disease are hemangioblastomas. While they are associated with significant neurological impairment and mortality, their natural history and optimal management have not been fully defined. METHODS: Patients with VHL were enrolled in a prospective study designed to define the natural history of CNS hemangioblastomas. In the present analysis, serial imaging, laboratory, genetic, and clinical data were evaluated in those with at least 2 years of follow-up data. RESULTS: At study entrance 225 patients (111 males, 114 females) harbored 1921 CNS hemangioblastomas in the supratentorial compartment (21 tumors [1%]), cerebellum (865 [45%]), brainstem (129 [7%]), spinal cord (689 [36%]), cauda equina (212 [11%]), and nerve roots (5 [0.3%]; follow-up 15,819 hemangioblastoma-years). Increased tumor burden was associated with partial deletions in the VHL gene (p = 0.005) and male sex (p = 0.002). Hemangioblastoma development (median 0.3 new tumors/year) was associated with younger age (p < 0.0001) and more tumors at study entrance (p < 0.0001). While 1278 hemangioblastomas (51%) did not grow, 1227 hemangioblastomas (49%) grew in a saltatory (886 [72%]), linear (76 [6%]), or exponential (264 [22%]) pattern. Faster tumor growth was associated with male sex (p = 0.001), symptomatic tumors (p < 0.0001), and tumors associated with cysts (p < 0.0001). Location-dependent tumor size was the primary predictor of eventual symptom formation (159 symptomatic tumors [6.3%]; area under the curve > 0.9). CONCLUSIONS: Central nervous system hemangioblastoma burden in VHL is associated with partial germline deletions and male sex. Unpredictable growth of hemangioblastomas compromises assessment of nonsurgical therapies. The judicious treatment of symptom-producing hemangioblastomas, while avoiding unnecessary treatment of asymptomatic tumors that may not progress, can provide clinical stability.

Intraoperative ultrasound guidance for the placement of permanent ventricular cerebrospinal fluid shunt catheters: a single-center historical cohort study.

OBJECTIVE: Despite the frequency with which ventriculoperitoneal shunts are placed, ventricular catheter revision rates remains as high as 30%-40% at 1 year. Many neurosurgeons place ventricular catheters "blindly" depending on anatomical landmarks and personal experience. To determine whether intraoperative ultrasonography is beneficial for ventricular catheter placement, we performed a historical cohort study comparing shunts placed with intraoperative ultrasound (US) guidance to those placed blindly. METHODS: We reviewed all shunts placed by the Department of Neurosurgery at the University of Virginia from January 2005 to January 2007. During that time 211 patients underwent 242 shunts, with US use determined by surgeon's preference. Ninety-two shunts were placed by the use of US guidance, and 150 were placed without US. Adults received 176 shunts, 56 with US. Children received 66 shunts, 36 with US. Mean follow-up was 21.6 months. The primary end points examined were shunt revision, ventricular catheter revision (VCR), and acute VCR (revision within 1 week for an improperly-placed catheter). RESULTS: The use of US was associated with a statistically significant decrease in shunt revisions (odds ratio 0.492; 95% confidence interval 0.253-0.958). Of the shunts placed with US guidance, 21.7% required revision, compared with 29.3% without US. VCRs and acute VCRs occurred in 9.8% and 2.2%, respectively, for US shunts, compared with 14% and 5.3% without US. Pediatric revision rates were 30.6% with US versus 53.3% without, whereas adult rates were 16.1% and 23.3%, respectively. The benefit of US was more profound for occipital shunts. CONCLUSIONS: The use of US for the placement of permanent cerebrospinal fluid shunt catheters is associated with a decreased risk of shunt revision.

Neurological Surgery Training Abroad as a Progression to the Final Year of Training and Transition to Independent Practice.

BACKGROUND: Residents at the University of Virginia spend 1 year abroad at a neurological surgery program prior to their chief year. The Accreditation Council for Graduate Medical Education (ACGME) considers international rotations elective experiences and does not count them toward clinical accreditation. OBJECTIVE: We compared clinical training obtained in New Zealand (NZ) to data from US ACGME-accredited programs to see if it was reasonable to reconsider the former as clinical training. METHODS: We compared US national average chief case volumes to those performed by University of Virginia residents rotating in NZ over the past 3 years, using case volume comparisons and a survey of the residents' experience. RESULTS: The mean number of cases performed in NZ was above the 50th percentile for US averages for adult cranial cases, including the 70th to 90th percentile for aneurysms and 50th to 70th percentile for tumors. The average number of cases performed in 1 year in NZ satisfied the cranial case quota for 4 of 6 adult and 2 of 3 pediatric areas over the entire residency. The rotation doubled the cranial exposure of graduating residents at the chief level without diluting the experience of residents in the core program. All residents reported being "very satisfied" with the experience, noting it facilitated their transition to chief year and independent practice. CONCLUSIONS: Clinical training obtained during an international rotation in NZ is comparable to that attained in the United States. The international experience in NZ facilitated advancement in all 6 competencies, and should be considered adequate for clinical neurological surgery education.