Link, Michael J.

Abstract Introduction Neurenteric cysts (NECs) are rare, congenital lesions lined by endodermal cell-derived columnar or cuboidal epithelium. Based on previous studies, gross total removal of the capsule has been presumed to be the ideal surgical goal. Objective This series was undertaken to further understand the risk of recurrence based on the extent of capsule resection. Methods Records were retrospectively reviewed for all patients with radiographic or pathological evidence of intracranial NEC from 1996 to 2021. Results A total of eight patients were identified; four of eight (50%) presented with headache, and four had signs of one or more cranial nerve syndromes. One patient (13%) presented with third nerve palsy, one (13%) had sixth nerve palsy, and two (25%) with hemifacial spasm. One patient (13%) presented with signs of obstructive hydrocephalus. Magnetic resonance imaging demonstrated T2 hyper- or isointense lesions. Diffusion-weighted imaging was negative in all patients (100%) and T1 contrast-enhanced imaging demonstrated minimal rim enhancement in two patients (25%). In three of eight (38%), a gross total resection (GTR) was achieved, while in four (50%), a near-total resection, and in one (13%), a decompression was performed. Recurrences occurred in two (25%) patients, one with decompression and another with near-total resection, among these 1/2 required repeat surgery after a mean follow-up of 77 months. Conclusion In this series, none from GTR group demonstrated recurrence, while 40% of those receiving less than GTR recurred, underpinning the importance of maximally safe resection in these patients. Overall patients did well without major morbidity from surgery.

Abstract Introduction Skull base neuroanatomy is classically taught using surgical atlases. Although these texts are critical and rich resources for learning three-dimensional (3D) relationships between key structures, we believe they could be optimized and complemented with step-by-step anatomical dissections to fully meet the learning needs of trainees. Methods Six sides of three formalin-fixed latex-injected specimens were dissected under microscopic magnification. A far lateral craniotomy was performed by each of three neurosurgery resident/fellow at varying stages of training. The study objective was the completion and photodocumentation of the craniotomy to accompany a stepwise description of the exposure to provide a comprehensive, intelligible, and anatomically oriented resource for trainees at any level. Illustrative case examples were prepared to supplement approach dissections. Results The far lateral approach provides a wide and versatile corridor for posterior fossa operation, with access spanning the entire cerebellopontine angle (CPA), foramen magnum, and upper cervical region. Key Steps Include The study includes the following steps: positioning and skin incision, myocutaneous flap, placement of burr holes and sigmoid trough, fashioning of the craniotomy bone flap, bilateral C1 laminectomy, occipital condyle/jugular tubercle drilling, and dural opening. Conclusion Although more cumbersome than the retrosigmoid approach, a far lateral craniotomy offers unparalleled access to lesions centered lower or more medially in the CPA, as well as those with significant extension into the clival or foramen magnum regions. Dissection-based neuroanatomic guides to operative approaches provide a unique and rich resource for trainees to comprehend, prepare for, practice, and perform complex cranial operations, such as the far lateral craniotomy.

Abstract Introduction Ki-67 is often used as a proliferation index to evaluate how aggressive a tumor is and its likelihood of recurrence. Vestibular schwannomas (VS) are a unique benign pathology that lends itself well to evaluation with Ki-67 as a potential marker for disease recurrence or progression following surgical resection. Methods All English language studies of VSs and Ki-67 indices were screened. Studies were considered eligible for inclusion if they reported series of VSs undergoing primary resection without prior irradiation, with outcomes including both recurrence/progression and Ki-67 for individual patients. For published studies reporting pooled Ki-67 index data without detailed by-patient values, we contacted the authors to request data sharing for the current meta-analysis. Studies reporting a relationship between Ki-67 index and clinical outcomes in VS for which detailed patients' outcomes or Ki-67 indices could not be obtained were incorporated into the descriptive analysis, but excluded from the formal (i.e., quantitative) meta-analysis. Results A systematic review identified 104 candidate citations of which 12 met inclusion criteria. Six of these studies had accessible patient-specific data. Individual patient data were collected from these studies for calculation of discrete study effect sizes, pooling via random-effects modeling with restricted maximum likelihood, and meta-analysis. The standardized mean difference in Ki-67 indices between those with and without recurrence was calculated as 0.79% (95% confidence interval [CI]: 0.28–1.30; p = 0.0026). Conclusion Ki-67 index may be higher in VSs that demonstrate recurrence/progression following surgical resection. This may represent a promising means of evaluating tumor recurrence and potential need for early adjuvant therapy for VSs.