neuroGPT-X: toward a clinic-ready large language model.

OBJECTIVE: The objective was to assess the performance of a context-enriched large language model (LLM) compared with international neurosurgical experts on questions related to the management of vestibular schwannoma. Furthermore, another objective was to develop a chat-based platform incorporating in-text citations, references, and memory to enable accurate, relevant, and reliable information in real time. METHODS: The analysis involved 1) creating a data set through web scraping, 2) developing a chat-based platform called neuroGPT-X, 3) enlisting 8 expert neurosurgeons across international centers to independently create questions (n = 1) and to answer (n = 4) and evaluate responses (n = 3) while blinded, and 4) analyzing the evaluation results on the management of vestibular schwannoma. In the blinded phase, all answers were assessed for accuracy, coherence, relevance, thoroughness, speed, and overall rating. All experts were unblinded and provided their thoughts on the utility and limitations of the tool. In the unblinded phase, all neurosurgeons provided answers to a Likert scale survey and long-answer questions regarding the clinical utility, likelihood of use, and limitations of the tool. The tool was then evaluated on the basis of a set of 103 consensus statements on vestibular schwannoma care from the 8th Quadrennial International Conference on Vestibular Schwannoma. RESULTS: Responses from the naive and context-enriched Generative Pretrained Transformer (GPT) models were consistently rated not significantly different in terms of accuracy, coherence, relevance, thoroughness, and overall performance, and they were often rated significantly higher than expert responses. Both the naive and content-enriched GPT models provided faster responses to the standardized question set than expert neurosurgeon respondents (p < 0.01). The context-enriched GPT model agreed with 98 of the 103 (95%) consensus statements. Of interest, all expert surgeons expressed concerns about the reliability of GPT in accurately addressing the nuances and controversies surrounding the management of vestibular schwannoma. Furthermore, the authors developed neuroGPT-X, a chat-based platform designed to provide point-of-care clinical support and mitigate the limitations of human memory. neuroGPT-X incorporates features such as in-text citations and references to enable accurate, relevant, and reliable information in real time. CONCLUSIONS: The present study, with its subspecialist-level performance in generating written responses to complex neurosurgical problems for which evidence-based consensus for management is lacking, suggests that context-enriched LLMs show promise as a point-of-care medical resource. The authors anticipate that this work will be a springboard for expansion into more medical specialties, incorporating evidence-based clinical information and developing expert-level dialogue surrounding LLMs in healthcare.

Vertebral Artery Mobilization During Transcondylar Extreme Far Lateral Approach for Excision of Large Foramen Magnum Meningioma: 2-Dimensional Operative Video.

Foramen magnum meningiomas are challenging lesions owing to their proximity to the lower brainstem, vertebrobasilar system, and lower cranial nerves.1,2 Tumor size, origin, morphology, relationship to neurovascular structures, and bony anatomy determine the optimal surgical approach.2,3 Classically, far lateral approaches have been the workhorse approach to the foramen magnum. Variations of the far lateral including transcondylar and extended transcondylar (paracondylar), with or without transposition of the vertebral artery, are sometimes used for a more lateral approach to the brainstem and clivus. Here, we present a 60-year-old male patient presenting with a large foramen magnum meningioma. Preoperative workup includes computed tomography and MRI with angiography to assess for posterior circulation dominance, anatomic variants including posterior inferior cerebellar artery origin, venous, and bony anatomy.1,4 An extreme far lateral provides access anterior to the vertebral artery to extend exposure beyond the standard far lateral approach. This comprised transcondylar drilling, bony mobilization of the V3 Vertebral artery from C1 foramen transversarium, and dural mobilization of vertebral artery with a dural cuff at its site of dural entry. The patient tolerated the procedure, gross total resection was achieved, and the patient was discharged home. This video demonstrates in detail the steps of exposure, condylar drilling, vertebral artery transposition, and dural opening. These maneuvers can be difficult to conceptualize yet are key to successful extended transcondylar exposure. The patient gave informed consent for surgery and video recording. Institutional Review Board approval was deemed unnecessary.

Emotional Lability as a Symptom of Extra-axial Posterior Fossa Tumors: a Case-Control Review of Neuroanatomy and Patient-Reported Quality of Life.

Introduction Emotional lability (EL), the uncontrollable and unmotivated expression of emotion, is a rare and distressing symptom of brainstem compression. In published case reports, EL from an extra-axial posterior fossa tumor was alleviated by tumor resection. The primary aim herein was to radiographically establish the degree of compression from mass lesions onto brainstem structures. Secondarily, we compared changes in patient-reported quality of life (QOL) pre- and postoperatively. Methods A retrospective review of posterior fossa tumors treated between 2002 and 2018 at Vancouver General Hospital revealed 11 patients with confirmed EL. Each case was matched to three controls. A lateral brainstem compression scale characterized mass effect at the level of the medulla, pons, and midbrain in preoperative axial T2-weighted fluid-attenuated inversion recovery magnetic resonance imaging (FLAIR MRI) scans. Compression and clinical variables were compared between patient groups. Short Form-36 version 1 health surveys were retrospectively obtained from patient charts to compare pre- versus postoperative changes in survey scores between EL and control patients. Results EL symptoms ceased postoperatively for all EL patients. EL tumors exert greater compression onto the pons ( p = 0.03) and EL patients more commonly have cerebellar findings preoperatively ( p = 0.003). Patients with EL-causing tumors experienced greater improvement postoperatively in "Health Change" ( p = 0.05), which was maintained over time. Conclusion Findings suggest that compression onto the pons inhibits control over involuntary, stereotyped expression of emotion. This adds to evidence that EL may be attributed to cerebellum deafferentation from cortical and limbic structures through the basis pontis, leading to impaired modulation of emotional response. QOL results augment benefits of offering patients EL-alleviating tumor resection surgery.

International Tuberculum Sellae Meningioma Study: Preoperative Grading Scale to Predict Outcomes and Propensity-Matched Outcomes by Endonasal Versus Transcranial Approach.

BACKGROUND AND OBJECTIVES: Tuberculum sellae meningiomas are resected via an expanded endonasal (EEA) or transcranial approach (TCA). Which approach provides superior outcomes is debated. The Magill-McDermott (M-M) grading scale evaluating tumor size, optic canal invasion, and arterial involvement remains to be validated for outcome prediction. The objective of this study was to validate the M-M scale for predicting visual outcome, extent of resection (EOR), and recurrence, and to use propensity matching by M-M scale to determine whether visual outcome, EOR, or recurrence differ between EEA and TCA. METHODS: Forty-site retrospective study of 947 patients undergoing tuberculum sellae meningiomas resection. Standard statistical methods and propensity matching were used. RESULTS: The M-M scale predicted visual worsening (odds ratio [OR]/point: 1.22, 95% CI: 1.02-1.46, P = .0271) and gross total resection (GTR) (OR/point: 0.71, 95% CI: 0.62-0.81, P < .0001), but not recurrence ( P = .4695). The scale was simplified and validated in an independent cohort for predicting visual worsening (OR/point: 2.34, 95% CI: 1.33-4.14, P = .0032) and GTR (OR/point: 0.73, 95% CI: 0.57-0.93, P = .0127), but not recurrence ( P = .2572). In propensity-matched samples, there was no difference in visual worsening ( P = .8757) or recurrence ( P = .5678) between TCA and EEA, but GTR was more likely with TCA (OR: 1.49, 95% CI: 1.02-2.18, P = .0409). Matched patients with preoperative visual deficits who had an EEA were more likely to have visual improvement than those undergoing TCA (72.9% vs 58.4%, P = .0010) with equal rates of visual worsening (EEA 8.0% vs TCA 8.6%, P = .8018). CONCLUSION: The refined M-M scale predicts visual worsening and EOR preoperatively. Preoperative visual deficits are more likely to improve after EEA; however, individual tumor features must be considered during nuanced approach selection by experienced neurosurgeons.

International Tuberculum Sellae Meningioma Study: Surgical Outcomes and Management Trends.

BACKGROUND AND OBJECTIVES: Tuberculum sellae meningiomas (TSMs) can be resected through transcranial (TCA) or expanded endonasal approach (EEA). The objective of this study was to report TSM management trends and outcomes in a large multicenter cohort. METHODS: This is a 40-site retrospective study using standard statistical methods. RESULTS: In 947 cases, TCA was used 66.4% and EEA 33.6%. The median maximum diameter was 2.5 cm for TCA and 2.1 cm for EEA ( P < .0001). The median follow-up was 26 months. Gross total resection (GTR) was achieved in 70.2% and did not differ between EEA and TCA ( P = .5395). Vision was the same or better in 87.5%. Vision improved in 73.0% of EEA patients with preoperative visual deficits compared with 57.1% of TCA patients ( P < .0001). On multivariate analysis, a TCA (odds ratio [OR] 1.78, P = .0258) was associated with vision worsening, while GTR was protective (OR 0.37, P < .0001). GTR decreased with increased diameter (OR: 0.80 per cm, P = .0036) and preoperative visual deficits (OR 0.56, P = .0075). Mortality was 0.5%. Complications occurred in 23.9%. New unilateral or bilateral blindness occurred in 3.3% and 0.4%, respectively. The cerebrospinal fluid leak rate was 17.3% for EEA and 2.2% for TCA (OR 9.1, P < .0001). The recurrence rate was 10.9% (n = 103). Longer follow-up (OR 1.01 per month, P < .0001), World Health Organization II/III (OR 2.20, P = .0262), and GTR (OR: 0.33, P < .0001) were associated with recurrence. The recurrence rate after GTR was lower after EEA compared with TCA (OR 0.33, P = .0027). CONCLUSION: EEA for appropriately selected TSM may lead to better visual outcomes and decreased recurrence rates after GTR, but cerebrospinal fluid leak rates are high, and longer follow-up is needed. Tumors were smaller in the EEA group, and follow-up was shorter, reflecting selection, and observation bias. Nevertheless, EEA may be superior to TCA for appropriately selected TSM.

Correlation of Pituitary Descent and Diabetes Insipidus After Transsphenoidal Pituitary Macroadenoma Resection.

BACKGROUND: Endoscopic transsphenoidal surgery remains the technique of choice for resection of pituitary adenoma. Postoperative diabetes insipidus (DI) is most often transient and observed in 1.6% to 34% of patients, whereas permanent DI has been reported in 0% to 2.7% of patients. The proposed mechanism was the transduction of traction forces exerted by the surgeon on the descended diaphragma sellae and through the pituitary stalk. OBJECTIVE: To quantify and correlate the degree of pituitary gland descent with postoperative DI. METHODS: Of 374 patients who underwent transsphenoidal resection of a pituitary adenoma between 2010 and 2020 at our institution, we report a cohort of 30 patients (Group A) DI. We also report a matched cohort by tumor volume of 30 patients who did not develop DI (Group B). We quantified the tension on the pituitary stalk by calculating pituitary descent interval (PDI) by comparing preoperative and postoperative position of the pituitary gland and using Pythagoras' formula where , with craniocaudal (CC) and anterior-posterior (AP) representing measurements of pituitary translation in respective directions after resection. RESULTS: Patients who developed DI had significantly greater pituitary gland translations in the craniocaudal (23.0 vs 16.3 mm, P = .0015) and anteroposterior (2.4 vs 1.5 mm, P = .0168) directions. Furthermore, Group A had a statistically greater PDI, which was associated with development of DI (23.2 vs 16.6 mm, P = .0017). CONCLUSION: We were able to quantify pituitary descent and subsequent tension on the pituitary stalk, while also associating it with development of postoperative DI after pituitary adenoma resection.

The Unified Visual Function Scale Assessments Show Inter- and Intraobserver Agreement and Correlate with Patient Quality of Life in Skull Base Parasellar Tumors.

Introduction The authors have previously described the Unified Visual Function Scale (UVFS). Here, we assessed intra- and interobserver reliability of the scale, and investigated correlations with patient quality of life (QoL). Methods Eight healthcare practitioners independently applied the UVFS in 20 representative cases from our parasellar meningioma series. Scoring was compared with consensus grades assigned by lead authors. Inter- and intraobserver agreement was measured using intraclass correlation coefficient (ICC), Fleiss's κ, and Cohen's κ, respectively. Patient QoL was assessed Visual Function Questionnaire 25 (VFQ-25) or Activities of Daily Vision Scale (ADVS), and correlated with UVFS grades for each eye. Results The interobserver ICC was 0.734 (95% confidence interval [CI]: 0.652-0.811), with Fleiss's κ of 0.758, 0.691, and 0.899 for grades A, B, and C, respectively. The intraobserver ICC was 0.758 (95% CI: 0.638-0.872), and Fleiss's κ was 0.604, 0.268, and 0.910 for grades A, B, and C respectively. The Cohen's κ for agreement between UVFS category grades and consensus grades was 0.816 (95 CI: 0.698-0.934). Survey response rate was 51% (27/53). The UVFS demonstrated strong correlation with VFQ-25 subdivisions general vision ( r = 0.7712), near activities ( r = 0.7262), peripheral vision ( r = 0.6722), and driving ( r = 0.6608), and also demonstrated strong correlation with the overall ADVS score ( r = 0.5902). Conclusion This study shows that the UVFS is valid within a small subset of observers, and accurately reflects patient QoL. It is robust and practical, which make it suitable for broad implementation.

Large Subependymoma Inferior to the Cerebellopontine Angle With Significant Obstructive Hydrocephalus: A Case Report on an Extremely Rare Tumor.

Subependymomas are rare yet benign tumors that are commonly found within the ventricular system. We describe the case of a 51-year-old male presenting with hydrocephalus and progressive headaches found to have a right cerebellopontine angle (CPA) lesion encasing multiple blood vessels and cranial nerves (CN). The lesion was resected subtotally via a retrosigmoid approach and was found to be a subependymoma. CPA subependymomas are extremely rare lesions. The neuroimaging and histopathological findings as well as a comprehensive literature review of similar cases are discussed.

Immediate Use of Continuous Positive Airway Pressure in Patients with Obstructive Sleep Apnea Following Transsphenoidal Pituitary Surgery: A Case Series.

BACKGROUND: Patients who undergo transsphenoidal pituitary resection have an elevated risk of obstructive sleep apnea (OSA) yet their outcomes and the safety of continuous positive airway pressure (CPAP) remains unclear. Our study objective was to determine the incidence of complications related to the use of early positive airway pressure following pituitary resection. METHODS: We retrospectively identified all patients who underwent endoscopic transsphenoidal pituitary tumor resection between January 1, 2005 and March 24, 2016 at our institution, including those with diagnosed or suspected OSA. We compared characteristics and postoperative complications of OSA patients who did and did not receive CPAP postoperatively. RESULTS: In total, 427 patients underwent transsphenoidal pituitary resection. Of these, 64 (15%) had OSA. Acromegaly was more common in patients with OSA (42% vs. 10%; P<0.001) but not Cushing Disease (19% vs. 16%; P=0.54). Hypoxia was more common in patients with OSA as compared to those without (14% vs. 5%; P<0.001) and one patient with OSA was reintubated compared with none in the control group (P=0.017). Eight patients had CPAP applied in the immediate postoperative period and the incidence of postoperative cerebrospinal fluid (CSF) leak, infection, and pneumocephalus was similar between OSA patients with and without CPAP. DISCUSSION: Our case series of patients with OSA who received CPAP immediately following transsphenoidal pituitary resection resulted in similar rates of surgical complications. Our results support further investigation to establish the safety of CPAP in this population.

Differential Recovery in Early- and Late-Onset Delayed Facial Palsy Following Vestibular Schwannoma Resection.

BACKGROUND: Delayed facial palsy (DFP) after resection of vestibular schwannomas (VS) is worsening of facial nerve function after an initially normal postoperative result. OBJECTIVE: To characterize different types of DFP, compare recovery rates, and review of series of outcomes in patients following resection of VS. METHODS: Between 2001 and 2017, 434 patients (51% female) with VS underwent resection. We categorized the patients who developed facial palsy into groups based on timing of onset after surgery, immediate facial palsy (IFP), early-onset DFP (within 48 h), and late-onset DFP (after 48 h). Introduction of facial nerve motor-evoked potentials (fMEP) in 2002 and a change of practice utilizing perioperative minocycline in 2005 allowed for historical analysis of these interventions. RESULTS: Mean age of study cohort was 49.1 yr (range 13-81 yr), with 19.8% developing facial palsy. The late-onset DFP group demonstrated a significantly faster recovery than the early-onset DFP group (2.8 ± 0.5 vs 47 ± 8 wk, P < .0001), had prolonged latency to palsy onset after initiating perioperative minocycline (7.3 vs 12.5 d, P = .001), and had a nonsignificant trend towards faster recovery from facial palsy with use of minocycline (2.6 vs 3.4 wk, P = .11). CONCLUSION: Given the timings, it is likely axonal degeneration is responsible for early-onset DFP, while demyelination and remyelination lead to faster facial nerve recovery in late-onset DFP. Reported anti-apoptotic properties of minocycline could account for the further delay in onset of DFP, and possibly reduce the rate and duration of DFP in the surgical cohort.

Sudden neurological deterioration due to repeated intratumoral hemorrhage in a patient with a vestibular schwannoma.

Vestibular schwannomas (VS) are the most common tumors involving the cerebellopontine angle (CPA) and the internal auditory canal (IAC). These tumors are usually slow-growing and commonly present with cranial nerve dysfunction such as hearing loss. Repeated intratumoral hemorrhage (ITH) is extremely rare with only four cases previously reported. We report the case of a 30 year old female with a right sided CP angle tumor who presented with vertigo and ataxia due to ITH. Her symptoms initially improved; however, three weeks later, she had acute onset of facial palsy and imaging confirmed rebleeding. Surgical pathology reported typical features of schwannoma. A literature review performed using the PubMed and EMBASE databases yielded four previous reports. A summary of these cases is presented and the features of ITH are discussed. Patients affected by repeated ITH present with sudden headache and ataxia. Rapid worsening of cranial nerve dysfunction such as hearing loss or facial nerve palsy is suggestive of ITH.

Natural History, Multimodal Management, and Quality of Life Outcomes of Trigeminal Schwannomas.

Background Trigeminal schwannomas are the second most common among intracranial schwannomas. These can arise from anywhere between the root and the distal extracranial branches of the trigeminal nerve. Clinical presentation depends on location and size, including but not limited to facial hypesthesia or pain, headaches, dizziness, ataxia, and diplopia. Literature is strikingly scant discussing the natural history of these lesions, while the treatment goals are heavily dependent on tumor presentation. Management decisions must be individualized to each tumor and each patient, while attempting to maximize the quality of life. We present the natural history of these lesions as well as their management by surgical resection or radiation therapy, and report long-term quality of life outcomes. Methods Between 2001 and 2015, 24 patients (66.7% female) with trigeminal schwannomas were diagnosed and managed at Vancouver General Hospital. We analyzed the clinical presentation, surgical results, resection rates, patient quality of life, and complications. To complete the evaluation, we prospectively collected 36-Item Short Form Health Survey (SF-36) quality of life assessments for comparison. Results We identified 12 patients treated with a craniotomy and surgical resection, 4 were treated with radiation therapy, while 8 patients were followed by observation. Mean age of study cohort was 49.2 years (range, 23-79 years), and most patients presented with facial hypesthesia (54.2%) and headaches (37.5%), while 37.5% were incidental findings. There were no major differences in patient demographics between the three groups. Patients offered surgery had larger lesions (mean diameter, 3.4 ± 1.1 cm) when compared with those that were irradiated or observed, and were more likely to have extracranial extension. Overall patient quality of life improved following treatment (ΔSF-36 + 12.9) at 3.9 years. Conclusions The treatment goals of trigeminal schwannomas focus on improvement in neurologic symptoms, relief of mass effect, and preservation of cranial nerve function. We demonstrate that smaller lesions found incidentally with minimal symptoms can be followed safely with serial imaging, with 1 of 9 (11.1%) progressing to require treatment over the course of 7.1 years. Management of trigeminal schwannomas should be individualized with an involvement of a multidisciplinary skull base team.

A novel scale for describing visual outcomes in patients following resection of lesions affecting the optic apparatus: the Unified Visual Function Scale.

OBJECTIVEHistorically, descriptions of visual acuity and visual field change following intracranial procedures have been very rudimentary. Clinicians and researchers have often used basic descriptions, such as "improved," "worsened," and "unchanged," to describe outcomes following resections of tumors affecting the optic apparatus. These descriptors are vague, difficult to quantify, and challenging to apply in a clinical perspective. Several groups have attempted to combine visual acuity and visual fields into a single assessment score, but these are not user-friendly. The authors present a novel way to describe a patient's visual function as a combination of visual acuity and visual field assessment that is simple to use and can be used by surgeons and researchers to gauge visual outcomes following tumor resection.METHODSVisual acuity and visual fields were combined into 3 categories designed around the definitions of legal blindness and fitness to drive in Canada. The authors then applied the scale (the Unified Visual Function Scale, or UVFS) to their previously published case series of perisellar meningiomas to document and test overall visual outcomes for patients undergoing tumor resection. The results were compared with previously documented visual loss scales in the literature.RESULTSUsing the UVFS the authors were able to capture the overall visual change; the scale was sensitive enough to define the overall visual improvement or worsening quantitatively, using categories that are clinically relevant and understandable.CONCLUSIONSThe UVFS is a robust way to assess a patient's vision, combining visual fields and acuity. The implementation of pre- and postoperative assessment is sensitive enough to assess overall change while also providing clinically relevant information for surgeons, and allows for comparisons between treatment groups.

Adult Craniopharyngioma: Case Series, Systematic Review, and Meta-Analysis.

BACKGROUND: The optimal therapeutic approach for adult craniopharyngioma remains controversial. Some advocate for gross total resection (GTR), while others advocate for subtotal resection followed by adjuvant radiotherapy (STR + XRT). OBJECTIVE: To conduct a systematic review and meta-analysis assessing the rate of recurrence in the follow-up of 3 yr in adult craniopharyngioma stratified by extent of resection and presence of adjuvant radiotherapy. METHODS: MEDLINE (1946-July 1, 2016) and EMBASE (1980-June 30, 2016) were systematically reviewed. From1975 to 2013, 33 patients were treated with initial surgical resection for adult onset craniopharyngioma at our center and were reviewed for inclusion in this study. RESULTS: Data from 22 patients were available for inclusion as a case series in the systematic review. Eligible studies (n = 21) were identified from the literature in addition to a case series of our institutional experience. Three groups were available for analysis: GTR, STR + XRT, and STR. The rates of recurrence were 17%, 27%, and 45%, respectively. The risk of developing recurrence was significant for GTR vs STR (odds ratio [OR]: 0.24, 95% confidence interval [CI]: 0.15-0.38) and STR + XRT vs STR (OR: 0.20, 95% CI: 0.10-0.41). Risk of recurrence after GTR vs STR + XRT did not reach significance (OR: 0.63, 95% CI: 0.33-1.24, P = .18). CONCLUSION: This is the first and largest systematic review focusing on the rate of recurrence in adult craniopharyngioma. Although the rates of recurrence are favoring GTR, difference in risk of recurrence did not reach significance. This study provides guidance to clinicians and directions for future research with the need to stratify outcomes per treatment modalities.

Population-Based Study of Stereotactic Radiosurgery or Fractionated Stereotactic Radiation Therapy for Vestibular Schwannoma: Long-Term Outcomes and Toxicities.

PURPOSE: To examine long-term local control of vestibular schwannoma and side effects in patients treated with stereotactic radiosurgery (SRS) and fractionated stereotactic radiation therapy (SRT) in British Columbia. METHODS AND MATERIALS: From August 1998 to May 2009, 207 patients were treated with radiation therapy (RT) at British Columbia Cancer Agency. 136 (66%) received SRS, and 71 (34%) received SRT. Dose prescriptions were 50 Gy/25 fractions for SRT and 12 Gy/1 fraction for SRS. Our multidisciplinary provincial neuro-stereotactic conference recommended SRT for tumors >3 cm and for patients with serviceable hearing (Gardner-Robertson classes I and II). RESULTS: Median follow-up was 7.7 years to the last MRI and 6.4 years to the last clinical assessment. Local control for SRS versus SRT was 94% versus 87% at 5 years and 90% versus 85% at 10 years (P=.2). Five- and 10-year actuarial rates of RT-induced trigeminal nerve dysfunction were 25% and 25% after SRS, compared with 7% and 12% after SRT (P=.01). Five- and 10-year actuarial rates of RT-induced facial nerve dysfunction were 15% and 15% after SRS, versus 13% and 15% after SRT (P=.93). In the 49 patients with serviceable hearing at baseline who were treated with SRT, hearing preservation was 55% at 3 years, 37% at 5 years, and 29% at 7 years. In multivariable analysis, better pretreatment ipsilateral pure tone average was significantly associated with hearing preservation (hazard ratio 1.03; 95% confidence interval 1.00-1.07; P=.04). CONCLUSIONS: Both SRS and SRT provided excellent long-term local control of vestibular schwannoma. Stereotactic radiosurgery was associated with higher rates of trigeminal nerve dysfunction. Even with a fractionated course, hearing preservation declined steadily with long-term audiometric follow-up.

Ipsilateral Motor Innervation Discovered Incidentally on Intraoperative Monitoring: A Case Report.

Background and importance: Lesions in the corticospinal tract above the decussation at the medullary pyramids almost universally produce contralateral deficits. Rare cases of supratentorial lesions causing ipsilateral motor deficits have been reported previously, but only ever found secondary to stroke or congenital pyramidal tract malformations. Clinical presentation: Herein, we report a case of ipsilateral corticospinal tract innervation discovered incidentally with intraoperative monitoring during a microsurgical resection of a vestibular schwannoma. Intraoperative monitoring with electrical transcranial stimulation of the frontal scalp triggered motor-evoked potentials in the ipsilateral arms. The uncrossed pathways were later confirmed with MRI tractography using diffusion tensor imaging. Conclusion: To the best of our knowledge, this is the first case of isolated ipsilateral motor innervation of the corticospinal tract discovered incidentally during a neurosurgical procedure. Given the increasing use of intraoperative monitoring, this case underscores the importance of cautious interpretation of seemingly discordant neurophysiological findings. Once technical issues have been ruled out, ipsilateral motor innervation may be considered as a possible explanation and neurosurgeons should be aware of the existence of this rare anatomic variant.

Craniotomy for perisellar meningiomas: comparison of simple (appropriate for endoscopic approach) versus complex anatomy and surgical outcomes.

OBJECTIVE Microsurgical resection of perisellar meningiomas has remained the gold standard for treatment, with extended endoscopic endonasal surgery emerging as a viable alternative. Historical microsurgical series do not distinguish based on tumor anatomy, but are being used as a comparison against endonasal surgery. In this study, the authors retrospectively reviewed and compared the anatomy of perisellar meningiomas seen at their institution. The tumors were separated into 2 groups based on whether they would be appropriate for endoscopic resection, and the authors compared the surgical outcomes. METHODS Between 2001 and 2013, 53 patients (73.6% women) with perisellar meningiomas underwent open microsurgical resection at Vancouver General Hospital performed by the senior author (R.A.). These tumors were separated into 2 groups based on their anatomy, and the authors analyzed the resection rates, surgical results, patient quality of life, and complications. RESULTS Among the 53 patients who presented with perisellar meningiomas, the authors were able to identify 18 lesions with "simple" anatomy suitable for endoscopic resection and 35 lesions with "complex" anatomy suitable for craniotomy resection. The mean age of patients in the study cohort was 57.4 years (range 33-91 years), and most patients presented with visual loss (68.0%) and visual field restriction (64.2%). There were no major differences in patient demographic data between the 2 groups. Patients with simple anatomy had smaller lesions (2.1 vs 3.5 cm; p = 0.004), no optic canal invasion (89% vs 26%; p < 0.0001), minimal vascular encasement (cortical cuff 83% vs 9%; p < 0.0001), and a rounded tumor shape (100% vs 31.8%; p = 0.0001) when compared with those with complex anatomy. The majority of lesions originated from the tuberculum sellae and planum sphenoidale. A greater degree of resection was achieved in the favorable anatomy group (99% vs 87.1%; p < 0.0001). Vision was improved or normalized in 96.6% of patients. Patients in the cohort with complex anatomy had more transient complications; there were no incidents of surgical-site infection, meningitis, or death in this series. One patient who underwent removal of a recurrent lesion experienced a CSF leak that required endoscopic repair. The overall persisting complications rate was higher in the group with complex anatomy (11.1% vs 37.1%; p = 0.0498); overall, 28.3% of patients experienced disabling complications. Patient-perceived quality of life improved in the simple anatomy group following surgery (ΔSF-36 +16.6 vs -8.4; p = 0.0045). CONCLUSIONS Extended endoscopic surgery is emerging as a viable alternative to microsurgical resection of perisellar meningiomas. The authors identified 2 patient groups based on tumor anatomy, with distinctly separate surgical outcomes. In the future, patients considered for endoscopic resection should be compared against the surgical group with simple anatomy that includes smaller tumors, no vascular encasement, and limited optic canal invasion.

Perioperative Quality of Life in Cushing's Disease.

BACKGROUND: Our study evaluated the perioperative quality of life (QoL) in Cushing's disease (CD) patients, along with correlations between patient variables and cure rate. METHODS: The 36-item Short-Form Health Survey (SF)-36 questionnaire was used to assess perioperative QoL. Patients completed one survey preoperatively and two surveys postoperatively. Retrospective chart review was conducted to collect SF-36 data as well as examine variables including: age, hospital stay, size of tumour, pathological diagnosis, timing of cure, and complication rates. Statistical analysis was conducted on the scores reported by the SF-36, and were compared with the normal Canadian population values, and to a sample of QoL from nonfunctioning pituitary tumour patients. This project was approved by University of British Columbia Research Ethics Board #H15-01572. RESULTS: In general, CD patients have relatively poor QoL that does improve as expected when cured, but not quite to normal levels. Factors associated with cure included presence of macroadenoma, confirmatory pathology, and patient age. Postoperative timing of cure appears to affect the durability of cure, with an immediate cure having a higher durability rate than delayed cure. Most recurrences occurred within 10 months postoperatively. CONCLUSIONS: This review of the perioperative QoL in CD helps to illustrate how QoL changes throughout the treatment process, how QoL compares to normal Canadian population levels, and how QoL compares to patients with nonfunctioning pituitary adenomas. As treatment outcome has such a high impact on QoL, the variables identified in this study will help to better inform patients about the treatment course.

Role of Facial Nerve Motor-Evoked Potential Ratio in Predicting Facial Nerve Function in Vestibular Schwannoma Surgery Both Immediate and at 1 Year.

OBJECTIVE: To determine whether transcranial electrical stimulation-induced facial motor-evoked potential (FMEP) monitoring of the facial nerve (FN) during vestibular schwannoma (VS) tumor resection can predict both immediate and 1 year postoperative FN functional outcome. DESIGN: Prospective consecutive non-comparative observational case series. SETTING: Tertiary referral center. MAIN OUTCOME MEASURES: Facial function, immediate post operation and at 1 year using House-Brackmann (HB) grading scale. METHODS: The study included 367 consecutive patients (men 178; women 189; age 13-81 years) monitored during primary sporadic VS microsurgery between November 2002 and April 2015. Neurofibromatosis type II, revision surgery, previous radiotherapy treatment, preoperative facial nerve weakness, and non-VS cases were excluded retrospectively during analysis of data. Data of facial function were missing from eight patients at 1 year and were excluded. The correlation between the final-to-baseline FMEP ratio and immediate and 1 year facial nerve function was examined. RESULTS: Using logistic regression model, the cut-off points of FMEP ratio were 0.62 (PPV 0.96) and 0.59 (PPV 0.98) which predicted satisfactory FN function (HB grades 1 or 2) immediately postoperative and at 1 year after surgery, respectively. CONCLUSION: Transcranial electrical stimulation FMEP is a valuable tool for monitoring facial nerve function during resection of vestibular schwannoma. Maintaining a FMEP event-to-baseline ratio of 60% or greater is predictive of satisfactory long-term FN function.