Meyer, Jenna H.

BACKGROUND AND OBJECTIVES: Aneurysm risk prediction remains an imprecise science that places patients at risk for either over or undertreatment. Machine learning (ML) models may improve clinical practice by adding precision to risk assessment. This study aims to comprehensively assess the current landscape of ML applications in predicting the risk of aneurysm rupture and compare the performance with the widely used PHASES score. METHODS: A systematic review of PubMed, Scopus, and Web of Science was conducted. All studies using ML tools to predict the rupture risk of intracranial aneurysms were included. Meta-analysis was conducted with consideration to the ML algorithms and compared with the PHASES score. RESULTS: Thirty-six studies involving 22 462 patients were included in the final analysis. ML techniques, including 124 models using 25 algorithms, were employed. Among various ML models, while they had comparable diagnostic performance, deep learning exhibited a slightly better performance profile (sensitivity = 0.792, specificity = 0.788, and accuracy = 0.778 in external validation). Based on our analysis, ML, regardless of the algorithm, provides comparable sensitivity (0.743 vs 0.771, P = .60) and higher specificity (0.763 vs 0.507, P < .01) compared with the PHASES score. Consistently, pooling the area under the receiver operating characteristic curve (AUC) for 60 ML models and 5 PHASES score data, ML models exhibited higher AUC (0.84 vs 0.64, P < .01). Using hemodynamic parameters as input for models improved specificity ( P < .01) in the test sets without any significant changes in the sensitivity. The later improvement was not observed in the external validation sets. CONCLUSION: ML techniques have the potential to enhance the prediction of intracranial aneurysm rupture compared with traditional approaches, like the PHASES score. Incorporating hemodynamic parameters may further enhance the accuracy of ML models. Feature prospective studies are required to validate the utility of ML models for clinical integration.

BACKGROUND AND OBJECTIVES: Access to the amygdala and hippocampus (A/H) is complex. To address the limitations and invasiveness of traditional approaches, including the Transsylvian, Subtemporal, and Supracerebellar infratentorial approaches, we developed the suprapetrous infratemporal (SPIT) approach. This study describes the nuances of this approach in both cadaveric studies and clinical cases. METHODS: Three unilateral exposures were performed using microscopic and endoscopic methodologies in the SPIT approach. After cadaveric investigation, this approach was successfully implemented in representative clinical cases. RESULTS: The SPIT approach enabled direct access to the inferior A/H, circumventing the requirement for temporal lobe retraction and detachment of the temporal lobe from the dura through a subtemporal route by drilling the upper part of the mastoid, consequently mitigating tension on the vein of Labbé. This enabled a bottom-up view because one would gain with a zygomatic osteotomy and forward projection like a mini-posterior petrosal view by using a transmastoid view, without cutting down the zygomatic arch and opening the dura subtemporally, limiting patient pain and preventing case comorbidity. The SPIT approach was performed in 2 cases of mesial temporal cavernoma presenting with seizures. The lesion was visualized intraoperatively and was successfully removed in these cases. The postoperative course was excellent with no complications, and gross total resection was radiographically confirmed with Engel Class 1a seizure freedom. CONCLUSION: The SPIT approach is a complementary approach for inferior A/H disease, combining the combined middle fossa approach modified for intradural pathology. Limited drilling of the upper aspect of the mastoid with a medial dural opening at the level of the arcuate eminence provides a direct trajectory with minimal brain retraction. Additional research encompassing a larger patient cohort and extended follow-up periods is required to substantiate the advantages of SPIT in the management of inferior A/H lesions.

BACKGROUND Hirayama disease (HD), also known as juvenile spinal muscular atrophy, is a rare condition in which flexion of the cervical neck causes compression and ischemic changes to the anterior horns of the spinal cord. Here the authors presented the first reported case of HD in North America that was successfully treated via surgical intervention. OBSERVATIONS The patient was a 15-year boy with insidious onset upper limb weakness and atrophy. His findings were a classic presentation of HD although his complex history and relative rarity of the disease caused him to remain undiagnosed for months. After conservative management via cervical collar failed, the patient was successfully treated via C5-C7 anterior cervical discectomy and fusion. The patient’s symptoms stabilized by the 3-month follow-up. LESSONS The diagnosis of HD is easy to miss because of the lack of reporting and widespread knowledge of this condition in North America. Thus, when presented with a case of insidious onset limb weakness in a juvenile patient, HD should be placed on the differential list and verified with cervical flexion magnetic resonance imaging. Additionally, surgical intervention should be considered a safe and effective option for HD when conservative methods have failed.

Abstract Chiari malformation is a relatively rare condition involving herniation of the brain out of the skull and into the spinal canal. The purpose of this review was to identify top contributors to the world of Chiari research, as well as to highlight the publications which have shaped our perception of this condition.We performed a search of the Web of Science between the years 1900 and 2021 using the terms “Chiari I malformation”, “Arnold Chiari malformation”, “Chiari II malformation”, “Chiari malformation type 1”, and “Chiari malformation type 2”. After screening for duplicates and assessing for relevance using two independent reviewers, the top 100 most frequently cited articles were collected and sorted. These articles were published between the years 1938 and 2015 and were cited 145.7 times on average, ranging from 79 to 724 citations per article. Authored by Milhorat et al., the 1999 Neurosurgery article “Chiari I Malformation Redefined: Clinical and Radiographic Findings for 364 Symptomatic Patients” received most citations (724 citations). Journal of Neurosurgery contributed the most articles to the top-100 with 21 publications. The University of California system accounted for the most articles by institution (8 of 100) and the USA was the highest contributing country (62%). In this study, we identified and analyzed the most cited articles on Chiari malformations to gain a better understanding of the publications contributing our knowledge of this disorder. This analysis serves both as a way of gauging the current state of research and of recognizing gaps where further research is necessary.

Abstract IntroductionRadiotherapy is considered standard of care for adjuvant peri-operative treatment of many spinal tumors, including those with instrumented fusion. Unfortunately, radiation treatment has been linked to increased risk of pseudoarthrosis. Newerfocused radiotherapy strategies with enhanced conformalitycould offer improved fusion rates for these patients, but this has not been confirmed.MethodsWe performed a retrospective analysis of patients at three tertiary care academic institutions withprimary and secondary spinal malignancies that underwent resection, instrumented fusion, and peri-operative radiotherapy. Two board certified neuro-radiologists used theLenke fusion score to grade fusion status at6 and 12-months after surgery. Secondary outcomes includedclinical pseudoarthrosis, wound complications, and the effect of radiation timing, radiobiological dose delivered, the use of photons versus protons, tumor type, tumor location,and use of autograft on fusion outcomes.ResultsAfter reviewof 1252 spinal tumor patients, there were 60 patients with at least 6 months follow-up that were included in our analyses. Twenty-five of these patients received focused radiotherapy,20 patients received conventional radiotherapy, and 15 patients were treated with protons. There was no significant difference between the groups for covariates such assmoking status,obesity, diabetes, intraoperative use of autograft, and use of peri-operative chemotherapy. There was a significantly higher rate of fusion for patients treated with focused radiotherapy compared to those treated with conventional radiotherapy at 6-months (64.0% versus 30.0%, Odds ratio: 4.15, p=0.036) and 12-months (80.0% versus 42.1%, OR: 5.50, p=0.022). There was a significantly higher rate of clinical pseudoarthrosis in the conventional radiotherapy cohortcompared to patients in the focused radiotherapy cohort (19.1% versus 0%,p=0.037). There was no difference in fusion outcomes for any of the secondary outcomes except for use of autograft. The use ofintra-operative autograft was associated with an improved fusion at 12-months (66.7% versus 37.5%, OR: 3.33, p=0.043). ConclusionFocused radiotherapy may be associated withan improved rate of fusion and clinical pseudoarthrosis when compared to conventional radiation delivery strategiesin patients with spinal tumors.Use of autograft at the time of surgery may be associated with improved 12-month fusion rates.Further large-scale prospective and randomized controlled studies are needed to better stratify the effects of radiation delivery modality in these patients.