Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Stereotactic procedures are used to manage a diverse set of patients across a variety of clinical contexts. The stereotactic devices and software used in these procedures vary between surgeons, but the fundamental principles that constitute safe and accurate execution do not. The aim of this work is to describe these principles to equip readers with a generalizable knowledge base to execute and understand stereotactic procedures. METHODS:A combination of a review of the literature and empirical experience from several experienced surgeons led to the creation of this work. Thus, this work is descriptive and qualitative by nature, and the literature is used to support instead of generate the ideas of this framework. RESULTS:The principles detailed in this work are categorized based on 5 clinical domains: imaging, registration, mechanical accuracy, target planning and adjustment, and trajectory planning and adjustment. Illustrations and tables are used throughout to convey the concepts in an efficient manner. CONCLUSION/CONCLUSIONS:Stereotactic procedures are complex, requiring a thorough understanding of each step of the workflow. The concepts described in this work enable functional neurosurgeons with the fundamental knowledge necessary to provide optimal patient care.

OBJECTIVES/OBJECTIVE:To assess a decade of experience of treating patients with high hearing risk cerebellopontine angle (CPA) epidermoid lesions and examine factors influencing postoperative outcomes, particularly hearing preservation. STUDY DESIGN/METHODS:Retrospective chart review. SETTING/METHODS:Single tertiary-referral center. PATIENTS/METHODS:Adults with CPA epidermoid lesions who presented with hearing loss or evidence of lesion involving vestibulocochlear nerve. INTERVENTIONS/METHODS:The studied intervention was microsurgical resection. MAIN OUTCOME MEASURES/METHODS:Main outcome measures included extent of resection, hearing preservation rate for patients with postoperative audiograms, and disease progression. RESULTS:Twenty-three adults with an average tumor volume of 15.63 ± 16.2 cm3 were included. Five lesions (22%) involved the full internal auditory canal (IAC), 11 (48%) had partial involvement, and 5 (22%) were IAC sparing. Most patients with IAC involvement (88%) had circumferential invasion of the canal. Patients underwent either a retrosigmoid (18, 79%) or combined retrolabyrinthine transpetrosal approach (5, 22%), and gross total resection was achieved in most cases (13, 57%). Of 12 patients with postoperative audiograms, 10 (83%) had preoperative hearing preserved. There was no statistically significant change in hearing scores with treatment based on preoperative extent of IAC involvement. Ten patients (43%) had residual lesions postoperatively, and 6 exhibited progression. One patient ultimately required reoperation 6 years after initial surgery. CONCLUSIONS:Preoperative hearing was preserved in the majority of the patients who underwent resection of CPA epidermoids via a retrosigmoid or transpetrosal approach. CPA epidermoids often invaded the IAC; however, degree of invasion was not associated with hearing outcomes.

Cerebral arteriovenous malformations (AVMs) are congenital vascular anomalies that can lead to severe complications, including hemorrhage and neurological deficits. This study compares the outcomes of microsurgical resection and stereotactic radiosurgery (SRS) for SM grade I and II AVMs. Out of a large multicenter registry, we identified 180 matched patients with SM grade I and II AVMs treated with either microsurgical resection or SRS between 2010 and 2023. The primary outcomes were AVM obliteration rates and complications; secondary outcomes included neurological status and functional outcomes measured by the modified Rankin Scale (mRS). Propensity score matching (PSM) was utilized to ensure comparability between treatment groups. After PSM, 90 patients were allocated to each treatment group. Significant differences were observed in complete obliteration rates, with resection achieving higher rates compared to SRS in overall cases (97.8% vs. 60.0%, p < 0.001), unruptured AVMs (100% vs. 58.3%, p < 0.001), and ruptured AVMs (95.2% vs. 61.9%, p < 0.001). Functional improvement rates were similar between the groups for overall cases (67.2% in resection vs. 66.7% in SRS, p = 0.95), unruptured AVMs (55.2% in resection vs. 55.6% in SRS, p > 0.9), and ruptured AVMs (78.1% in resection vs. 74.1% in SRS, p = 0.7). Symptomatic complication rates were identical between the groups (11.1% each, p > 0.9), while permanent complication rates were comparable (6.7% in resection vs. 5.6% in SRS, p = 0.8). Resection demonstrated significantly higher complete obliteration rates compared to SRS across all cases, including unruptured and ruptured AVMs. Functional improvement rates were similar between the two treatment groups, with no significant differences in symptomatic or permanent complication rates.

Seizures occur in 20-45% of patients with cerebral arteriovenous malformations (AVMs) and can potentially influence their quality of life. Some studies have suggested risk factors influencing their development, but the evidence is limited to small cohorts. To analyze seizure presentation and factors influencing seizure development in patients with cerebral AVMs using a multi-institutional consortium. Retrospective multicenter registry from multiple centers in North America and Europe of patients aged 1 to 89 years who had undergone any intervention for brain AVMs between January 2010 and December 2023. Demographics, functional assessment (modified Rankin Scale; mRS), and AVM characteristics, were evaluated to assess for relationship with seizures using a multivariate generalized linear mixed-effects model. 1,005 AVM patients were analyzed; the median age was 42, 73% had a baseline mRS ≤ 2. The median nidus size was 2.2 cm, and most AVMs were Spetzler-Martin grade II (37%). Seizure was the presenting symptom in 237 patients (24%). After adjusting for significant variables, patient-specific factors associated with seizures were younger age (OR 0.99, CI95% 0.98-1), male sex (OR 1.65, CI95% 1.18-2.30), and smoking history (OR 1.69, CI95% 1.17-2.44). AVM-specific factors associated with seizures included rupture status (OR 0.42, CI95% 0.30-0.61); eloquent cortex (OR 1.61, CI95% 1.13-2.29); frontal (OR 1.54, CI95% 1.01-2.35), temporal (OR 1.93, CI95% 1.26-2.96) and parietal (OR 1.71 CI95% 1.08-2.71) location; larger nidal size (OR = 1.23, CI95% 1.08-1.39), and superficial draining vein location (OR 1.86, CI95% 1.15-3.01). In this multicenter consortium, after controlling for significant variables, the incidence of AVM-related seizures was associated with younger age, male sex, smoking history, larger AVMs, eloquent locations, and AVMs in the frontal, temporal, and parietal cortices. Conversely, rupture status, deep venous drainage, and cerebellar locations were negatively associated with seizures.

INTRODUCTION/UNASSIGNED:The impact of multiple feeding arteries on clinical outcomes of cerebral arteriovenous malformations (AVMs) is not well understood. This study aims to compare outcomes between AVMs with multiple versus single feeding arteries. PATIENTS AND METHODS/UNASSIGNED:Data from the Multicenter International Study for Treatment of Brain AVMs (MISTA) consortium were analyzed. Propensity score matching (PSM) was used to balance cohorts. Subgroup analysis was conducted for ruptured and unruptured AVMs and different treatment options, and multivariable logistic regression was applied to assess the impact of feeding artery origin. RESULTS/UNASSIGNED: = 0.002). DISCUSSION AND CONCLUSION/UNASSIGNED:AVMs with a single feeding artery were more likely to present with rupture, but no significant differences in obliteration rates or complications were observed between the groups after PSM. These findings suggest that while the number of feeding arteries may influence the initial presentation, it does not appear to impact overall treatment success or patient prognosis. Further prospective studies are needed to confirm these findings.

BACKGROUND:Arteriovenous malformations (AVMs) are complex vascular anomalies with a high risk of hemorrhage and neurological deficits, especially when located in eloquent brain regions. The eloquence of an AVM location is a critical factor in the treatment planning, influencing both the risk of complications and long-term functional outcomes. This study aims to compare outcomes between eloquent and non-eloquent AVMs. METHODS:This multicenter, retrospective study utilized data from the Multicenter International Study for Treatment of Brain AVMs (MISTA) consortium. Patients with eloquent and non-eloquent AVMs were compared on baseline characteristics, angiographic outcomes, and functional outcomes using the modified Rankin Scale (mRS). Propensity score weighting (IPTW) was applied to adjust for confounding variables. RESULTS:The study included 1,013 patients, with 498 (49.2%) AVMs located in eloquent regions and 515 (50.8%) in non-eloquent regions. In unadjusted analysis, eloquent AVMs had lower complete obliteration rates (67.6% vs. 79.5%, OR: 0.53, 95% CI: 0.39-0.72, p < 0.001) and higher complication rates (24.5% vs. 19.0%, OR: 1.38, 95% CI: 1.02-1.86, p = 0.03) compared to non-eloquent AVMs. After IPTW adjustment, eloquent AVMs continued to show significantly higher odds of overall complications (OR: 1.68, 95% CI: 1.12-2.52, p = 0.01) and symptomatic complications (OR: 1.77, 95% CI: 1.12-2.80, p = 0.01). Secondary analysis within the eloquent group indicated that embolization was linked to an elevated risk of complications. Surgery and radiosurgery showed comparable functional outcomes at last follow-up and complications rates with higher complete obliteration rates in surgery. CONCLUSION/CONCLUSIONS:AVMs in eloquent brain areas present higher risks of complications and lower obliteration rates, emphasizing the need for cautious, individualized treatment planning. Within the eloquent group, embolization increased the risk of complications, while surgery and radiosurgery showed comparable functional outcomes at last follow-up and complication rates with higher complete obliteration rates in surgery. These findings highlight the importance of location in AVM management and support further research focusing on comparing treatment strategies for AVMs in eloquent brain areas.

BACKGROUND:Spetzler-Martin (SM) Grade III brain arteriovenous malformations (BAVMs) represent a transitional risk zone between low- and high-grade BAVMs, characterized by diverse angioarchitecture. The primary treatment options are endovascular embolization, microsurgical resection (MS), and stereotactic radiosurgery (SRS). This study compares the efficacy and outcomes of MS and SRS. METHODS:We conducted a multicenter, retrospective study involving patients from the MISTA database with SM Grade III BAVMs treated with MS or SRS between 2010 and 2023. Propensity matching was based on age, favorable modified Rankin Score (mRS) at presentation, nidus size, rupture status, location depth, and eloquence. RESULTS:, p = 0.6) were similar. MS showed higher obliteration rates (93.3 %) compared to SRS (46.7 %) at the last follow-up (p < 0.001). The median time to obliteration post-SRS was 31.5 months (IQR: 15.3-60.0). SRS obliteration rates were 19 %, 29 %, and 59 % at 24, 36, and 60 months, respectively. Overall complication rates (MS: 30 % vs. SRS: 20 %, p = 0.4) and permanent complications (MS: 10 % vs. SRS: 13.3 %, p > 0.9) were similar. Hemorrhage occurred once in the MS group and none in the SRS (p > 0.9). Favorable outcomes (mRS 0-2) were higher with SRS than MS (93.3 % vs 80.0 %, p = 0.3), with one AVM-related mortality in the MS group. CONCLUSION/CONCLUSIONS:MS and SRS are viable treatments for SM Grade III BAVMs. Treatment choice should be individualized by a multidisciplinary team, considering patient goals.

The adoption of large language models (LLMs) in healthcare demands a careful analysis of their potential to spread false medical knowledge. Because LLMs ingest massive volumes of data from the open Internet during training, they are potentially exposed to unverified medical knowledge that may include deliberately planted misinformation. Here, we perform a threat assessment that simulates a data-poisoning attack against The Pile, a popular dataset used for LLM development. We find that replacement of just 0.001% of training tokens with medical misinformation results in harmful models more likely to propagate medical errors. Furthermore, we discover that corrupted models match the performance of their corruption-free counterparts on open-source benchmarks routinely used to evaluate medical LLMs. Using biomedical knowledge graphs to screen medical LLM outputs, we propose a harm mitigation strategy that captures 91.9% of harmful content (F1 = 85.7%). Our algorithm provides a unique method to validate stochastically generated LLM outputs against hard-coded relationships in knowledge graphs. In view of current calls for improved data provenance and transparent LLM development, we hope to raise awareness of emergent risks from LLMs trained indiscriminately on web-scraped data, particularly in healthcare where misinformation can potentially compromise patient safety.

BACKGROUND:Arteriovenous malformations (AVMs) are uncommon cerebral lesions that can cause significant neurological complications. Surgical resection is the gold standard for treatment, but endovascular embolization and stereotactic radiosurgery (SRS) are viable alternatives. OBJECTIVE:To compare the outcomes of endovascular embolization versus SRS in the treatment of AVMs with Spetzler-Martin grades I-III. METHODS:This study combined retrospective data from 10 academic institutions in North America and Europe. Patients aged 1 to 90 years who underwent endovascular embolization or SRS for AVMs with Spetzler-Martin grades I-III between January 2010 and December 2023 were included. RESULTS:The study included 244 patients, including 84 who had endovascular embolization and 160 who had SRS. Before propensity score matching (PSM), complete obliteration at the last follow-up was achieved in 74.5% of the SRS group compared with 57.8% of the embolization group (OR=0.47; 95% CI 0.26 to 0.48; P=0.01). After propensity score matching, SRS still achieved significantly higher occlusion rates at last follow-up (78.9% vs 55.3%; OR=0.32; 95% CI 0.12 to 0.90; P=0.03).Hemorrhagic complications were higher in the embolization group than in the SRS group, although this difference did not reach statistical significance after PSM (13.2% vs 2.6%; OR=5.6; 95% CI 0.62 to 50.47; P=0.12). Similarly, re-treatment rate was higher in the embolization group (10.5% vs 5.3%; OR=2.11; 95% CI 0.36 to 12.31; P=0.40) compared with the SRS group. CONCLUSION/CONCLUSIONS:Our findings indicate that SRS has a significantly higher obliteration rate at last follow-up compared with endovascular embolization. Also, SRS has a higher tendency for fewer hemorrhagic complications and lower re-treatment rate. Further prospective studies are needed.