Kerezoudis, Panagiotis

BACKGROUND AND OBJECTIVES: The anterior nucleus of the thalamus (ANT) is a common target for deep brain stimulation (DBS) for drug-resistant epilepsy (DRE). However, the surgical approach to the ANT remains challenging because of its unique anatomy. This study aims to summarize our experience with the posterior temporo-parietal extraventricular (TPEV) approach targeting the ANT for DBS in DRE. METHODS: We performed a retrospective analysis of patients with DRE who underwent ANT-DBS using the TPEV approach between January 2011 and February 2021. Subjects with at least 6-month follow-up were eligible. The final lead position and number of active contacts targeting the anteroventral nucleus (AV) of the ANT were assessed using Lead-DBS. Mean seizure frequency reduction percentage and responder rate (≥50% decrease in seizure frequency) were determined. RESULTS: Thirty-one patients (mean age: 32.9 years; 52% female patients) were included. The mean follow-up period was 27.6 months ± 13.9 (29, 16-36). The mean seizure frequency reduction percentage was 65% ± 26 (75, 50-82). Twenty-six of 31 participants (83%) were responders, P < .001. Two subjects (6%) were seizure-free for at least 6 months at the last evaluation. Antiepileptic drugs dose and/or number decreased in 17/31 subjects (55%). The success rate for placing at least 1 contact at AV was 87% (27/31 patients) bilaterally. The number of active contacts at the AV was significantly greater in the responder group, 3.1 ± 1.3 (3, 2-4) vs 1.8 ± 1.1 (2, 1-2.5); P = .041 with a positive correlation between the number of active contacts and seizure reduction percentage; r = 0.445, R 2 = 0.198, P = .012. CONCLUSION: The TPEV trajectory is a safe and effective approach to target the ANT for DBS. Future studies are needed to compare the clinical outcomes and target accuracy with the standard approaches.

Background Traumatic posterior cerebral artery (tPCA) dissection and dissecting aneurysms are rare and constitute a challenging clinical entity. Objective We analyze existing literature on tPCA dissection and present our institutional experience. Methods We retrospectively queried our database for tPCA isolated dissection or dissecting aneurysms from 2008 until now and conducted a systematic literature review of published cases. We analyzed the clinical and radiographic characteristics and treatment outcomes of tPCA dissection. Results Including our case, a total of 11 cases with either isolated dissection ( n = 2) or dissecting aneurysms ( n = 9) were included. The median age was 27 years, and 45% were females. The median interval between trauma and tPCA dissection diagnosis was nine days. Mental status declined in four (36%) patients. Half of the patients demonstrated tentorial subdural hematoma on head CT. Ischemic stroke was detected in three (43%) patients. Four (36%) patients were conservatively managed, one (9.1%) patient was treated with surgical clipping of the proximal PCA, and six patients underwent endovascular treatments. The complication rate was 20%. Immediate total occlusion was demonstrated in five patients (100%), and the conservatively managed case showed immediate, spontaneous thrombosis of the aneurysm. Glasgow Coma Scale scores were 15 in eight (89%) and 14 in one (11%) patients at the last clinical follow-up with a median of six months. The mortality and retreatment rates were null. Conclusions tPCA dissection is diagnosed late and commonly affects the young population. The clinical outcome for this condition is typically favorable. Current endovascular techniques showed considerable efficacy and safety.

Abstract Background Hemangioblastomas pose an inherent surgical risk due to the potential for high intraoperative blood loss, especially in larger tumors. One approach to minimize this risk is to use preoperative embolization. Herein, we present our institutional experience treating large and giant cerebellar hemangioblastomas. Methods We performed a retrospective chart review of 19 patients with cerebellar hemangioblastomas that had a maximal diameter of >3 cm. We performed a literature review and included individual patient-level data that met our >3 cm diameter cerebellar hemangioblastoma inclusion criteria. Results Our cohort consisted of 19 patients that received a total of 20 resections for their cerebellar hemangioblastomas. Preoperative embolization was utilized in eight cases (38.1%). One patient experienced transient neurological complications after embolization (12.5%). Tumors of patients in the embolization group had larger median total, solid, and cystic volumes and were more likely to involve the cerebellopontine angle than those in the non-embolized group. Compared with non-embolized patients, embolized patients had less decrease in their hemoglobin, lower volumes of estimated blood loss, reduced rates of postoperative complications and permanent deficits, and greater instances of neurological improvement. The larger cohort (obtained from the combining our cohort with patients identified during a literature review) consisted of 99 patients with 39 receiving preoperative embolization. Conclusion It is important to examine individual patient characteristics when determining eligibility for preoperative embolization. However, improvements in endovascular techniques have made preoperative embolization a safe and effective procedure with minimal risks that can be performed in many patients.

OBJECTIVE Facial nerve palsy is a debilitating condition that can arise from iatrogenic, traumatic, or congenital causes. One treatment to improve function of the facial muscles after facial nerve injury is hypoglossal-to-facial nerve anastomosis (HFA). HFA’s efficacy and predictors of its success vary in the literature. Here, the authors present a patient-level analysis of a literature-based cohort to assess outcomes and investigate predictors of success for HFA. METHODS Seven electronic databases were queried for studies providing baseline characteristics and outcomes of patients who underwent HFA. Postoperative outcomes were measured using the House-Brackmann (HB) grading scale. A change in HB grade of 3 points or more was classified as favorable. A cutoff value for time to anastomosis associated with a favorable outcome was determined using the Youden Index. RESULTS Nineteen articles with 157 patients met the inclusion criteria. The mean follow-up length was 27.4 months, and the mean time to anastomosis after initial injury was 16 months. The end-to-side and end-to-end anastomosis techniques were performed on 84 and 48 patients, respectively. Of the 130 patients who had available preoperative and postoperative HB data, 60 (46.2%) had a favorable outcome. Time from initial injury to anastomosis was significantly different between patients with favorable and unfavorable outcomes (7.3 months vs 29.2 months, respectively; p < 0.001). The optimal cutoff for time to anastomosis to achieve a favorable outcome was 6.5 months (area under the curve 0.75). Patients who underwent anastomosis within 6.5 months of injury were more likely to achieve a favorable outcome (73% vs 31%, p < 0.001). CONCLUSIONS HFA is an effective method for restoring facial nerve function. Favorable outcomes for facial nerve palsy may be more likely to occur when time to anastomosis is within a 6.5-month window.

Neurosurgical education is a continually developing field with an aim of training competent and compassionate surgeons who can care for the needs of their patients. The Mayo Clinic utilizes a unique mentorship model for neurosurgical training. In this paper, the authors detail the historical roots as well as the logistical and experiential characteristics of this teaching model. This model was first established in the late 1890s by the Mayo brothers and then adopted by the Mayo Clinic Department of Neurological Surgery at its inception in 1919. It has since been implemented enterprise-wide at the Minnesota, Florida, and Arizona residency programs. The mentorship model is focused on honing resident skills through individualized attention and guidance from an attending physician. Each resident is closely mentored by a consultant during a 2- or 3-month rotation, which allows for exposure to more complex cases early in their training. In this model, residents take ownership of their patients’ care, following them longitudinally during their hospital course with guided oversight from their mentors. During the chief year, residents have their own clinic, operating room (OR) schedule, and OR team and service nurse. In this model, chief residents conduct themselves more in the manner of an attending physician than a trainee but continue to have oversight from staff to provide a “safety net.” The longitudinal care of patients provided by the residents under the mentorship model is not only beneficial for the trainee and the hospital, but also has a positive impact on patient satisfaction and safety. The Mayo Clinic Mentorship Model is one of many educational models that has demonstrated itself to be an excellent approach for resident education.