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Summary: Objective: The clinical course and underlying molecular causes in patients with glioblastoma presenting with seizures are poorly understood. Here we investigated clinical features and carrier systems as well as a transaminase relevant in glutamate homeostasis in patients with glioblastoma. Methods: We performed a retrospective analysis of our clinical glioma database for clinical data during a 2‐year period. Patients with glioblastoma were divided into 2 groups: symptomatic and asymptomatic for seizures. Magnetic resonance imaging (MRI) scans and tissue samples from both groups were investigated. A Cox regression analysis was performed for survival and clinical and molecular features. Results: One hundred three patients diagnosed with glioblastoma in this period were identified. Twenty‐three patients were symptomatic with seizures (22.3%). All were IDH‐1/2 wild‐type. We found no significant difference in the tumor localization between the groups. Patients with seizures from glioblastoma had significantly smaller tumors, which caused less edema compared to nonepileptogenic tumors. A significantly increased up‐regulation of glutamate carrier systems was evident in symptomatic tumors compared to asymptomatic tumors. Moreover, there seems to be an oversupply of glutamate in symptomatic tumors due to dysregulation in glutamate synthesis. Significance: Glioblastoma presenting with seizures is morphologically different from asymptomatic tumors. Furthermore, we were able to show that the molecular profile of these tumors, particularly glutamate homeostasis controlling systems, is significantly different. [ABSTRACT FROM AUTHOR]

Introduction: Deep brain stimulation (DBS) within the ventrolateral thalamus with directional leads may result in improved tremor suppression and reduced adverse events. Methods: Nine essential tremor patients (1 female; mean age 69 yrs; average disease duration 23 yrs; follow-up 1 to 8 months) were implanted bilaterally (8) with directional leads into the ventrolateral thalamus and subthalamic region (Infinity™; St. Jude Medical). Intraoperatively clinical effects elicited by stimulation in different directions via bipolar activation of corresponding segments pointing into the same direction (lower segment = cathode) were assessed. Monopolar reviews involved the assessment of tremor suppression, including quantitative accelerometer assessments to be completed for some patients, and side effects, in particular paraesthesias. Patients and raters were blinded with regard to the direction of DBS (chosen in random order) and stimulation amplitude. Clinical Global Impression (CGI; 1= very much improved, 7=very much worsened) scale was used to track subjective treatment responses over time. Results: There were no adverse events related to surgery or implanted hardware. All patients exhibited microlesioning effects followed by sustained tremor suppression with DBS. The improvement was rated CGI = 2.6±2.1. Intraoperative assessments revealed a lower threshold for paraesthesia if stimulation was performed into the posterior-(medial and lateral) direction. Monopolar review revealed differential thresholds for tremor suppression and paraesthesias that were very variable among patients, and for three electrodes paraesthesia thresholds did not differ between directions or were lower with stimulation in the anterior direction. Tetanic muscle contractions could not be elicited to an extent allowing meaningful comparisons. In two patients permanent stimulation with one of both electrodes was performed in a directional mode in order to widen the therapeutic window or because gait ataxia had worsened under ring mode stimulation. Conclusion: Directional stimulation maps did not reveal a uniform pattern with regard to tremor suppression and thresholds for paraesthesia. In particular the influence of directional DBS on the therapeutic windows was highly variable among patients. This may be related to actual contact positions, electrode angulations, individual anatomy and biophysical characteristics of directional DBS that need to be unraveled. [ABSTRACT FROM AUTHOR]