Stereo-EEG recordings extend known distributions of canonical movement-related oscillations.

Objective.Previous electrophysiological research has characterized canonical oscillatory patterns associated with movement mostly from recordings of primary sensorimotor cortex. Less work has attempted to decode movement based on electrophysiological recordings from a broader array of brain areas such as those sampled by stereoelectroencephalography (sEEG), especially in humans. We aimed to identify and characterize different movement-related oscillations across a relatively broad sampling of brain areas in humans and if they extended beyond brain areas previously associated with movement.Approach.We used a linear support vector machine to decode time-frequency spectrograms time-locked to movement, and we validated our results with cluster permutation testing and common spatial pattern decoding.Main results.We were able to accurately classify sEEG spectrograms during a keypress movement task versus the inter-trial interval. Specifically, we found these previously-described patterns: beta (13-30 Hz) desynchronization, beta synchronization (rebound), pre-movement alpha (8-15 Hz) modulation, a post-movement broadband gamma (60-90 Hz) increase and an event-related potential. These oscillatory patterns were newly observed in a wide range of brain areas accessible with sEEG that are not accessible with other electrophysiology recording methods. For example, the presence of beta desynchronization in the frontal lobe was more widespread than previously described, extending outside primary and secondary motor cortices.Significance.Our classification revealed prominent time-frequency patterns which were also observed in previous studies that used non-invasive electroencephalography and electrocorticography, but here we identified these patterns in brain regions that had not yet been associated with movement. This provides new evidence for the anatomical extent of the system of putative motor networks that exhibit each of these oscillatory patterns.

Effects of 24-hour versus night-float call schedules on the clinical and operative experiences of postgraduate year 2 and 3 neurosurgical residents.

OBJECTIVE: To comply with the removal of the 88-hour week exemption and to support additional operative experience during junior residency, Oregon Health & Science University (OHSU) switched from a night-float call schedule to a modified 24-hour call schedule on July 1, 2019. This study compared the volumes of clinical, procedural, and operative cases experienced by postgraduate year 2 (PGY-2) and PGY-3 residents under these systems. METHODS: The authors retrospectively studied billing and related clinical records, call schedules, and Accreditation Council for Graduate Medical Education case logs for PGY-2 and PGY-3 residents at OHSU, a tertiary academic health center, for the first 4 months of the academic years from 2017 to 2020. The authors analyzed the volumes of new patient consultations, bedside procedures, and operative procedures performed by each PGY-2 and PGY-3 resident during these years, comparing the volumes experienced under each call system. RESULTS: Changing from a PGY-2 resident-focused night-float call system to a 24-hour call system that was more evenly distributed between PGY-2 and PGY-3 residents resulted in decreased volume of new patient consultations, increased volume of operative procedures, and no change in volume of bedside procedures for PGY-2 residents. PGY-3 residents experienced a decrease in operative procedure volume under the 24-hour call system. CONCLUSIONS: Transition from a night-float system to a 24-hour call system altered the distribution of clinical and procedural experiences between PGY-2 and PGY-3 residents. Further research is necessary to understand the impact of these changes on educational outcomes, quality and safety of patient care, and resident satisfaction.

Safety of intra-arterial chemotherapy with or without osmotic blood-brain barrier disruption for the treatment of patients with brain tumors.

Background: Intra-arterial administration of chemotherapy with or without osmotic blood-brain barrier disruption enhances delivery of therapeutic agents to brain tumors. The aim of this study is to evaluate the safety of these procedures. Methods: Retrospectively collected data from a prospective database of consecutive patients with primary and metastatic brain tumors who received intra-arterial chemotherapy without osmotic blood-brain barrier disruption (IA) or intra-arterial chemotherapy with osmotic blood-brain barrier disruption (IA/OBBBD) at Oregon Health and Science University (OHSU) between December 1997 and November 2018 is reported. Chemotherapy-related complications are detailed per Common Terminology Criteria for Adverse Events (CTCAE) guidelines. Procedure-related complications are grouped as major and minor. Results: 4939 procedures (1102 IA; 3837 IA/OBBBD) were performed on 436 patients with various pathologies (primary central nervous system lymphoma [26.4%], glioblastoma [18.1%], and oligodendroglioma [14.7%]). Major procedure-related complications (IA: 12, 1%; IA/OBBBD: 27, 0.7%; P = .292) occurred in 39 procedures including 3 arterial dissections requiring intervention, 21 symptomatic strokes, 3 myocardial infarctions, 6 cervical cord injuries, and 6 deaths within 3 days. Minor procedure-related complications occurred in 330 procedures (IA: 41, 3.7%; IA/OBBBD: 289, 7.5%; P = .001). Chemotherapy-related complications with a CTCAE attribution and grade higher than 3 was seen in 359 (82.3%) patients. Conclusions: We provide safety and tolerability data from the largest cohort of consecutive patients who received IA or IA/OBBBD. Our data demonstrate that IA or IA/OBBBD safely enhance drug delivery to brain tumors and brain around the tumor.