title: Intraoperative electrocorticography for physiological research in movement disorders: principles and experience in 200 cases.
abstract: OBJECTIVE Contemporary theories of the pathophysiology of movement disorders emphasize abnormal oscillatory activity in basal ganglia-thalamocortical loops, but these have been studied in humans mainly using depth recordings. Recording from the surface of the cortex using electrocorticography (ECoG) provides a much higher amplitude signal than depth recordings, is less susceptible to deep brain stimulation (DBS) artifacts, and yields a surrogate measure of population spiking via "broadband gamma" (50-200 Hz) activity. Therefore, a technical approach to movement disorders surgery was developed that employs intraoperative ECoG as a research tool. METHODS One hundred eighty-eight patients undergoing DBS for the treatment of movement disorders were studied under an institutional review board-approved protocol. Through the standard bur hole exposure that is clinically indicated for DBS lead insertion, a strip electrode (6 or 28 contacts) was inserted to cover the primary motor or prefrontal cortical areas. Localization was confirmed by the reversal of the somatosensory evoked potential and intraoperative CT or 2D fluoroscopy. The ECoG potentials were recorded at rest and during a variety of tasks and analyzed offline in the frequency domain, focusing on activity between 3 and 200 Hz. Strips were removed prior to closure. Postoperative MRI was inspected for edema, signal change, or hematoma that could be related to the placement of the ECoG strip. RESULTS One hundred ninety-eight (99%) strips were successfully placed. Two ECoG placements were aborted due to resistance during the attempted passage of the electrode. Perioperative surgical complications occurred in 8 patients, including 5 hardware infections, 1 delayed chronic subdural hematoma requiring evacuation, 1 intraparenchymal hematoma, and 1 venous infarction distant from the site of the recording. None of these appeared to be directly related to the use of ECoG. CONCLUSIONS Intraoperative ECoG has long been used in neurosurgery for functional mapping and localization of seizure foci. As applied during DBS surgery, it has become an important research tool for understanding the brain networks in movement disorders and the mechanisms of therapeutic stimulation. In experienced hands, the technique appears to add minimal risk to surgery.
authors.affiliation: Department of Neurological Surgery, Mount Sinai School of Medicine, New York, New York.
authors.forename: Fedor
authors.initials: F
authors.lastname: Panov
authors.affiliation: Department of Neurological Surgery, University of Michigan, Ann Arbor, Michigan; and.
authors.forename: Emily
authors.initials: E
authors.lastname: Levin
authors.affiliation: Departments of 3 Neurological Surgery and.
authors.forename: Coralie
authors.initials: C
authors.lastname: de Hemptinne
authors.affiliation: Departments of 3 Neurological Surgery and.
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Swann
authors.affiliation: Departments of 3 Neurological Surgery and.
authors.forename: Salman
authors.initials: S
authors.lastname: Qasim
authors.affiliation: Departments of 3 Neurological Surgery and.
authors.forename: Svjetlana
authors.initials: S
authors.lastname: Miocinovic
authors.affiliation: Neurology, University of California, San Francisco, California.
authors.forename: Jill L
authors.initials: JL
authors.lastname: Ostrem
authors.affiliation: Departments of 3 Neurological Surgery and.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Starr
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D046690:Deep Brain Stimulation; D000069280:Electrocorticography; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring; D008875:Middle Aged; D009069:Movement Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D011183:Postoperative Complications; D016896:Treatment Outcome; D055815:Young Adult
keywords: DBS = deep brain stimulation; DLPFC = dorsolateral prefrontal cortex; ECoG = electrocorticography; FDA = Food and Drug Administration; LFP = local field potential; MER = microelectrode recording; PAC = phase-amplitude coupling; Parkinson's disease; brain oscillations; deep brain stimulation; electrocorticography; functional neurosurgery; movement disorders; primary motor cortex