Electroencephalography in the Acute Phase of Stroke

Objective. To determine the frequency of nonconvulsive status epilepticus (NCSE), epileptiform activity, and rhythmic and periodic patterns in patients with acute cerebrovascular accidents (aCVA). Materials and methods. The informativeness of the EEG was studied in 86 patients hospitalized in the neurology section of the Department of Resuscitation and Intensive Therapy of a level 3 medical center with diagnoses of aCVA. The criterion for starting recordings was an epileptic seizure or clinical suspicion of NCSE. The content of biomarkers of the ictal-interictal continuum and the diagnostic value of the EEG were evaluated in relation to prognoses for survival and recovery of consciousness. Results. Pathological changes in the EEG were seen in 84% of patients. Most patients lacked a dominant occipital rhythm (DOR) (66% of patients) and many showed hemispheric slowing (42%). Slowing of the background rhythm to below the θ range was seen in 41% of patients. EEG reactivity was absent in 20% of patients. Individual epileptiform graphical elements were recorded in 36% of patients, while rhythmic and periodic patterns were recorded in 26%. Significant predictors of unfavorable outcomes were the absence of DOR, areactivity, and decreases in the amplitude and generalized slowing of the background EEG to below the θ range. Our data did not find any link between recording of epileptiform graphic elements or their rhythmic and periodic patterns on the one hand and an increased probability of death on the other. Conclusions. The most informative EEG indicators for prognosticating survival and recovery of consciousness were the amplitude, the dominant frequency of the background recording, and reactivity in response to external stimulation. Recording of sporadic epileptiform graphic elements and rhythmic and periodic patterns in patients with aCVA was not always linked with unfavorable prognoses. © 2021, Springer Science+Business Media, LLC, part of Springer Nature.