Electroencephalographic findings in acute subdural hematoma

The aim was to determine the electroencephalographic (or electroencephalogram [EEG]) findings predictive of functional outcome in a subset of patients with acute subdural hematoma (SDH) with epileptiform activity on their EEG. Twenty-four patients who underwent evacuation for acute or acute-on-chronic SDH and with epileptiform activity on EEG were identified retrospectively. Their EEGs were reviewed and the findings categorized along with clinical information, the preoperative computed tomography (CT) scan, and functional outcome. Twenty-one patients (87%) had epileptiform discharges on EEG; 13 of them (62%) had midline epileptiform discharges and 9 of them (43%) had periodic lateralized epileptiform discharges (PLEDs). Both types of epileptiform discharges were significantly associated with the degree of midline shift on neuroimaging (P = 0.01, P = 0.04, respectively). Poor early outcomes were associated with the presence of bilateral (P = 0.03), midline (P = 0.04), and bilateral independent multifocal discharges (P = 0.09) on EEG. The EEG findings in this group of patients were complex. Epileptiform discharges were common, and specific types were associated with midline shift on neuroimaging and poor functional outcome at hospital discharge. Improvement in follow-up EEG examinations over time was predictive of good long-term functional outcome.