Electrographic seizures and periodic discharges after intracerebral hemorrhage

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Abstract
Objective: To determine the frequency and significance of electrographic seizures and other EEG findings in patients with intracerebral hemorrhage (ICH). Methods: We reviewed 102 consecutive patients with ICH who underwent continuous electroencephalographic monitoring (cEEG). Demographic, clinical, radiographic, and cEEG findings were recorded. Using multivariate logistic regression analysis, we determined factors associated with 1) electrographic seizures, 2) periodic epileptiform discharges (PEDs), and 3) poor outcome (death, vegetative or minimally conscious state) at hospital discharge. Results: Seizures occurred in 31% (n = 32) of patients with ICH, prior to cEEG in 19 patients. Eighteen percent (n = 18) of patients had electrographic seizures; only one of these patients also had clinical seizures while on cEEG. After controlling for demographic and clinical predictors, only an increase in ICH volume of 30% or more between admission and 24-hour follow-up CT scan was associated with electrographic seizures (33% vs 15%; OR 9.5, 95% CI 1.7 to 53.8). PEDs were less frequently seen in those with hemorrhages located at least 1 mm from the cortex (8% vs 29%; OR 0.2, 95% CI 0.1 to 0.7). PEDs were independently associated with poor outcome (65% vs 17%; OR 7.6, 95% CI 2.1 to 27.3). In patients with electrographic seizures, the first seizure was detected within the first hour of cEEG monitoring in 56% and within 48 hours in 94%. Conclusions: Seizures occurred in one third of patients with intracerebral hemorrhage (ICH) and over half were purely electrographic. Electrographic seizures were associated with expanding hemorrhages, and periodic discharges with cortical ICH and poor outcome. Further research is needed to determine if treating or preventing seizures or PEDs might lead to improved outcome after ICH. GLOSSARY: BIPLEDs = bilateral independent PLEDs; cEEG = continuous EEG monitoring; CLUES = clinically unrecognized electrographic seizures; EVD = external ventricular drain; IRDA = frontal intermittent rhythmic delta activity; GCS = Glasgow Coma Score; GOS = Glasgow Outcome Scale; GPDs = generalized periodic discharges; ICH = intracerebral hemorrhage; ICP = intracranial pressure; ICU = intensive care unit; IVH = intraventricular hemorrhage; NICU = neuroICU; PEDs = periodic epileptiform discharges; PLEDs = periodic lateralized epileptiform discharges; SAH = subarachnoid hemorrhage; SDH = subdural hematomas; SE = status epilepticus; SIRPIDS = stimulus-induced rhythmic, periodic, or ictal discharges.