Acute symptomatic seizures (ASyS) after stroke are the strongest predictor of post-stroke epilepsy (PSE). We investigated the use and findings of out-patient EEG among stroke patients with ASyS concerns.

ASyS and epileptiform abnormalities (EAs) after stroke are not uncommon in the age of continuous EEG (cEEG). Both significantly increase PSE risk. EEG remains a pivotal investigation tool in epilepsy diagnosis. However, its outpatient use in routine clinical care of stroke patients with high PSE risk remains poorly investigated.

After IRB approval, adults with acute stroke, ASyS concerns (underwent cEEG) and outpatient clinical follow-up between 04/01/2012 to 03/31/2018 were identified (study cohort). Patients with outpatient EEG (oEEG) after hospital discharge were analyzed for electrographic findings (EEG cohort). Descriptive statistical and univariate analyses were performed to identify variables that predicted oEEG in routine clinical care.

Among 507 study cohort patients, 102 (20.1%; 50% females) underwent oEEG. The EEG cohort was significantly (p <0.05) older, likely to have intracerebral hemorrhage and ischemic stroke with cortical involvement. EEG cohort was significantly more likely to have convulsive and electrographic ASyS [Odds Ratio (OR) = 5.13 (3.16 – 8.33)], EAs [OR = 3.09 (1.92 – 4.96)] in addition to anti-seizure medications at discharge [OR = 4.97 (3.11 – 7.92)]. Eight patients developed PSE during the follow-up, including 5 in the EEG cohort (OR = 6.91 (1.62 – 29.4)]. oEEG was performed a median of 9.3 (3.5 – 24.9) months after stroke with EAs in 9 (8.8%), and being normal in 26 (25.5%) patients. None of the PSE patients had EAs on oEEG.

1 in 5 patients with ASyS concern after stroke undergoes oEEG. These patients are significantly more likely to have risk factors for PSE. While close to 1 in 10 oEEGs show EAs, our small study suggests these do not seem to correlate with PSE.