Antiseizure Medication Withdrawal, Risk of Epilepsy, and Longterm EEG Trends in Acute Symptomatic Seizures or Epileptic EEG Patterns.

Background and objectives: Patients with acute symptomatic seizures (ASyS) and acute epileptiform findings on EEG are common. They are often prescribed long-term antiseizure medications (ASMs); it is unknown whether or when this is necessary. Primary outcome was late unprovoked seizure occurrence and association with ASM taper. The secondary outcome was EEG pattern evolution over time.

Methods: This is a retrospective cohort study of patients from 2015 to 2021 with ASyS (clinical or electrographic) and/or epileptiform findings on index hospitalization EEGs who were discharged on ASMs and had subsequent follow-up including an outpatient EEG at Yale New Haven Hospital. All patients were seen in our postacute symptomatic seizure (PASS) clinic after hospital discharge. We also developed a simple predictive score, Epilepsy-PASS (EPI-PASS), using variables independently associated with seizure recurrence based on stepwise regression; each of the 3 identified variables was assigned a score of 0 (absent) or 1 (present), for a total score of 0-3.

Results: Of 190 patients screened, 58 were excluded, leaving a final cohort of 112 patients. Twenty-four percent (27/112) patients developed a late unprovoked seizure (i.e., epilepsy). Independent predictors of epilepsy were persistence of epileptiform abnormalities on follow-up EEGs [56% developed epilepsy vs 19% without, 0.002, OR 7.18 (1.36-37.88)], clinical ASyS [32% vs 13%, p = 0.002, OR 7.45 (2.31-54.36)], and cortical involvement on imaging [40% vs 11%, p = 0.003, OR 7.63 (1.96-29.58)]. None of the 23 patients with none of these predictors (0 points on EPI-PASS) developed epilepsy, vs 13% with 1 predictor (EPI-PASS = 1) and 46% with 2 or 3 predictors (EPI-PASS = 2-3) at 1-year follow-up. ASM taper was not associated with seizure recurrence. Abnormal EEG findings in the index hospitalization usually resolved [54/69 (78%) patients] on subsequent EEGs.

Discussion: Most patients with clinical ASyS or acute epileptiform EEG findings do not require long-term ASMs. Index hospitalization EEG findings usually resolve, but if they do not, there is a >50% chance of developing epilepsy. Other predictors of epilepsy are cortical involvement on imaging and clinical ASyS. A simple 4-point scale using these 3 predictors (EPI-PASS) may help predict the risk of developing epilepsy but requires independent validation.