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%, = 0.002, OR 7.45 (2.31-54.36)], and cortical involvement on imaging [40% vs 11%, = 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.