Clinical and electroencephalographic characteristics of epilepsy following hypoxic-ischemic encephalopathy: a retrospective analysis

To characterize the clinical and electroencephalographic (EEG) features of epilepsy following hypoxic-ischemic encephalopathy (HIE) to better inform clinical diagnosis, therapeutic strategies, and prognostic assessment. A retrospective analysis was conducted on 25 patients diagnosed with epilepsy secondary to HIE. Data regarding patient demographics, seizure types, EEG findings, and treatment regimens were analyzed. Long-term prognosis was evaluated through a six-month follow-up. Myoclonic seizures were the most prevalent seizure type ( n = 12, 48%), followed by status epilepticus ( n = 5, 20%). Early-onset epilepsy was identified in 18 patients, 15 of whom (83.33%) presented with generalized seizures. Late-onset epilepsy was observed in 7 patients, including 3 cases (42.86%) of status epilepticus. A statistically significant difference in seizure phenotypes was observed between the early-onset and late-onset groups. EEG abnormalities were present in all 13 patients who underwent testing. Epileptiform discharges were detected in 7 patients (53.84%), while generalized persistent low voltage, diffuse slow waves, and focal slow waves were each observed in 2 patients (15.38%). Highly malignant EEG patterns were strongly associated with mortality. Regarding pharmacological intervention, 15 patients (60.00%) required combination anti-seizure medication (ASM) therapy, while 10 (40.00%) were managed with monotherapy. At the six-month follow-up, 2 patients (8%) experienced seizure recurrence, 9 (36%) achieved seizure freedom, and 14 (56%) had died. No significant differences were found in seizure type or medication efficacy across the different outcome groups. Myoclonic seizures represent the most common seizure manifestation in post-HIE Epilepsy. Epileptiform discharges are prevalent, with highly malignant EEG features serving as significant predictors of poor clinical outcomes. While combination ASM therapy is frequently necessary, the overall prognosis for epilepsy following HIE remains poor.