Post-stroke epilepsy: Clinical and electrophysiological features

Abstract

Stroke is a common cause of new-onset seizures after middle age and the leading cause of symptomatic epilepsy in elderly, and causes 22–30% of adult status epilepticus cases. The International League Against Epilepsy differentiates between early (within seven days post-stroke) and late seizures. Majority of early seizures occurred within the first 24 hours. Early age at first stroke, haemorrhagic and cardio-embolic stroke, anterior circulation infarction, cortical and subcortical involvement are known risk factors for seizures and post-stroke epilepsy. Around 25% of patients with post-stroke epilepsy become drug resistant. Patients with seizures showed EEG abnormalities: diffuse or focal slowing, sharp waves, focal spikes, spikes and waves or periodic lateralized epileptic discharges (PLEDs). We report a paradigmatic case of a 59-year-old female, admitted for a confusion and memory deficit. MRI revealed a left temporo-occipital lesion, showing imaging features of a high-grade glioma. Surgery was complicated by middle cerebral artery vasospasm. She presented a brachial motor deficit and fluctuant trouble behaviour. The first EEG showed bi-PLEDs, broader and associated to rhythmic discharges (PLEDs plus) over the left carrefour derivations. Furthermore, we record seven non-convulsive seizures (NCs). Ictal EEG pattern was characterized by quasiperiodic sharp waves followed by rhythmic sharp theta activity over left posterior derivations. After receiving antiepileptic drug treatment she recovered to admission baseline, any further seizure was recorded and PLEDs progressively disappeared over the right hemisphere. PLEDs are more frequent in patients with early-onset seizures. PLEDs plus have been correlated with forthcoming seizures. In stroke patients with unexplained consciousness or trouble behaviour, cEEG may allow to diagnose NCs. Likelihood of recurrent seizures doubled when PLEDs are associated to NCs in acute phase post-stroke.