Photosensitive occipital lobe epilepsy: Delineation of an under‐recognized reflex epilepsy syndrome according to the new ILAE criteria and long‐term follow‐up

Abstract

AbstractObjectivePhotosensitive occipital lobe epilepsy (POLE) should be suspected in patients with occipital lobe seizures triggered by photic stimuli, who have normal motor‐mental development and brain imaging. We aimed to examine the clinical, electrophysiological, and prognostic features of POLE, which is a rare and under‐investigated syndrome.MethodsArchives from two tertiary epilepsy centers were retrospectively scanned and patients with normal neurological examination and cranial imaging were identified with POLE if they had: (1) seizures consistently triggered by photic stimuli; (2) non‐motor seizures with visual symptoms; and (3) photosensitivity documented on EEG. The clinical and electrophysiological features and prognostic factors were evaluated for patients who had follow‐up ≥5 years.ResultsWe identified 29 patients diagnosed with POLE with a mean age of 20.1 ± 7.6 years. In one‐third of the patients, POLE syndrome overlapped with genetic generalized epilepsy (GGE). The overlap group had higher rates of febrile seizure history and self‐induction; when compared to pure POLE patients, their EEGs showed more frequent interictal generalized epileptic discharges and posterior multiple spikes during intermittent photic stimulation. During long‐term follow‐up, the remission rate for POLE was 80%, but EEG photosensitivity persisted in three quarters of patients despite clinical remission, and more than half had relapsed after clinical remission.SignificanceThis first long‐term follow‐up study, utilizing newly suggested criteria of the International League Against Epilepsy, showed that POLE syndrome shows a notable overlap with GGE but also has distinctive features. POLE has a good prognosis; however, relapses are common, and photosensitivity persists as an EEG finding in the majority of patients.