Abstracts

Rationale: Photosensitivity can occur in several different epilepsy syndromes, the most frequent association being with genetic generalized epilepsy (GGE). Phenotypic overlap between the idiopathic photosensitive occipital epilepsy (IPOE) and GGE may occur. The coexistence of temporal lobe epilepsy (TLE) and GGE in the same patient is rarely reported. We describe the electro-clinical characteristics of a large family from Turkey with idiopathic photosensitive epilepsy (IPE) and a pedigree consistent with Mendelian inheritance. One individual had the unusual combination of TLE and IPE. Methods: A family with 6 affected individual over 2 generations had idiopathic epilepsy and both clinical and/or electrical photosensitivity on their EEGs. They underwent extensive electro-clinical phenotyping. Epilepsy syndromes were classified as IPOE, GGE and IPOE overlap, early onset photosensitive absence epilepsy (EOPAE), and TLE. Results: Four of the affected individuals with IPE were female. Age at seizure onset was between 3-15 years. Two affected family members had IPOE/ Juvenile absence epilepsy, one with IPOE/ Juvenile myoclonic epilepsy (JME), and 2 with EOPAE/IPOE. One individual had the coexistence of IPOE/JME and drug-resistant TLE with the left hippocampal sclerosis on MRI. She had a history of febrile seizure. Her interictal EEG recording showed generalized polyspike-and wave activity, photoparoxysmal response (PPR) related to eye closure and focal epileptiform discharges in the left anterior temporal region. Ictal EEG recording revealed ictal onset consisting of rhythmic 5 to 7 Hz activity in the left anterior temporal region. The left temporal lobe was hypometabolic on FDG-PET. TLE and IPOE/JME had a long parallel course before surgery. After surgery, she had no further focal seizures. 3 other individuals had febrile seizures only in this family.  Conclusions: The phenotyping in this family with IPE shows heterogeneous patterns of epilepsy syndromes with overlap between IPOE and GGEs. Although IPE subsyndromes may represent a biologic continuum, the coexistence of GGE and symptomatic TLE seems to be discrete entities and should not affect our decision for surgery. Funding: No funding