Mesial temporal lobe epilepsy with focal photoparoxysmal response

Abstract

ABSTRACT Intermittent photic stimulation (IPS) may produce epileptiform discharges and seizures, most of which are generalized. There are several cases of focal seizures of occipital origin induced by IPS and only five reported cases originating from the temporal lobe (TL). We report an unusual case of TL epilepsy, supported by electroclinical and neuroimaging data, with rhythmic focal TL discharges precipitated by photic stimulus. Case report: A 37 year old male with refractory epilepsy due to a right mesial temporal sclerosis presented a focal right TL photoparoxysmal response during IPS. A routine, interictal SPECT study obtained with injection of HMPAO, carried out during continuous pulses of the photic stimulus at 16 Hz, disclosed hyperperfusion over the right TL. Presurgical ictal studies demonstrated seizures arising from the same region. A temporal lobectomy rendered the patient seizure‐free and further EEGs with IPS were normal. Conclusion: To our knowledge, this is the sixth case in medical literature showing evidence of photosensitivity associated with a TL lesion and it is the first in which photic stimulation induced a focal electrographic response of the involved TL. We hypothesize that in rare cases, photosensitivity may be related to a mesial TL lesion without occipital cortex involvement.