RESUMEN
PURPOSE: Photosensitivity is a phenomenon that may be elicited by standardized intermittent photic stimulation during EEG recording and is detected more frequently in children and adolescents. Nevertheless, at our Epilepsy Center, we routinely assess photosensitivity in all newly referred adult patients. In this investigation, we sought to address the diagnostic yield under the prerequisites described. METHODS: We reanalyzed all routine EEG recordings among referrals to the department of adults during the first six months of 2019, including a simultaneous video that is always coregistered in our center. The prevalence of abnormal findings during photic stimulation was assessed. RESULTS: Intermittent photic stimulation was performed on 344 patients. Photoparoxysmal response were detected in five subjects (1.5%). All patients were female. Four patients were diagnosed with idiopathic generalized epilepsy, and one with Doose syndrome. Photomyogenic responses were recorded in 1.1% and only in patients with psychogenic nonepileptic seizures. In two subjects with psychogenic nonepileptic seizures, the typical seizure was provoked by intermittent photic stimulation (8.7% of all subjects with psychogenic nonepileptic seizures in this cohort). Photoparoxysmal response was not detected in any subject with focal epilepsy, syncope, or other nonepileptic paroxysmal events. In every case of photoparoxysmal responses, increased photosensitivity had already been reported before recording. CONCLUSIONS: In our study, photoparoxysmal responses was a rare phenomenon among adults with a preponderance of females and idiopathic generalized epilepsies. Intermittent photic stimulation may be helpful in provoking typical psychogenic nonepileptic seizures and thus abbreviate the diagnostic process. Provided a careful history, routine intermittent photic stimulation in adults with epilepsy does not appear to be mandatory.
RESUMEN
OBJECTIVE: Dopamine is an endogenous neuromodulator in cortical circuits and the basal ganglia. In animal models of temporal lobe epilepsy (TLE), seizure threshold is modulated to some extent by dopamine, with D1-receptors having a pro- and D2-receptors an anticonvulsant effect. We aimed to extend our previously reported results on decreased D2/D3 receptor binding in the lateral epileptogenic temporal lobe and to correlate them with demographic and seizure variables to gain a more comprehensive understanding of the underlying involvement of the dopaminergic system in the epileptogenesis of TLE. METHODS: To quantify D2/D3 receptor binding, we studied 21 patients with TLE and hippocampal sclerosis (13 left- and eight right-sided) and 18 controls using PET with the high-affinity dopamine D2/D3-receptor ligand 18F-Fallypride to image striatal and extrastriatal binding. TLE was defined by interictal and ictal video-EEG, MRI and 18F-Fluorodeoxyglucose PET. Voxel-based statistical and regions-of-interest analyses were performed. RESULTS: 18F-Fallypride binding potential was significantly reduced in the affected temporal lobe and bilateral putamen. A positive correlation between age at onset of epilepsy and [18F]FP BPnd (binding potential non-displaceable) in temporal regions on the epileptogenic side was found, as well as a negative correlation between epilepsy duration and [18F]FP BPnd in the temporal pole on the epileptogenic side and a positive correlation between the estimated number of lifetime GTCS and [18F]FP BPnd in the hippocampus on the epileptogenic side. SIGNIFICANCE: The areas of reduced D2/D3 receptor availability correspond to "the irritative zone" surrounding the epileptogenic area. Moreover, reduced D2/D3 receptor availability was detectable in the basal ganglia, which are suspected to be involved in a control circuit for epileptic seizures. The correlational analysis additionally suggests that increased epilepsy duration leads to increasing impairment of the dopaminergic system.
