Asymmetry of long-latency auditory evoked potentials in LGI1-related autosomal dominant lateral temporal lobe epilepsy

Purpose: To investigate auditory processing with cortical long-latency auditory evoked potentials (AEPs) in patients with autosomal dominant lateral temporal lobe epilepsy (ADTLE). Methods: Eight patients with LGI1-related ADTLE belonging to a family with predominantly aphasic seizures were studied. Sixty-five individuals without epilepsy served as controls. AEPs (N1-P2 amplitudes) to binaural tones were recorded over the left and the right hemispheres. Brainstem auditory evoked potentials (BAEPs) to monaural rarefaction clicks also were analyzed. Group differences were statistically assessed with Student's t test and repeated-measures analysis of variance. Results: Left N1-P2 AEP amplitudes were moderately reduced in ADTLE patients (p = 0.005). No group differences in BAEP were found, indicating unaffected cochlear system and auditory brainstem pathways. Conclusions: A moderate, but highly significant reduction in N1-P2 AEP amplitudes over the left hemisphere was demonstrated in patients with ADTLE. This finding corresponds to the cardinal symptom of aphasia in this family, and also to the generally prevailing left-sided EEG abnormalities in this condition. The background for this electrophysiologic lateralization in LGI1-related epilepsy is unknown. It may be related to a specific function of LGI1 in the dominant hemisphere.