Magnetic resonance imaging abnormalities in familial temporal lobe epilepsy with auditory auras

Two forms of familial temporal lobe epilepsy (FTLE) have been described: mesial FTLE and FTLE with auditory auras. The gene responsible for mesial FTLE has not been mapped yet, whereas mutations in the LGI1 (leucine-rich, glioma-inactivated 1) gene, localized on chromosome 10q, have been found in FTLE with auditory auras.

To describe magnetic resonance imaging (MRI) findings in patients with FTLE with auditory auras.

We performed detailed clinical and molecular studies as well as MRI evaluation (including volumetry) in all available individuals from one family, segregating FTLE from auditory auras.

We evaluated 18 of 23 possibly affected individuals, and 13 patients reported auditory auras. In one patient, auditory auras were associated with déjà vu; in one patient, with ictal aphasia; and in 2 patients, with visual misperception. Most patients were not taking medication at the time, although all of them reported sporadic auras. Two-point lod scores were positive for 7 genotyped markers on chromosome 10q, and a Zmax of 6.35 was achieved with marker D10S185 at a recombination fraction of 0.0. Nucleotide sequence analysis of the LGI1 gene showed a point mutation, VIIIS7(-2)A-G, in all affected individuals. Magnetic resonance imaging was performed in 22 individuals (7 asymptomatic, 4 of them carriers of the affected haplotype on chromosome 10q and the VIIIS7[-2]A-G mutation). Lateral temporal lobe malformations were identified by visual analysis in 10 individuals, 2 of them with global enlargement demonstrated by volumetry. Mildly reduced hippocampi were observed in 4 individuals.

In this family with FTLE with auditory auras, we found developmental abnormalities in the lateral cortex of the temporal lobes in 53% of the affected individuals. In contrast with mesial FTLE, none of the affected individuals had MRI evidence of hippocampal sclerosis.