Nerve fiber impairment of anterior thalamocortical circuitry in juvenile myoclonic epilepsy.

Abstract

Juvenile myoclonic epilepsy (JME) is a syndrome of idiopathic generalized epilepsy (IGE) without structural brain abnormalities detectable by MRI or CT. In the present study, we addressed the question of whether diffusion tensor MRI (DTI) can detect disease-specific white matter (WM) abnormalities in patients with JME. We performed whole head DTI at 3 T in 10 patients with JME, 8 age-matched patients with cryptogenic partial epilepsy (CPE), and 67 age-matched healthy volunteers. Nerve fiber integrity was compared between the groups on the basis of optimized voxel-by-voxel statistics of fractional anisotropy (FA) maps obtained by DTI (analysis of covariance, categorical factor "group," covariate "age"). FA was reduced in a WM region associated with the anterior thalamus and prefrontal cortex in patients with JME compared to both control subjects and patients with CPE (p < 0.001). The patients with CPE showed normal values in this particular WM region. The FA reductions in the patients with JME correlated with the frequency of generalized tonic-clonic seizures (Spearman R = 0.54, p = 0.05). No significant correlations were found in the JME sample between FA reduction and the duration of antiepileptic medication. The results support the hypothesis that juvenile myoclonic epilepsy is associated with abnormalities of the thalamocortical network that can be detected by diffusion tensor MRI.