Nerve fiber impairment of anterior thalamocortical circuitry in juvenile myoclonic epilepsy

BACKGROUND: Juvenile myoclonic epilepsy (JME) is a syndrome of idiopathic generalized epilepsy (IGE) without structural brain abnormalities detectable by MRI or CT.

OBJECTIVE: 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.

METHODS: 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").

RESULTS: 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.

CONCLUSIONS: 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.