White matter quantitative anomalies and clinical outcome in drug-resistant epilepsies

We aimed to evaluate the relationship between cerebral white matter quantitative anomalies and postoperative clinical outcomes in patients with drug-resistant epilepsies.

Automatic fiber quantification methodology was used to determine the diffusional anomalies in cerebral white matter tracts, from eight patients with frontal lobe epilepsy (FLE) and 12 with temporal lobe epilepsy (TLE) candidates and/or undergoing epilepsy surgery. We studied the fractional anisotropy (FA), mean diffusivity (MD), volume (Vol), and number of fibers (Fib) of white matter tracts related to the physiopathologic mechanism of these epilepsies. The information was compared with that obtained from 19 healthy controls and between patients with seizure freedom and those with seizure recurrence 1 year after epilepsy surgery.

Significant pre- and postsurgical global and segmental abnormalities were characterized by increased MD and decreased FA, Vol, and Fib in tracts from both hemispheres. TLE patients with postsurgical seizure freedom had preoperative increased global MD of the contralateral inferior longitudinal fasciculus and uncinate fasciculus. Furthermore, drug-resistant epilepsy patients with seizure freedom had a presurgical segmental increased MD in the contralateral thalamic radiation. Additionally, FLE patients with seizure freedom exhibited postsurgical increases in the Fib of the ipsilateral thalamic radiation and contralateral inferior longitudinal fasciculus. Furthermore, temporal lobe epilepsy patients with seizure freedom had a postsurgical lower global MD in the ipsilateral inferior fronto-occipital fasciculus.

Patients with drug-resistant epilepsies have global and segmental quantitative white matter tract anomalies, which suggests cerebral neural involvement in this disease. These abnormalities can vary regarding the postsurgical clinical outcome.