Evaluation of cerebral white-matter micro-structural alterations in patients with medically refractory epilepsy using diffusion tensor tractography.
BACKGROUND
Diffusion tensor tractography (DTT) is a newer magnetic resonance imaging (MRI) technique that helps in evaluation of white matter. Presurgical planning with tractography may be valuable for evaluation of white matter tracts and their relationship with epileptogenic focus and for evaluation of cortical fibres around the epileptogenic zone.


METHODS
This study was carried out on 33 patients diagnosed with medically refractory epilepsy (males, 27; females, 6) with a mean age of 31.93 (range: 19-50) years. Twenty age and sex matched controls were also included. DTT evaluation was done using a 3.0 TexlaMRI scanner. Single-shot spin-echo echo-planar imaging (with 32-different diffusion gradient directions) was acquired for reconstruction of the white matter tracts. Diffusion metrics within fibre bundles that were reconstructed by a continuous fibre-track algorithm were compared between groups.


RESULTS
Patients had either partial seizures (21 patients; simple partial, complex partial or secondarily generalized seizure) or generalized seizures (12 patients; tonic clonic, tonic or myoclonic). Out of the 33 patients, 23 patients were classified into the lesional group and the rest into the non-lesional group. The lesions observed on conventional MRI included focal gliosis, hippocampal sclerosis, post-hypoxic encephalopathy, calcification and post-traumatic cavitation, in various parts of the brain. Significant differences were observed in terms of fractional anisotropy and mean diffusivity values amongst controls and patients, as well as on the lesional and non-lesional side of the brain; patients with a normal conventional imaging showed fractional anisotropy and mean diffusivity changes as well.


CONCLUSIONS
We conclude that widespread diffusion abnormalities occur in the white matter tracts on the side of lesion as well as distant from the epileptic focus.
Department of Neurology, King George Medical University, Lucknow, Uttar Pradesh, India.
Prakash
P
Kori
Ravindra Kumar
RK
Garg
Hardeep Singh
HS
Malhotra
Rakesh Kumar
RK
Gupta
Rajesh
R
Verma
Maneesh Kumar
MK
Singh
Ram Kishore Singh
RK
Rathore
Pradeep Kumar
PK
Gupta
D000328:Adult; D001921:Brain / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D004827:Epilepsy / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*
Diffusion tensor imaging; Diffusion tensor tractography; Epilepsy surgery; Magnetic resonance imaging; Medically refractory epilepsy