Concomitant fractional anisotropy and volumetric abnormalities in temporal lobe epilepsy: cross-sectional evidence for progressive neurologic injury.
BACKGROUND
In patients with temporal lobe epilepsy and associated hippocampal sclerosis (TLEhs) there are brain abnormalities extending beyond the presumed epileptogenic zone as revealed separately in conventional magnetic resonance imaging (MRI) and MR diffusion tensor imaging (DTI) studies. However, little is known about the relation between macroscopic atrophy (revealed by volumetric MRI) and microstructural degeneration (inferred by DTI).


RESULTS
For 62 patients with unilateral TLEhs and 68 healthy controls, we determined volumes and mean fractional anisotropy (FA) of ipsilateral and contralateral brain structures from T1-weighted and DTI data, respectively. We report significant volume atrophy and FA alterations of temporal lobe, subcortical and callosal regions, which were more diffuse and bilateral in patients with left TLEhs relative to right TLEhs. We observed significant relationships between volume loss and mean FA, particularly of the thalamus and putamen bilaterally. When corrected for age, duration of epilepsy was significantly correlated with FA loss of an anatomically plausible route - including ipsilateral parahippocampal gyrus and temporal lobe white matter, the thalamus bilaterally, and posterior regions of the corpus callosum that contain temporal lobe fibres - that may be suggestive of progressive brain degeneration in response to recurrent seizures.


CONCLUSIONS
Chronic TLEhs is associated with interrelated DTI-derived and volume-derived brain degenerative abnormalities that are influenced by the duration of the disorder and the side of seizure onset. This work confirms previously contradictory findings by employing multi-modal imaging techniques in parallel in a large sample of patients.
Department of Neurology, University of Münster, Münster, Germany ; Department of Clinical Neuroscience, Institute of Psychiatry, King's College London, London, United Kingdom.
Simon S
SS
Keller
Jan-Christoph
JC
Schoene-Bake
Jan S
JS
Gerdes
Bernd
B
Weber
Michael
M
Deppe
D000328:Adult; D016880:Anisotropy; D001284:Atrophy / Q000150:complications; D001921:Brain / Q000002:abnormalities*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000150:complications / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013702:Temporal Lobe / Q000473:pathology; D013788:Thalamus / Q000473:pathology; D013997:Time Factors