Concomitant fractional anisotropy and volumetric abnormalities in temporal lobe epilepsy: cross-sectional evidence for progressive neurologic injury

• Published in: PloS one Vol. 7; no. 10; p. e46791
• Main Authors: Keller, Simon S, Schoene-Bake, Jan-Christoph, Gerdes, Jan S, Weber, Bernd, Deppe, Michael
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 11.10.2012; Public Library of Science (PLoS)
• Subjects: Abnormalities; Adult; Anisotropy; Atrophy; Atrophy - complications; Biology; Brain; Brain - abnormalities; Brain research; Cognition & reasoning; Cognitive ability; Complications and side effects; Corpus callosum; Degeneration; Development and progression; Diffusion Tensor Imaging - methods; Epilepsy; Epilepsy, Temporal Lobe - complications; Epilepsy, Temporal Lobe - pathology; Female; Fibers; Hippocampus; Hippocampus - pathology; Humans; Hypoxia; Image Processing, Computer-Assisted; Imaging techniques; Linear Models; Magnetic resonance; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Medical imaging; Medicine; Memory; Middle Aged; Neurodegeneration; Neuroimaging; Neurology; Parahippocampal gyrus; Patients; Putamen; Risk factors; Sclerosis; Seizures; Seizures (Medicine); Studies; Substantia alba; Temporal lobe; Temporal Lobe - pathology; Temporal lobe epilepsy; Thalamus; Thalamus - pathology; Time Factors; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0046791

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). 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. 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.