Neuroanatomical correlates of cognitive phenotypes in temporal lobe epilepsy.

OBJECTIVE

Previous research characterized three cognitive phenotypes in temporal lobe epilepsy, each associated with a different profile of clinical seizure and demographic characteristics, total cerebral (gray, white, cerebrospinal fluid) and hippocampal volumes, and prospective cognitive trajectories. The objective of this investigation was to characterize in detail the specific neuroanatomical abnormalities associated with each cognitive phenotype.

METHODS

High-resolution MRI scans of healthy controls (n=53) and patients with temporal lobe epilepsy (n=55), grouped by cognitive phenotype (minimally impaired; memory impaired; memory, executive function, and speed impaired), were examined with respect to patterns of gray matter thickness throughout the cortical mantle, as well as volumes of subcortical structures, corpus callosum, and regions of the cerebellum.

RESULTS

Increasing abnormalities in temporal and extratemporal cortical thickness, volumes of subcortical structures (hippocampus, thalamus, basal ganglia), all regions of the corpus callosum, and bilateral cerebellar gray matter distinguish the cognitive phenotypes in a generally stepwise fashion. The most intact anatomy is observed in the minimally impaired epilepsy group and the most abnormal anatomy is evident in the epilepsy group with impairments in memory, executive function, and speed.

CONCLUSION

Empirically derived cognitive phenotypes are associated with the presence, severity, and distribution of anatomic abnormalities in widely distributed cortical, subcortical, callosal, and cerebellar networks.