Hippocampal formation involvement in a language-activation task in patients with mesial temporal lobe epilepsy.
OBJECTIVE
The study aims to explore the contribution of the hippocampal formation to the retained language-comprehension network in patients with unilateral mesial temporal lobe epilepsy (TLE).


METHODS
We performed a functional magnetic resonance (MRI) study based on a language comprehension paradigm in 45 right-handed patients with unilateral mesial TLE and 35 healthy control subjects. Activations in the hippocampal formations in both hemispheres were analyzed for each subject as well as for groups of left TLE, right TLE, and controls.


RESULTS
In sum, 82% of TLE patients displayed hippocampal activations. A significant difference in hippocampal activation between left and right TLE was found: Right TLE patients showed increased activity in the left hippocampal formation compared with left TLE patients. In contrast, patients with left TLE did not show increased activity in the right hippocampal formation compared with right TLE patients. In comparison with a healthy control group, right TLE patients activated the left hippocampal formation to a greater extent, whereas patients with left TLE did not activate the right hippocampal formation to a greater degree. These findings point to an increased involvement of the left hippocampal formation during a language-comprehension task in right TLE patients. In contrast, left TLE in right-handed patients seems not associated with an enhanced involvement of the right hippocampal formation in retained language comprehension.


CONCLUSIONS
These findings suggest that effective language comprehension in right-handed subjects with TLE depends on the involvement of the left hippocampal formation and underline the risks of postoperative language decline in patients with left TLE.
Bartha
Lisa
L
Clinical Department of Neurology, Innsbruck Medical University, Insbruck, Austria.
Mariën
Peter
P
Brenneis
Christian
C
Trieb
Thomas
T
Kremser
Christian
C
Ortler
Martin
M
Walser
Gerald
G
Dobesberger
Judith
J
Embacher
Norbert
N
Gotwald
Thaddäus
T
Karner
Elfriede
E
Köylü
Buelent
B
Bauer
Gerhard
G
Trinka
Eugen
E
Benke
Thomas
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology* / Q000503:physiopathology*; D006801:Humans; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012660:Semantics; D013702:Temporal Lobe / Q000503:physiopathology