A comparison of two fMRI methods for predicting verbal memory decline after left temporal lobectomy: language lateralization versus hippocampal activation asymmetry.
OBJECTIVE
Language lateralization measured by preoperative functional magnetic resonance imaging (fMRI) was shown recently to be predictive of verbal memory outcome in patients undergoing left anterior temporal lobe (L-ATL) resection. The aim of this study was to determine whether language lateralization or functional lateralization in the hippocampus is a better predictor of outcome in this setting.


METHODS
Thirty L-ATL patients underwent preoperative language fMRI, preoperative hippocampal fMRI using a scene encoding task, and pre- and postoperative neuropsychological testing. A group of 37 right ATL (R-ATL) surgery patients was included for comparison.


RESULTS
Verbal memory decline occurred in roughly half of the L-ATL patients. Preoperative language lateralization was correlated with postoperative verbal memory change. Hippocampal activation asymmetry was strongly related to side of seizure focus and to Wada memory asymmetry but was unrelated to verbal memory outcome.


CONCLUSIONS
Preoperative hippocampal activation asymmetry elicited by a scene encoding task is not predictive of verbal memory outcome. Risk of verbal memory decline is likely to be related to lateralization of material-specific verbal memory networks, which are more closely correlated with language lateralization than with overall asymmetry of episodic memory processes.
Binder
Jeffrey R
JR
Department of Neurology, Medical College of Wisconsin, 9200 W Wisconsin Ave., Milwaukee, WI 53226, USA. jbinder@mcw.edu
Swanson
Sara J
SJ
Sabsevitz
David S
DS
Hammeke
Thomas A
TA
Raghavan
Manoj
M
Mueller
Wade M
WM
D000328:Adult; D038481:Anterior Temporal Lobectomy; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D004833:Epilepsy, Temporal Lobe / Q000601:surgery*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology*; D011594:Psychometrics; D021641:Recognition, Psychology / Q000502:physiology; D012153:Retention, Psychology / Q000502:physiology; D013702:Temporal Lobe / Q000503:physiopathology; D014706:Verbal Learning / Q000502:physiology*