Verbal memory outcome in patients with normal preoperative verbal memory and left mesial temporal sclerosis.
OBJECTIVE
Previous studies have shown that structural integrity (i.e., presence/absence of mesial temporal sclerosis (MTS)) of the left mesial temporal lobe is associated with verbal memory outcome following left anterior temporal lobectomy (ATL). However, the functional integrity of the left temporal lobe, as exemplified by preoperative verbal memory performance, has also been associated with verbal memory outcome following surgery. We investigated the risk of verbal memory loss in patients with known structural abnormality (i.e., left mesial temporal sclerosis by MRI) and normal preoperative verbal memory performance who undergo left ATL.


METHODS
Seventeen patients with left temporal lobe epilepsy, MRI-based exclusive left MTS, and normal preoperative verbal memory were identified. Normal verbal memory was defined as performance on both Acquisition (learning across trials 1-5) and Retrieval (long delayed free recall) portions of the California Verbal Learning Test (CVLT) above a T score of 40 (>16%ile). Postoperative verbal memory outcome was established by incorporating standardized regression-based (SRB) change scores.


RESULTS
Postoperative declines across both CVLT Retrieval T scores and Acquisition T scores (average 20% and average 15% declines from baseline scores, respectively) were measured for the group. The average CVLT Retrieval SRB change score was -2.5, and the average CVLT Acquisition SRB change score was -1.0. A larger proportion of patients demonstrated postoperative declines on Retrieval scores than Acquisition scores (64.7% vs 17.6%, respectively).


CONCLUSIONS
Even in the presence of left MTS, patients exhibiting normal presurgical verbal memory are at risk for verbal memory declines following ATL. These results suggest that the functional integrity of the left mesial temporal lobe may play an important role in the verbal memory outcome in this patient group.
LoGalbo
Anthony
A
Department of Neurology, Epilepsy Center, University of Alabama at Birmingham, Birmingham, AL, USA.
Sawrie
Stephen
S
Roth
David L
DL
Kuzniecky
Ruben
R
Knowlton
Robert
R
Faught
Edward
E
Martin
Roy
R
D000293:Adolescent; D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000379:methods; D003710:Demography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D012044:Regression Analysis; D016896:Treatment Outcome; D014706:Verbal Learning / Q000502:physiology*