Left Inferior Temporal Hypometabolism Predicts Naming Errors
Abstract number :
K.04
Submission category :
Year :
2001
Submission ID :
2945
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
W.H. Theodore, MD, Clinical Epilepsy Section, NIH, Bethesda, MD; W.D. Gaillard, MD, Clinical Epilepsy Section, NIH, Bethesda, MD; K. Kelley, MA, Clinical Epilepsy Section, NIH, Bethesda, MD
RATIONALE: Patients with seizures arising from dominant temporal lobe foci often report relatively specific naming errors, which also can be elicited by basal temporal stimulation during electrocardiography. These errors may increase after basal temporal resections. However controversy exists over the importance of the basal temporal cortex for naming. Previous studies have shown increased cerebral blood flow during auditory responsive naming in this region, as well as impaired performance during cortical stimulation.
METHODS: We used positron emission tomography with 18F-2-deoxyglucose to study cerebral glucose metabolism, and its relation to neuropsychological test results in 83 patients with temporal lobe seizure foci localized on ictal video EEG). We measured cerebral metabolic rate for glucose (CMRglc), normalized to global metabolism, using a region of interest template. Neuropsychological tests including Boston Naming (BN), Verbal and visual Wechsler memory scales, verbal and performance intelligence quotients, Supermarket Fluency and California Verbal Learning Tests. Statistical Analysis was performed with Systat (SSPS inc).
RESULTS: Patients with left temporal foci had significantly lower left inferior lateral temporal (0.787 [plusminus] 0.083 versus 0.94 [plusminus] 0.078; p[lt]0.001), as well as mesial temporal (0.68 [plusminus] 0.065 versus .80 [plusminus] 0.065 (p[lt]0.001) hypometabolism. They had worse performance on the BN (percent correct 0.72 [plusminus] .136 versus 0.839 [plusminus] 0.107 p[lt]0.001). The inferior lateral but not mesial temporal asymmetry index (left-right / (0.5) (left + right) correlated significantly with performance on BN (R= 0.27; p[lt]0.04), but not with other neuropsychological measures. Measures of frontal metabolism were not related to naming.
CONCLUSIONS: Our results support previous studies showing the importance of left inferior or basolateral temporal cortex for naming. Dysfunction in this region may be related to the characteristic errors made by some patients with seizures originating in the temporal lobe. Mesial temporal and frontal hypometabolism are not related to naming errors.
Support: NIH NINDS Division of Intramural Research.