The cognitive profile of occipital lobe epilepsy and the selective association of left temporal lobe hypometabolism with verbal memory impairment.
We investigated the cognitive profile of structural occipital lobe epilepsy (OLE) and whether verbal memory impairment is selectively associated with left temporal lobe hypometabolism on [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET). Nine patients with OLE, ages 8-29 years, completed presurgical neuropsychological assessment. Composite measures were calculated for intelligence quotient (IQ), speed, attention, verbal memory, nonverbal memory, and executive functioning. In addition, the Wisconsin Card Sorting Test (WCST) was used as a specific measure of frontal lobe functioning. Presurgical FDG-PET was analyzed with statistical parametric mapping in 8 patients relative to 16 healthy volunteers. Mild impairments were evident for IQ, speed, attention, and executive functioning. Four patients demonstrated moderate or severe verbal memory impairment. Temporal lobe hypometabolism was found in seven of eight patients. Poorer verbal memory was associated with left temporal lobe hypometabolism (p = 0.002), which was stronger (p = 0.03 and p = 0.005, respectively) than the association of left temporal lobe hypometabolism with executive functioning or with performance on the WCST. OLE is associated with widespread cognitive comorbidity, suggesting cortical dysfunction beyond the occipital lobe. Verbal memory impairment is selectively associated with left temporal lobe hypometabolism in OLE, supporting a link between neuropsychological dysfunction and remote hypometabolism in focal epilepsy.
Department of Psychology, Macquarie University, Sydney, New South Wales, Australia; Department of Medical Psychology, Westmead Hospital, Sydney, New South Wales, Australia.
Alex A
AA
Knopman
Chong H
CH
Wong
Richard J
RJ
Stevenson
Judi
J
Homewood
Armin
A
Mohamed
Ernest
E
Somerville
Stefan
S
Eberl
Lingfeng
L
Wen
Michael
M
Fulham
Andrew F
AF
Bleasel
D000328:Adult; D002648:Child; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology; D004828:Epilepsies, Partial / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology; D006801:Humans; D008569:Memory Disorders / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology; D049268:Positron-Emission Tomography / Q000379:methods; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism*
Focal epilepsy; Neuropsychological functioning; Occipital lobe epilepsy; Positron emission tomography; Surgical series