Abstracts

RATIONALE: Anecdotal evidence suggests that false positive errors (FPE) on intracarotid amytal perfusion (IAP) memory testing are fairly common, and most clinicians routinely correct IAP recognition memory scores for FPE. However, IAP FPE have received scant attention from researchers. The purpose of this study was to determine the prevalence and correlates of FPE on IAP recognition memory testing in patients with TLE.
METHODS: Subjects were 33 patients with left temporal lobe seizure onset (LSO), and 22 with right temporal lobe seizure onset (RSO). All subjects underwent IAP and neuropsychological testing. Seven subjects had bilateral representation of speech; the rest were left language dominant. IAP memory was tested with recognition of 9 objects presented with 18 foils. The FPE measures of interest were total FPE (TFPE), and FPE on ipsilateral (IFPE) and contralateral (CFPR) injections to the side of seizure onset. Correlations were calculated for TFPE, IFPE, and CFPE with WAIS-R IQ scores, measures from the Benton Multilingual Aphasia examination, California Verbal Learning Test (CVLT), Trail Making Test, Wisconsin Card Sort Test, and Minnesota Multiphasic Personality Inventory-2 (MMPI-2).
RESULTS: Seventy-eight percent of subjects made at least one FPE. Of these, most made 1-3 FPE (54%). Relatively few subjects made 4+ FPE (24%), and only 5% made 10 or more FPE. For subjects who made FPE, 86% of subjects made CFPE, whereas 49% made IFPE, indicating that the former is more likely to occur. However, CFPE and IFPE were correlated ([italic]r[/italic] = .29, [italic]p[/italic] [lt] .05) overall. For LSO patients, IFPE were related to performance on CVLT trial 1-5 recall ([italic]r[/italic] = -.51, [italic]p[/italic] [lt] .01), FPE ([italic]r[/italic] = .43, [italic]p[/italic] [lt] .05), and discriminability ([italic]r[/italic] = -.54, [italic] p [/italic][lt] .01). For RSO patients, IFPE were not related to personality or cognitive measures. However, CFPE were related to MMPI-II scale 4 ([italic]r[/italic] = .68, [italic]p[/italic] [lt] .01), 6 ([italic]r[/italic] = .59, [italic]p[/italic] [lt] .05), 8 ([italic]r[/italic] = .64, [italic]p[/italic] [lt] .05), and 9 ([italic]r[/italic] = .67, [italic]p[/italic] [lt] .01) elevations.
CONCLUSIONS: FPE were fairly common on IAP memory testing, although the majority of subjects made 4 or fewer errors. FPE were somewhat more common on contralateral injection, but ipsi- and contralateral injection FPE were correlated, suggesting that subjects who made FPE tended to do so on both injections. For LSO patients, IAP FPE were associated with verbal memory performance and FPE on the CVLT. This was not the case for RSO patients. IAP FPE for RSO patients were associated with scores on MMPI-2 clinical scales. FPE on IAP testing is not simply random or context specific, and is related to cognitive and personality features of patients.