Abstracts

RATIONALE: The sparse published research examining the relationship between IQ and memory performance on the intracarotid amytal perfusion test (IAP, or Wada's test) indicates that low IQ (< 80) may be associated with oversedation, but IQ generally does not correlate with IAP memory scores. A potential relationship between WAIS-R Full Scale IQ (FSIQ) and IAP memory scores may, however, be confounded by interactions between the large verbal component of FSIQ, side of injection, and side of seizure onset. METHODS: Subjects were 16 patients with left temporal lobe seizure onset (LSO), and 20 with right temporal lobe seizure onset (RSO). Subjects were divided into low (IQLOW, FSIQ < 80) or normal FSIQ (IQWNL) groups. All subjects underwent IAP and neuropsychological testing. Three 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, with a .5 penalty for false alarms. RESULTS: The RSO and LSO groups did not differ on FSIQ. IAP memory scores did not differ between IQLOW and IQWNL groups on contralateral injection. However, there was a significant interaction between side of seizure onset and IQ level on ipsilateral injection memory scores (F(1,32)=4.15, p < .05). For the LSO patients, there was no difference between memory scores for IQLOW and IQWNL subjects. However, RSO IQLOW patients scored significantly worse than RSO IQWNL patients (F(1,18)=6.49, p < .05), and for RSO subjects FSIQ and ipsilateral injection memory scores were correlated .44 (p=.054). CONCLUSIONS: FSIQ and IAP memory scores are related. Low IQ is associated with worse IAP memory performance in RSO patients on ipsilateral amytal injection. Patients with low FSIQ and RSO may be more likely to be identified as IAP failures. FSIQ and IAP memory could also be related in LSO patients and on contralateral injection, but the effect may be confounded by the pathology underlying the seizure focus and the large verbal component of FSIQ. Replication with patients having right language dominance and less verbally loaded measures of general cognitive functioning is needed.