Victoria Symptom Validity Test Performance in Non-Litigating Epilepsy Surgery Candidates

Abstract

We report Victoria Symptom Validity Test (VSVT) performance in 120 epilepsy patients undergoing neuropsychological assessment as part of their evaluation as epilepsy surgery candidates. Patients were grouped according to their performance on hard VSVT stimuli. Scores of at least 21/24 on the hard VSVT items were classified as valid (n=86), scores of 18/24–20/24 were considered questionably valid (n=20), and scores of 17/24 and below were designated as invalid (n=14). Significant group effects were observed for WAIS-III Full Scale IQ, Verbal IQ, Performance IQ, Digit Span, Rey 3x5 Memory, Selective Reminding Recognition, and Complex Figure Immediate Recall; poorer cognitive scores were associated with lower VSVT scores. Age was also related to VSVT performance, with patients older that 40 years of age (16/42) more likely to fail the VSVT (i.e., hard scores ≤ 20/24) than their younger counterparts (8/78) (p=.0006, Fisher's Exact Test). These results indicate that VSVT may identify cases of incomplete effort in patients being evaluated for strictly clinical purposes in which no external incentive to perform poorly has been identified, although the potential confound of low IQ on VSVT cannot be determined from this sample. Older patients also appear to be at increased risk for suboptimal performance, and may need additional encouragement or education regarding the need to perform to the best of their ability, and thereby maximize the likelihood of obtaining valid neuropsychological test results.