Abstracts

RATIONALE: We examined the influence of multiple factors that are possible determinants of IQ and verbal memory to evaluate their relative contributions. Our main hypotheses were that the cumulative number of uncontrolled seizures, laterality, and seizure type are signifcant determinants of cognitive function.
METHODS: We identified 115 subjects who had undergone temporal lobectomy, and had medial temporal sclerosis on MRI and/or tissue pathology. Using multiple regression and MANOVA, we evaluated the relationship between factors such as age of onset, seizure lateraity, type of seizure, cumulative number of seizures, history of status epilepticus, handedness, and Beck Depression score on pre-operative Full Scale IQ (FSIQ)and Rey Auditory Verbal Learning Test (AVLT) scores.
RESULTS: Multiple regression with Full Scale IQ showed that only cumulative lifetime number of seizures correlated with FSIQ. None of the predictor variables accounted for a significant amount of the variance for the AVLT memory scores. A sub-analysis of the data showed that FSIQ and verbal memory scores were relatively stable until the cumulative lifetime seizures exceeded 7,000.
CONCLUSIONS: This study found that the cumulative number of lifetime seizures had a significant impact on Full Scale IQ scores, but not on measures of verbal memory. Scores were relatively unaffected by this variable until high levels of seizures were reached. These results provide some incentive for MTS patients with medically refractory seizures to opt for elective surgery sooner rather than later.