The new Maudsley series of temporal lobectomy. I: Short-term cognitive effects.

Cognitive effects of temporal lobectomy for the relief of focal seizures were examined in 59 adult cases (29 left and 30 right). Verbal and non-verbal intelligence and memory were tested pre-operatively and four weeks post-operatively. Slight, non-significant differences between left and right cases pre-operatively were added to by slight, non-significant differences in change across the operation, to produce some significant post-operative differences--right cases being significantly higher on verbal IQ and lower on non-verbal IQ, for example. Variation in cognitive outcome was related to certain subject variables. Those who showed no deterioration or more improvement across the operation tended to be younger, less intellectually able pre-operatively, had an earlier first seizure and an earlier onset of regular seizures. The implications of these results for a model of the effects of temporal lobectomy are discussed.