Changes in verbal and nonverbal memory following anterior temporal lobe surgery for refractory seizures: effects of sex and laterality

We studied the effects on verbal and nonverbal memory of anterior temporal lobe (ATL) surgery for epilepsy in 91 patients (46 men, 45 women), all of whom had left-hemisphere dominance for speech. Patients were divided into four groups according to sex and laterality of the excision. The memory tasks were administered shortly before surgery, 6 months postoperatively, and at a 2-year follow-up. Test scores were submitted to repeated-measures analyses of variance. We found that men treated with left temporal resection declined significantly in long-delay verbal memory after surgery, whereas no clear pre- to postoperative sex differences were found with respect to other verbal memory scores. Only the results on long-delay verbal memory confirm previous findings, showing a greater vulnerability of verbal memory to left ATL surgery in men than in women. Women with left temporal excisions obtained particularly poor scores on a long-delay nonverbal memory test preoperatively, but improved their performance on this test significantly after surgery. The seemingly gradual improvement during the 2-year follow-up suggests a plastic process.