Abstracts

Failure on memory tests in the intracarotid amobarbital procedure (IAP) ipsilateral to the side of proposed resection in patients with temporal lobe epilepsy is believed to identify patients at high risk for the development of severe postoperative amnesia after temporal resection. The validity of the IAP to predict severe postoperative decline in memory has been questioned. The purpose of the study was to assess the neuropsychological impact of temporal lobe surgery after failure on IAP memory tests., From databases at the Montreal Neurological Hospital, 27 patients were identified who had failed IAP memory tests after injection into the side of subsequent temporal lobe resection. Preoperative information collected included etiology, age at onset, and duration of epilepsy in addition to results of EEG, VEEG, MRI, neuropsychology and IAP. Surgical procedures performed and the extent of hippocampal resection were recorded. Postoperative neuropsychological assessment was completed a minimum of 3 months after surgery. Seizure outcome was classified according to Engel., Among the 27 patients, 18 had bilateral failure of the IAP and 9 had failed only from injection into the side of temporal lobe resection. Ten patients underwent invasive monitoring prior to resection. Seventeen patients underwent selective amygdalo-hippocampectomy (SAH) and 10 had cortico-amygdalo-hippocampectomy (CAH) with resection of 1.5-3.5 cm of hippocampus. Fifteen underwent operations on the left temporal lobe. Fifty-two per cent of patients were seizure free at last follow up. Verbal memory worsened in 50 % of patients, improved in 23 % and in 27 % there was no change. Visuoperceptual memory improved in 53 % of patients, declined in 29 % and was unchanged in 18 % of patients. One patient suffered a transient severe postoperative amnesia but subsequently recovered to his preoperative baseline status., Severe postoperative amnesia is a rare occurrence after temporal lobe surgery despite failure of preoperative intracarotid amobarbital memory tests and inclusion of medial temporal-lobe structures in the removal, but postoperative worsening of memory does occur in a certain proportion of cases. Nevertheless, in some cases there is an improvement and in others no change. Thus, a good outcome is possible in this population despite a high number of patients with preoperative evidence of bitemporal epilepsy.,