Selective posterior cerebral artery amobarbital test in patients with temporal lobe epilepsy for surgical treatment

PURPOSE To evaluate whether the selective posterior cerebral artery amobarbital test (PCAAT) can predict postoperative memory function in patients with temporal lobe epilepsy (TLE) for surgical treatment and its clinical safety. METHODS The database included adult patients with intractable TLE undergoing presurgical evaluation at Taipei Veterans General Hospital between 1995 and 2002. The PCAAT was carried out on patients who had failed conventional intracarotid amobarbital test (IAT) or had IAT results that evoked a concern of postoperative memory function decline. A battery of learning and memory testing was performed immediately before and after injection of amobarbital into the peduncular segment of the posterior cerebral artery (PCA) on the presumed hemisphere of epileptogenicity. Neuropsychological assessments were followed in surgically treated patients. RESULTS A total of 16 patients completed PCAAT successfully and underwent anterior temporal lobectomy (ATL). Four patients failed PCAAT angiographic procedures due to technical difficulty in one patient, transient signs of vasospasm in two patients, and subarachnoid hemorrhage in one patient. Of the 12 patients who performed well in PCAAT learning and memory testing items by free recall or recognition, only 1 patient demonstrated postoperative memory decline in follow-up neuropsychological assessments. In contrast, two of the four patients with a deficit in PCAAT memory testing showed postoperative memory decline. Regarding subjective memory function (not necessarily associated with objective memory decline), patients not seizure-free after ATL were more likely to have memory complaints (in 3 out of 6 patients) than patients with seizure-free outcomes (in 1 out of 10 patients). CONCLUSIONS The PCAAT memory test reliably predicts postoperative memory function in patients with TLE for surgical treatment. However, the inherent risks of PCAAT must be considered and it should be used judiciously.