Abstracts

Posterior Communicating Artery Wada for memory evaluation is rarely done. The presurgical internal carotid artery Wada for memory evaluation provides sufficient information in many patients with medically intractable epilepsy. We report five cases in which performance of posterior communicating artery Wada helped us evaluate the hippocampus involvement in memory function, after the Internal Carotid Artery WADA injection demonstrated that patients may be at risk for memory loss if mesiotemporal structures would be removed. In the five patients bilateral internal carotid artery injection of amobarbital was performed with concurrent EEG recording. Subsequently patients had language and memory evaluation done by Neuropsycology team. The evaluation of memory function suggested bihemispheric memory representation, with the concern that the patients may experience memory decline after ipsilateral resection of mesiotemporal structures.Additional testing with amobarbital injected in the ipsilateral posterior communicating artery supplying the hippocampus was done, with additional small amounts of amobarbital being needed until patient developed a visual field cut. Clinically, patients were evaluated for development of homonymous hemianopsia which suggests adequate posterior communicating artery injection. In all of the cases the concurrent EEG recording showed minimal background slowing of the hemisphere being injected. Additional memory testing was performed and demonstrated good memory support in the remaining hemisphere not supplied by PCA and in the contralateral hemisphere therefore allowing safe resection of the tested hippocampus. Post-surgical follow up with Neuropsychological testing did not demonstrate any memory impairment. Inconclusive bilateral carotid Wada testing does not disqualify the patients with intractable epilepsy from being a good candidate for surgical resection of mesiotemporal structures. Posterior communicating artery Wada is very useful in assessing involvement of hippocampus in memory function .