Transient global amnesia -- its clinical and pathophysiological basis and prognosis.

28 patients with transient global amnesia (TGA) were followed for a mean period of 73 months. The patients fell into 3 diagnostic groups: a group where patients had associated symptoms and signs of transient focal cerebral ischemia (TIA), a migraine group and a miscellaneous group. 22 patients had evidence of cerebrovascular disease or risk factors for cerebrovascular disease, and a vascular basis for the amnesic attack was highly suggestive in 25 patients. During the follow-up period 2 patients died, 3 had recurrent TGA and 13 developed a completed stroke or suffered from further TIA's. Permanent memory impairment was encountered in 9 cases. An unfavourable course was related to the presence of other TIA manifestations and/or risk factors for cerebrovascular disease. The study indicates that TGA is probably due to transient ischemia in the vertebrobasilar arterial distribution area. TGA per se has a good prognosis, but the coexistence of risk factor or manifest cerebrovascular disease implies a high rate of a subsequent completed stroke or permanent memory impairment.