A case-control study of transient global amnesia.

To evaluate risk factors and prognosis of transient global amnesia (TGA), three groups of 30 subjects each affected respectively by: (1) first-ever TGA; (2) first-ever transient ischaemic attack (TIA); (3) depressive neurosis, were compared. Prevalence of cerebrovascular risk factors was similar in patients with TGA and TIA, but significantly lower in the third group. CT showed more hypodense lesions in TIA patients than in those with TGA. In a mean follow-up of 36 months, five TGA patients experienced a TIA and three others had recurrence of TGA, but none suffered stroke or myocardial infarction. In the TIA group, four had recurrence of TIA, two suffered a stroke and two others a myocardial infarction, whereas none had TGA attacks. None of the patients of the third group had any ischaemic event during follow-up. The similar prevalence of risk factors, but the different prognosis between TGA and TIA patients, suggest that TGA is an ischaemic event, probably not triggered by thromboembolism but by a different, possibly vasospastic, mechanism.