Transient global amnesia: pathogenesis and prognosis.

Fifty-five patients admitted to hospital for 'pure' transient global amnesia (TGA) were studied and followed up for a period ranging from 12 to 67 months. The major pathogenetic theories of TGA (epileptic, thrombotic and migrainous) were investigated through the study of clinical histories and risk factors and the recurrences of neurological disturbances during follow-up. Seventy-one percent of the sample had one or more thrombotic risk factors (TRF), 2 patients had both TRF and a history of migraine, and none ever experienced a seizure. A computerized tomography (CT) scan was performed in 40 out of 55 patients to detect focal lesions: 3 patients (7.5%) had a lacuna in the deep structures of the brain. Over the follow-up period, 1 patient died from hepatic cirrhosis, 1 patient died from cerebral haemorrhage, 2 patients experienced transient ischaemic attacks and 3 patients had a total of 4 TGA recurrences. Our conclusion is that TGA represents a benign form of transient ischaemic cerebral disease.