[Transient global amnesia. Case-control study of 24 cases]

Transient global amnesia (AGT) is a well-defined syndrome of unknown aetiology. It is generally believed to be of vascular origin. Other theories suggest epilepsy or migraine as the cause. We studied the clinical features and associated risk factors in 24 patients with AGT, comparing them with two control groups with 24 people in each group, paired for age and sex. The first control group contained healthy individuals (CN) and the second patients with transient ischaemic attacks (AIT). Of the patients with AGT, 70% were women and 30% men. Their average age was 60 (range 14-76). The attacks were abrupt in onset in 100%. In 8% there was a recognisable trigger factor (driving, physical exercise, etc). The average duration was 7 hours. On study of the cardiovascular risk factors, it was found that 36% were hypertensive, 24% had cardiopathy, 12% had diabetes mellitus, 8% were smokers, 4% had polycythaemia, 16% had hyperlipidaemia, 4% were alcoholics. There was a history of migraine in 29%. No patient had a past history of epilepsy. Further investigation showed ECG changes in 12%. In 24% there were non-specific changes in the EEG. On cerebral CT scan there were lesions compatible with ischaemia in 12.5% of the patients. Levels of arterial hypertension were significantly higher in the AGT group as compared to the normal control group (Odds ratio 7.86; CI. 1.29-11.38). A past history of migraine was seen to be a risk factor associated with AGT as compared with both groups of controls (AGT/CN Odds ratio 9.47; CI 1.01-444.92; AGT/AIT Odds ratio > 1.72).