Ictus amnésique

Transient global amnesia (TGA) is a rare neurological disorder. It usually occurs after the age of 50 years. It consists in an anterograde amnesia of brutal onset, lasting less than 24 hours with a lacunar amnesia of the episode. Repetitive questioning and retrograde amnesia are often observed. Clinical examination and interview of the witnesses are crucial in the diagnosis of TGA. They must also be oriented towards differential diagnosis such as stroke or epilepsy. Brain MRI may be normal if realized too soon. It will be most sensitive between 48 to 72 hours after symptoms onset. It will show impaired diffusion limited to the mesiotemporal region. A precipitating event will frequently be found with a predominance of physical events in men (Valasalva-associated manoeuvres, brutal change in temperature or sexual intercourse) and a predominance of psychological events in women. Past medical history of migraine or psychiatric disorders are risk factors of TGA. The origin of TGA remains unclear. Epidemiological, clinical and paraclinical arguments invalidate the hypothesis of an ischemic or an epileptic origin. Veinous, migraine-like and metabolic mechanisms are disputed.