Transient global amnesia

Abstract

Transient global amnesia (TGA) is a benign, stress-induced neurological syndrome associated with reversible hippocampal dysfunction that manifests as isolated, predominantly anterograde amnesia. Since it is impossible to make a definitive diagnosis of TGA when the patient is admitted to hospital, the primary condition should be interpreted as an acute cerebrovascular accident, which implies a mandatory neuroimaging examination and clarification of the question of thrombolysis according to general principles. When taking a medical history, attention should be paid to the presence of predisposing conditions and triggers: migraine, chronic and acute stress, physical activity, sudden changes in temperature, Valsalva maneuver, coitus, medical procedures. If amnesia does not resolve within 24 hours, a differential diagnosis with stroke, Wernicke–Korsakoff encephalopathy, limbic encephalitis, intoxication and psychogenic (dissociative) amnesia is required. If the symptoms resolve within 24 hours and the classic diagnostic criteria are met, magnetic resonance imaging of the brain in diffusion-weighted mode is performed on days 2 to 4 in order to detect pinpoint zones of diffusion restriction in the hippocampus. If these lesions are visible and a typical medical history is available, the diagnosis of TGA can be made; if no lesions are present, the diagnosis is probable. In the absence of lesions and an atypical history of TGA, differentiation from transient epileptic or dissociative amnesia and transient ischemic attack is required.