An interesting section from neuropsychiatrist Michael Kopelman’s 2002 review article on the neuropsychology of memory disorders where he tackles transient global amnesia – a form of brief, severe, but mysterious amnesia that resolves in a few hours. No-one really knows what causes the majority of cases.
Transient global amnesia (TGA) most commonly occurs in the middle-aged or elderly, more frequently in men, and results in a period of amnesia lasting several hours. As is well known, it is characterized by repetitive questioning, and there may be some confusion, but patients do not report any loss of personal identity.
It is sometimes preceded by headache or nausea, a stressful life event, a medical procedure, intense emotion or vigorous exercise. Hodges and Ward (1989) found that the mean duration of amnesia was 4h and the maximum 12h. In 25% of their sample, there was a past history of migraine, which was considered to have a possible aetiological role.
In a further 7%, the patients subsequently developed unequivocal features of epilepsy in the absence of any previous history of seizures. There was no association with either a past history of or risk factors for vascular disease, nor with clinical signs indicating a vascular pathology. In particular, there was no association with transient ischaemic attacks.
In 60-70% of the sample, the underlying aetiology was unclear.
Link to full-text of paper ‘Disorders of memory’.