VOL: 100, ISSUE: 27, PAGE NO: 33
What is it?
- Transient global amnesia (TGA) is a temporary and isolated disorder of the memory.
- An episode of this disorder consists of a loss of recent and new memories.
- An episode of TGA usually occurs spontaneously.
- The syndrome is largely benign in nature due to the fact that the episode is temporary.
- The patient is usually otherwise healthy and middle aged or older.
- An attack may last several hours.
- TGA was first described in 1956 by Morris Bender.
- Since then, TGA has become a well-explained syndrome but its cause is still not totally understood.
- TGA affects memory function.
Although many mechanisms have been proposed, no single cause can fully explain all the features of TGA.
- Some authors have stated that patients with TGA have age and risk factor profiles similar to those of patients who experience stroke or transient ischaemic attack (TIA).
Precipitating factors include:
- Sexual intercourse;
- Heavy physical exercise (usually swimming in cold water);
- There is a small correlation between TGA and patients who suffer from migraines, epileptic fits, and cerebrovascular disease;
- Physical or emotional stress;
- Driving a car.
- The precise pathophysiology of TGA is not clear.
- Blood flow to specific brain areas that involve memory including the thalamus and/or mesial temporal structures appears to be disrupted transiently during TGA.
- Three people per 100,000 of the population per year are affected with TGA.
- The condition affects 50 per cent more men than women.
- Less than 25 per cent of patients experience repeated episodes.
- Less than three per cent of patients experience three or more episodes.
- Permanent memory loss is rare.
A patient with TGA:
- Is acutely confused;
- Is neurologically intact except for absent memory (for example, remains alert, remembers identity, remembers past experiences);
- Asks relevant questions repeatedly because she or he does not remember the answer;
- Is unable to recall the episode once she or he has recovered;
- Usually maintains her or his semantic memory (long-term memory responsible for retaining knowledge about the world, including the meaning of words and objects) and meta memory (the awareness of what one should know);
- Anterograde amnesia must be present.
- There is no treatment.
- TGA is short-lived.
- Patients with recurrent episodes usually do not experience any increased morbidity.
- Toxin-induced memory loss tends to include inattention and an inability to sustain coherent thought.
- In complex partial seizures, repetitive questioning is not a feature.
- Psychogenic amnesia tends to occur at a younger age and the patient is more likely to have personality changes and not remember personal details.
Transient Global Amnesia (GP notes): www.gpnotebook.co.uk/cache/1557135375.htm