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transient global amnesia

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Transient global amnesia (TGA) is a temporary and isolated disorder of memory. The patient is usually over 50 years old and an attack may last several hours.

Patients with this condition are often described - wrongly - as being confused.

The patient with TGA:

is neurologically intact except for absent memory

  • asks pertinent questions repeatedly
  • is unable to recall the episode once they have recovered
  • presents classically with an abrupt onset of severe anterograde amnesia
  • does not have any focal neurological symptoms
  • patient remain alert, attentive, and cognition is not impaired
  • are disoriented to time and place
  • attacks usually last for 1-8 h but should be less than 24 h (1)

Epidemiological data put the annual incidence of TGA between 3.4 and 10.4/100,000 (2)

  • most commonly presents in the seventh decade of life. Across studies, the mean age of an episode ranges from 61 to 67.3 years
  • studies show a slight female predominance
  • study evidence showed a recurrence rate of 6.3% in a 10 year period

Precipitating factors include sexual intercourse and heavy physical exercise, particularly swimming in cold water.

  • possible that it may result from different mechanisms such as venous congestion with valsalva-like activities before symptom onset, arterial thromboembolic ischaemia and vasoconstriction due to hyperventilation (1)

  • close precipitating events for TGA are considered emotional stress (i.e., triggered by gastric endoscopy, birth/death announcement, and difficult/exhausting workday), physical effort (i.e., gardening, house work, and sawing wood), physical exertion (including sexual activity), and water contact/temperature change (i.e., hot bath/shower and cold swim) (3)

  • remote precipitating events, with onset reported weeks prior to TGA, are considered anxiety triggered by conflict at home or work, health problems, and financial stressors (3)

  • diagnosis may be made safely in the presence of a characteristic collateral history

There is a correlation between TGA and migraine. There is no excess of cerebrovascular disease in patients with TGA

  • a population-based study concluded that an episode of TGA does not increase the risk of subsequent cerebrovascular events, seizures, or cognitive impairment (4)

Diagnostic Criteria (5):

Attack must be witnessed

Acute onset of anterograde amnesia must be present

No alteration in consciousness must be present

No cognitive impairment other than amnesia must be present

No loss of personal identity must be present

No focal neurology or epileptic features must be present

No recent history of head trauma or seizures must be present

Attack must resolve within 24h

Other causes of amnesia must be excluded

There is no treatment

  • no specific treatment is indicated for a typical episode

Reference:

Last edited 08/2020 and last reviewed 08/2020

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