Transient global amnesia

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):

There is no treatment

• no specific treatment is indicated for a typical episode

Reference:

• Owen D et al. Classical diseases revisited: transient global amnesia. Postgrad Med J. 2007 Apr; 83(978): 236-239.
• Spiegel DR et al. Transient global amnesia: current perspectives.Neuropsychiatr Dis Treat. 2017; 13: 2691-2703.
• Portaro S et al. Risk factors of transient global amnesia - Three case reports. Medicine (Baltimore) 2018 Oct; 97(41): e12723.
• Arena JE et al. Long-Term Outcome in Patients With Transient Global Amnesia: A Population-Based Study.Mayo Clin Proc. 2017 Mar; 92(3): 399-405.
• Hodges J R, Warlow C P. Syndromes of transient amnesia: towards a classification. A study of 153 cases. J Neurol Neurosurg Psychiatry 1990 53834-843