Transient global amnesia

Last revised by Rohit Sharma on 20 Apr 2024

Transient global amnesia (TGA) is a clinical syndrome with no clear etiology identified. The syndrome is transient and typically resolves within a few hours. 

Transient global amnesia is most common in the 60-70 year age range 8.

  • migraine, approximately 2.5-fold increased incidence, often in a slightly younger demographic 6,9

Anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms 6. Episodic memories are more-so affected than semantic memories 6. Most cases show complete resolution of symptoms within a few hours from onset of symptoms 6.

Several hypotheses (e.g. epileptic phenomena, stroke, focal ischemia) have been proposed with no consensus on the exact mechanism 1,6.

CT brain and conventional sequences of MRI brain may show no abnormalities, especially while the patient is symptomatic.

Prospective and retrospective studies based on a small number of transient global amnesia patients can detect small punctate regions of abnormally restricted diffusion on DWI/ADC sequences in the CA1 area of the hippocampus (lateral edge of the hippocampal gyrus abutting the temporal horn). These lesions can be bilateral and even multifocal 2-4. These changes generally appear after symptom resolution, and the highest rate of detection is approximately 2 days after symptom onset 6.

No treatment is required. The condition rarely recurs in ~5% of patients 5,6.

  • strategic ischemic stroke (e.g. hippocampal infarct, bilateral forniceal infarct (amnestic syndrome of the subcallosal artery)), typically exists with other neurological deficits 6,7

  • transient epileptic amnesia, typically presents upon waking while TGA does not 6

  • psychogenic amnesia, more-so affects semantic memory compared to episodic memory, while TGA is the opposite 6

  • drug-related amnesia, typically has features of encephalopathy 6

  • post-traumatic amnesia, has a history of trauma 6

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.