Transient global amnesia
Updates to Article Attributes
Transient global amnesia (TGA) is a clinical syndrome with no clear aetiology identified. Most symptoms areThe syndrome is transient and resolvetypically resolves within a few hours.
Epidemiology
Most common in patients of older age (50-70 years old).
Associations
Clinical presentation
Anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms6. Episodic memories are more-so affected than semantic memories 6. Most cases show complete resolution of symptoms within a few hours from onset of symptoms6.
Pathology
Several hypotheses (e.g. epileptic phenomena, stroke, focal ischemiaischaemia) have been proposed with no consensus on the exact mechanism 1,6.
Radiographic features
Brain CT scanbrain and conventional sequences of MRI brain may show no abnormalities, especially while the patient is symptomatic.
MRI
Prospective and retrospective studies based on a small number of TGA 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.
Treatment and prognosis
No treatment is required and. The condition rarely recurs in ~5% of patients 5,6.
Differential diagnosis
- strategic ischaemic stroke (e.g. hippocampal ischaemic), typically exists with other neurological deficits 6
- 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
condition tends to not recuropposite56. - drug-related amnesia, typically has features of encephalopathy 6
- post-traumatic amnesia, has a history of trauma 6
-<p><strong>Transient global amnesia (TGA) </strong>is a clinical syndrome with no clear aetiology identified. Most symptoms are transient and resolve within a few hours. </p><h4>Epidemiology</h4><p>Most common in patients of older age (50-70 years old).</p><h4>Clinical presentation</h4><p>Anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms. Most cases show complete resolution of symptoms within a few hours from onset of symptoms.</p><h4>Pathology</h4><p>Several hypotheses (e.g. epileptic phenomena, stroke, focal ischemia) have been proposed with no consensus on the exact mechanism <sup>1</sup>.</p><h4>Radiographic features</h4><p>Brain CT scan and conventional sequences of MRI brain show no abnormalities.</p><h5>MRI</h5><p>Prospective and retrospective studies based on a small number of TGA patients can detect small punctate regions of abnormally restricted diffusion on DWI/ADC sequences in the CA1 area of the <a href="/articles/hippocampus">hippocampus</a> (lateral edge of the hippocampal gyrus abutting the temporal horn). These lesions can be bilateral and even multifocal <sup>2-4</sup>. </p><h4>Treatment and prognosis</h4><p>No treatment is required and the condition tends to not recur <sup>5</sup>.</p>- +<p><strong>Transient global amnesia (TGA) </strong>is a clinical syndrome with no clear aetiology identified. The syndrome is transient and typically resolves within a few hours. </p><h4>Epidemiology</h4><p>Most common in patients of older age (50-70 years old).</p><h5>Associations</h5><ul><li>
- +<a title="Migraine" href="/articles/migraine">migraine</a> <sup>6</sup>
- +</li></ul><h4>Clinical presentation</h4><p>Anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms <sup>6</sup>. Episodic memories are more-so affected than semantic memories <sup>6</sup>. Most cases show complete resolution of symptoms within a few hours from onset of symptoms <sup>6</sup>.</p><h4>Pathology</h4><p>Several hypotheses (e.g. epileptic phenomena, stroke, focal ischaemia) have been proposed with no consensus on the exact mechanism <sup>1,6</sup>.</p><h4>Radiographic features</h4><p>CT brain and conventional sequences of MRI brain may show no abnormalities, especially while the patient is symptomatic.</p><h5>MRI</h5><p>Prospective and retrospective studies based on a small number of TGA patients can detect small punctate regions of abnormally restricted diffusion on DWI/ADC sequences in the CA1 area of the <a href="/articles/hippocampus">hippocampus</a> (lateral edge of the hippocampal gyrus abutting the temporal horn). These lesions can be bilateral and even multifocal <sup>2-4</sup>. These changes generally appear after symptom resolution, and the highest rate of detection is approximately 2 days after symptom onset <sup>6</sup>.</p><h4>Treatment and prognosis</h4><p>No treatment is required. The condition rarely recurs in ~5% of patients <sup>5,6</sup>.</p><h4>Differential diagnosis</h4><ul>
- +<li>strategic <a title="Ischaemic stroke" href="/articles/ischaemic-stroke">ischaemic stroke</a> (e.g. hippocampal ischaemic), typically exists with other neurological deficits <sup>6</sup>
- +</li>
- +<li>transient epileptic amnesia, typically presents upon waking while TGA does not <sup>6</sup>
- +</li>
- +<li>psychogenic amnesia, more-so affects semantic memory compared to episodic memory, while TGA is the opposite <sup>6</sup>
- +</li>
- +<li>drug-related amnesia, typically has features of encephalopathy <sup>6</sup>
- +</li>
- +<li>post-traumatic amnesia, has a history of trauma <sup>6</sup>
- +</li>
- +</ul>
References changed:
- 6. Miller T & Butler C. Acute-Onset Amnesia: Transient Global Amnesia and Other Causes. Pract Neurol. 2022;22(3):201-8. <a href="https://doi.org/10.1136/practneurol-2020-002826">doi:10.1136/practneurol-2020-002826</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/35504698">Pubmed</a>
Image 6 MRI (DWI) ( create )
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