Transient Global Amnesia
Basics
Description
Description
- Transient global amnesia (TGA) has the following features:
- Episode of amnesia with abrupt onset
- No focal neurologic signs or symptoms
- Temporary, severe, anterograde amnesia:
- Acute inability to form new memories
- Permanent memory gap after the episode
- Temporary short-range retrograde amnesia:
- More recent memories at more risk
- Previously encoded memories unavailable only temporarily
- Gradually improves until only remaining memory deficit is the gap induced by the anterograde amnesia
- Some retrograde loss may be permanent
- Mean duration of symptoms: 4–6 hr
- Majority resolve within 8 hr
- Incidence between 3 and 8 per 100,000 people:
- 75% occur in patients 50–70 yr old
- 10% occur in patients <50 yr
- Rare in patients <40 yr
Etiology
Etiology
- Multimodal MRI, SPECT, and PET have shown some abnormalities of regional blood flow in selectively vulnerable hippocampal structures
- The exact etiology of TGA is unknown; speculated causes are controversial:
- Vasoconstriction due to hyperventilation:
- Psychogenic hyperventilation in setting of age-related cerebrovascular autoregulatory dysfunction
- Hippocampal venous congestion with Valsalva:
- Increased prevalence of internal jugular vein insufficiency on ultrasound
- Intracranial venous reflux not seen
- Migraine (in younger patients)
- Destabilization of the CA1 sector of the hippocampus via glutamate release
- Increased prevalence of migraine history in TGA patients
- No increased frequency of TGA in patients with migraines
- Vasoconstriction due to hyperventilation:
- No correlation between TGA and thromboembolic cerebrovascular disease has been found
- TGA patients in fact have a lower risk of future cerebrovascular events than TIA patients
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Citation
Schaider, Jeffrey J., et al., editors. "Transient Global Amnesia." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307194/all/Transient_Global_Amnesia.
Transient Global Amnesia. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307194/all/Transient_Global_Amnesia. Accessed November 7, 2024.
Transient Global Amnesia. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307194/all/Transient_Global_Amnesia
Transient Global Amnesia [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 November 07]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307194/all/Transient_Global_Amnesia.
* Article titles in AMA citation format should be in sentence-case
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T1 - Transient Global Amnesia
ID - 307194
ED - Barkin,Adam Z,
ED - Shayne,Philip,
ED - Rosen,Peter,
ED - Schaider,Jeffrey J,
ED - Barkin,Roger M,
ED - Hayden,Stephen R,
ED - Wolfe,Richard E,
BT - 5-Minute Emergency Consult
UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307194/all/Transient_Global_Amnesia
PB - Lippincott Williams & Wilkins
ET - 6
DB - Emergency Central
DP - Unbound Medicine
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