Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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May 21, 2012 (MAIN)
Transient Global Amnesia
- Defined as a sudden onset of antegrade amnesia that lasts up to 24 hours.
- Pathophysiology: not clearly known. Vasospasm (migraine-like), focal ischemia, venous flow abnormality and epileptic phenomena proposed. Related to vulnerability of CA1 neurons subfield of the hippocampal's cornu ammonis to metabolic stress.
- Diagnosis: based on Caplan and Hodges criteria supported by MRI.
- Key Diagnostic Features: Focus(i) of hypersignal intensity on DWI and T2-WI in the medial temporal lobes - hippocampi (mainly, lateral region belonging to CA1 subfield). Normalization around day 10. Imaging may be negative at the acute phase. Regarding the small size of TGA lesions, DWI sequence performed with 3mm thickness and with higher b-values (b=2000 or 3000) may increase detection. DWI changes may be reversible. MRS may demonstrate a lactate peak, a marker of anaerobic glycolisis.
- DDx: Infarction, seizure
- Rx: Self-resolving condition
