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Lack of evidence of acute ischemic tissue change in transient global amnesia on single-shot echo-planar
1Department of Neurology, Klinikum Mannheim, University of Heidelberg, Germany. gass@neuro.ma.uni-heidelberg.de
Background And Purpose:
There is uncertainty concerning the etiology of transient global amnesia (TGA). Previous CT and MRI studies have indicated that permanent structural abnormality is rare in TGA. Diffusion-weighted (DW) MRI is very sensitive to early ischemic parenchymal changes and has recently demonstrated embolic infarction in the posterior cerebral artery territory in 2 TGA patients. We report the findings of DW MRI in 8 patients in acute stages of TGA.
Methods:
Conventional and echo-planar DW MRI was performed in 2 patients in the active phase and 6 patients in the recovery phase (1 to 8 hours after cessation of anterograde memory dysfunction) of spontaneously occurring TGA.
Results:
None of the patients showed signs of hyperintensity on DW images or hypointensity on quantitative apparent diffusion coefficient (ADC) maps to suggest regional decreases of water mobility or acute T2 changes on transverse or coronal slices.
Conclusions:
We were unable to detect ADC or acute T2 changes with echo-planar DW MRI in patients with TGA, which suggests that mechanisms other than ischemic infarction may cause TGA. We did not identify spreading depression-associated changes of the ADC. Further refinement of MRI sequences may be necessary to detect subtle or transient signal change in brain parenchyma.
Insights
Diffusion-weighted MRI did not reveal acute ischemic changes in patients with transient global amnesia (TGA). This suggests TGA may stem from causes other than acute infarction, warranting further investigation with advanced MRI techniques.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- The exact cause of transient global amnesia (TGA) remains unclear.
- Previous imaging studies suggest structural abnormalities are uncommon in TGA.
- Diffusion-weighted (DW) MRI is sensitive to early ischemic changes, with some studies showing infarction in TGA patients.
Purpose of the Study:
- To investigate the utility of DW MRI in detecting acute changes in patients with TGA.
- To explore potential causes of TGA beyond ischemic infarction.
Main Methods:
- Eight patients with spontaneously occurring TGA underwent conventional and echo-planar DW MRI.
- Imaging was performed during the active phase and recovery phase (1-8 hours post-symptom resolution).
Main Results:
- No patients exhibited hyperintensity on DW images or hypointensity on apparent diffusion coefficient (ADC) maps.
- No acute T2 changes were detected on transverse or coronal slices.
Conclusions:
- Echo-planar DW MRI did not detect ADC or acute T2 changes in TGA patients.
- Findings suggest that mechanisms other than ischemic infarction may underlie TGA.
- Further advancements in MRI sequences may be needed to identify subtle or transient brain signal changes.