Transient Global Amnesia. Evidence against vascular ischemic etiology from diffusion weighted imaging.

The etiology of Transient Global Amnesia (TGA) is still obscure. Diffusion-Weighted-Imaging (DWI) provides conflicting evidence concerning a possible vascular ischemic cause in mesiotemporal structures including the hippocampal region. The question remains open whether conflicting observations resulted from different observation times. DWI was performed at a time interval with known sensitivity for detection of ischemia. Ten patients (5 male, 5 female; mean age of 63 +/- 9, range 41-71 years) with typical TGA were investigated at an average delay of 18 hours (range 6 to 44 hours) between onset of symptoms and magnetic resonance imaging (transversal DW-, T1W- and T2W-MRI). Five patients received apparent-diffusion-coefficient (ADC)-mapping. Cerebrovascular studies (ECG, TTE and extra/transcranial dopplersonographic and duplexultrasonic investigation) and EEG were normal in all patients. DW-MRI-sequences and ADC-maps, if performed, were normal in all patients. Conventional T2W-MRI in 3 out of 10 patients showed microangiopathic subcortical changes and lacunar strokes of older origin. We conclude that TGA does not result from a vascular ischemic etiology in the majority of cases.