Transient global amnesia with a high signal intensity lesion in medial temporal lobe on diffusion-weighted MRI

Abstract

The etiology of transient global amnesia (TGA) is still obscure. TGA had been recognized as a disease without abnormal findings on neuroimaging especially in the idiopathic form, before new methods of brain MRI was practicable. Recently, diffusion-weighted MRI provided conflicting evidence concerning a possible vascular ischemic cause in mesio-temporal structures including the hippocampal region. Case : A 63-year-old female suddenly became to unable to keep her recent memory without histories of trauma or epilepsy. She showed no abnormal neurologic findings except for the recent memory loss. She has no history of hypertension or diabetes mellitus. Brain MRI performed within 2days after onset demonstrated no abnormality on T1- and T2-weighted images. Diffusion-weighted image showed hyperintensity in the left medial temporal lobe, and the apparent diffusion coefficient in this region was lower than that in the contralateral region. TGA was completely resolved 24 hours after onset