DIFFUSION-WEIGHTED MRI IN TRANSIENT GLOBAL AMNESIA - ELEVATED SIGNAL INTENSITY IN THE LEFT MESIAL TEMPORAL-LOBE IN 7 OF 10 PATIENTS

Prompted by the findings of previous studies with positron emission to mography and single photon emission computed tomography, which demonst rated hypoperfusion or hyperperfusion in the left temporal lobe in iso lated patients with transient global amnesia (TGA), we compared the se nsitivity of diffusion-weighted (DW)? magnetic resonance imaging (MRI) with that of conventional T1- and T2-weighted MRI in patients with TG A. Ten patients with the typical syndrome of a pure TGA were included in the study. For all patients, a coronal DW sequence, a steady-state free precession (SSFP) sequence, and conventional T1- and T2-weighted turbo spin-echo sequences were obtained. Seven of the 10 patients had elevated signal intensity in the left hippocampal region on DW MRI; mo reover, 3 of these 7 patients exhibited bilateral signal abnormality i n this sequence. All conventional T1- and T2-weighted images as well a s all follow-up studies were normal. The signal elevation in DW MRI co rrelates with a decrease in the interstitial space and with cellular e dema in the temporal lobe during TGA. The underlying pathomechanism ca using this cellular edema cannot be clearly outlined using DW MRI. Our data are, however, compatible with spreading depression. This is the first study to show that DW MRT is a sensitive MRI method for evaluati ng TGA, especially in the early stage of the disease.