Transient global amnesia: Signal alteration in 2D/3D T2-FLAIR sequences

Abstract

Purpose: Transient global amnesia (TGA) is one of the most enigmatic syndromes in clinical neurology. The detection rate of TGA lesions in 2D/3D FLAIR sequences has not been evaluated. Methods: A total of 201 patients (44 men and 157 women; mean age, 60.34 +/- 9.23 years; range, 22-91 years) diagnosed with TGA, who underwent diffusion-weighted imaging (DWI; b = 1000 s/mm(2), b = 2000 s/mm(2), 4 mm) and/or 2D/3D-FLAIR sequences (4 mm, 0.9 mm; respectively) using 3-T MRI within 28 days after onset of TGA symptoms, were included in this single-center, retrospective, cross-sectional study. Hippocampal lesions were visually assessed in all sequences and detection rates were analyzed according to imaging timing (1 day, 2-4 days, 5-7 days, 8-11 days, and 12-28 days) and kinds of sequences. Results: The detection rates were highest 2-4 days after symptom onset in all sequences, and that was higher in order of b = 2000 (75.28% [67/89]), b = 1000 (63.92% [62/97]), 3D-FLAIR (59.38% [19/32]), and 2D-FLAIR (15.15% [15/99]). On FLAIR sequences, detectability was lower 5-7 days after onset than that 2-4 days after onset (2D-FLAIR, 15.15% [15/99] vs. 5.56% [1/18]; 3D-FLAIR, 59.38% [19/32] vs. 0.00% [0/1]). Conclusion: FLAIR signal changes occur in approximately 60% of TGA patients 2-4 days after symptom onset, and decrease after 5 days. It is postulated that the pathophysiology of TGA might differ from common ischemic changes.