Vascular Risk Factors and Internal Jugular Venous Flow in Transient Global Amnesia: A Study of 165 Japanese Patients

Abstract

Background: The etiology of transient global amnesia (TGA) remains unclear. We studied the pathophysiology of TGA in 165 Japanese patients.

Subjects and methods: TGA was diagnosed in hospitalized patients from 2004 to 2015. We analyzed clinical characteristics, magnetic resonance imaging findings, and maximum intima-media thickness of the common carotid artery, and the reflux of internal jugular venous (IJV) flow by ultrasonography, and statistically compared patients with TGA with age-matched and sex-matched patients who have had a transient ischemic attack (TIA), small-vessel occlusion (SVO), and normal controls (each group, N = 165).

Results: Patients with TGA showed lower prevalence of vascular risk factors than patients with TIA and SVO did. Eleven patients (6.7%) had 2 episodes of TAG, but specific clinical variables could not be recognized in these patients. The maximum intima-media thickness was significantly thinner in TGA (1.1 ± .7 mm) than in SVO (1.6 ± .9 mm; P = .001). The percentages of cases whose IJV flow reflux was increased by Valsalva maneuver showed no difference (P = .573) between TGA (26.0 %) and SVO (29.4%). MR diffusion-weighted imaging yielded small hyperintense signals in the hippocampus in 64 of 90 (71.1%) patients between 24 and 72 hours. Potential precipitating specific factors or events before the attacks could be recognized in 40 cases (24.2%) of 165 patients.

Conclusion: Arterial ischemia and IJV flow reflux might not contribute to TGA pathophysiology. The vulnerability of the hippocampus to physical or emotional stress might be suspected as an underlying mechanism in some patients with TGA.

Keywords: MRI; Transient global amnesia; internal jugular venous flow; precipitating specific events; vascular risk factor.