Transient Global Amnesia and High-Grade Styloidogenic Jugular Vein Stenosis.

Importance: Pathogenesis of focal hippocampal ischemia in transient global amnesia (TGA) remains unclear but may be of venous origin. Brain magnetic resonance imaging (MRI)-restricted diffusion has considerable limitations as the only current TGA imaging marker, highlighting a critical need for more reliable disease determinants. Objective: To assess whether the severity of unilateral or bilateral styloidogenic jugular vein compression (SJVC), which can impair intracranial venous drainage, could serve as a novel adjunctive imaging risk factor associated with TGA diagnosis. Design, Setting, and Participants: This retrospective case-control study of patients with TGA and hippocampal-restricted diffusion and without TGA but with hippocampal-restricted diffusion and healthy controls was conducted from May 2016 to June 2024 in a single large academic medical center. Exposure: A brain MRI including diffusion-weighted imaging and extended multiplanar volumetric postcontrast sequences revealing the internal jugular veins (IJVs) in the upper neck. Main Outcomes and Measures: Calculations of cross-sectional areas and the percentage of SJVC stenosis in both IJVs were assessed. The primary outcome was the association of right, left, and combined bilateral SJVC stenosis with TGA status. Secondary measures included IJV baseline size and asymmetry. Results: There were 84 approximately age-matched and sex-matched patients and healthy controls (mean [SD] age, 66 [11.7] years) included in this study; 44 (52.4%) were female, and 40 (47.6%) were male. All participants had brain MRIs: 28 with clinical TGA and hippocampal-restricted diffusion (TGA+/MRI+), 28 without clinical TGA but with incidental hippocampal-restricted diffusion (TGA-/MRI+), and 28 controls without TGA or restricted diffusion (TGA-/MRI-). Right IJVs were larger in all groups, left IJVs were significantly smaller in TGA+/MRI+ than in controls (mean [SD] axial area, 45.0 [30.0] mm2 vs 60.7 [27.5] mm2; P = .04), and the combined IJV caliber was significantly smaller in TGA+/MRI+ than in controls (mean [SD] axial areas, 126.7 [37.1] mm2 vs 150.6 [28.8] mm2; P = .009). Left SJVC stenosis was not associated with patient cohort, but right mean (SD) SJVC stenosis was significantly greater in TGA+/MRI+ than in TGA-/MRI+ (70.4% [30.7%] vs 56.7% [24.1%]; P = .01) and in controls (70.4% [30.7%] vs 51.8% [20.1%]; P = .001). Combined mean (SD) stenosis was also greater in TGA+/MRI+ than in controls (67.5% [24.9%] vs 54.6% [16.1%]; P = .01). Logistic regression demonstrated that right SJVC stenosis (odds ratio, 1.36 [95% CI, 1.06-1.75]; P = .007) and combined stenosis (odds ratio, 1.38 [95% CI, 1.02-1.86]; P = .02) were associated with TGA when compared with controls. Conclusions and Relevance: In this case-control study of patients with TGA vs healthy participants, TGA was associated with high-grade SJVC in the presence of small-caliber IJVs, with an approximately 70% right-sided or bilateral IJV stenosis threshold emerging as a promising imaging covariate for supporting the clinical diagnosis of TGA. These results suggest that MRI assessment of SJVC severity may improve diagnostic accuracy in atypical TGA presentations.