The TCD hyperemia index to detect vasospasm and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage

• Published in: Journal of neuroimaging 2023-09, Vol.33 (5), p.725-730
• Main Authors: Kim, Yongwoo, Mehta, Amit, Nair, Reshmi, Felbaum, Daniel R, Mai, Jeffrey C, Armonda, Rocco A, Chang, Jason J
• Format: Article
• Language: English
• Subjects: Aneurysm; Carotid arteries; Carotid artery; Confidence intervals; Flow velocity; Hemorrhage; Hyperemia; Ischemia; Neuroimaging; Statistical analysis; Subarachnoid hemorrhage; Ultrasound; Vasoconstriction; Velocity
• ISSN: 1051-2284; 1552-6569
• DOI: 10.1111/jon.13132

Elevated mean flow velocity (MFV) on transcranial Doppler (TCD) is used to predict vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Hyperemia should be considered when observing elevated MFV. Lindegaard ratio (LR) is commonly used but does not enhance predictive values. We introduce a new marker, the hyperemia index (HI), calculated as bilateral extracranial internal carotid artery MFV divided by initial flow velocity. We evaluated SAH patients hospitalized ≥7 days between December 1, 2016 and June 30, 2022. We excluded patients with nonaneurysmal SAH, inadequate TCD windows, and baseline TCD obtained after 96 hours from onset. Logistic regression was conducted to assess the significant associations of HI, LR, and maximal MFV with vasospasm and delayed cerebral ischemia (DCI). Receiver operating characteristic analyses were employed to find the optimal cutoff value for HI. Lower HI (odds ratio [OR] 0.10, 95% confidence interval [CI] 0.01-0.68), higher MFV (OR 1.03, 95% CI 1.01-1.05), and LR (OR 2.02, 95% CI 1.44-2.85) were associated with vasospasm and DCI. Area under the curve (AUC) for predicting vasospasm was 0.70 (95% CI 0.58-0.82) for HI, 0.87 (95% CI 0.81-0.94) for maximal MFV, and 0.87 (95% CI 0.79-0.94) for LR. The optimal cutoff value for HI was 1.2. Combining HI