Relationship between pulsatility index and stroke severity in patients with unilateral pontine infarction due to small vessel occlusion

Background: Pulsatility index (PI) is a useful hemodynamic index that is generally thought to reflect arterial stiffness and distal microvascular resistance. We hypothesized that the PI in the basilar artery is associated with stroke severity in patients with acute unilateral pontine infarction. Methods: We retrospectively enrolled 129 patients with acute unilateral pontine infarction due to small vessel occlusion who presented within 48 hours of symptom onset between January 2015 and December 2020. Transcranial Doppler studies were performed within 5 days of symptom onset in all patients. We analyzed the relationship between the PI measured in the basilar artery and initial stroke severity using correlation and multivariable regression analyses. Results: The median age of the patients was 68.0 years (IQR, 59.5–74.0) and 87 (67.4%) were male. The PI was positively correlated with the National Institutes of Health Stroke Scale (NIHSS) score (r = 0.222, p = 0.011) and ischemic lesion volume (r = 0.187, p = 0.039). Multivariable analysis confirmed that a higher PI was an independent and significant predictor of a higher admission NIHSS score (B, 2.530; 95% confidence interval, 0.195 to 4.866; p = 0.034). In the mediation analysis, ischemic lesion volume had a complete mediating effect on the relationship between the PI and NIHSS score at admission (Z = 2.012, p = 0.043). Conclusions: Increased PI in the basilar artery was associated with severe stroke in patients with acute unilateral pontine infarction.