Blood Pressure Variability and Ocular Vestibular-Evoked Myogenic Potentials Are Independently Associated With Orthostatic Hypotension.

Background and purpose: We delineated the association between otolithic dysfunction and blood pressure (BP) variability.

Methods: We prospectively recruited 145 consecutive patients (age=71 [59-79] years, median [interquartile range]; 76 females) with orthostatic intolerance between December 2021 and December 2023 at a tertiary hospital in South Korea. Each patient underwent evaluations of cervical and ocular vestibular-evoked myogenic potentials (oVEMPs), 24-h noninvasive ambulatory BP monitoring (ABPM), and a head-up tilt-table test using the Finometer device. As measures of BP variability, the standard deviations (SDs) of the systolic BP (SBP_SD) and the diastolic BP were calculated based on serial ABPM recordings. Patients were divided into those with orthostatic hypotension (OH, n=68) and those with a normal head-up tilt-table test despite orthostatic intolerance (NOI, n=77) groups.

Results: A multivariable logistic regression analysis showed that OH was associated with bilateral oVEMP abnormalities (p=0.021), SBP_SD (p=0.012), and female sex (p=0.004). SBP_SD was higher in patients with OH than in those with NOI (p<0.001), and was not correlated with n1-p1 amplitude (p=0.491) or normalized p13-n23 amplitude (p=0.193) in patients with OH. The sensitivity and specificity for differentiating OH from NOI were 72.1% and 67.5%, respectively, at a cutoff value of 12.7 mm Hg for SBP_SD, with an area under the receiver operating characteristic curve of 0.73.

Conclusions: Bilaterally deficient oVEMP responses may be associated with OH regardless of 24-h BP variability, reflecting the integrity of the otolith-autonomic reflex during orthostasis. Alternatively, 24-h BP variability is predominantly regulated by the baroreflex, which also participates in securing orthostatic tolerance complementary to the vestibulo-autonomic reflex.