Hemodynamic responses to static and dynamic motion stimuli in persons with Postural Orthostatic Tachycardia Syndrome with mild traumatic brain injury.

To investigate cardiovascular and hemodynamic responses in both static and dynamic motion stimuli in persons with Postural Orthostatic Tachycardia Syndrome (POTS) and chronic mild traumatic brain injury (mTBI), participants with POTS and mTBI (n = 10) were compared to healthy controls (n = 10). Both cohorts underwent static head-up-tilt tests and dynamic tilt-translation sled tests, with oscillatory interaural axis translation coupled with simultaneous roll tilt in various combinations to alter otolithic stimulation and investigate vestibular-mediated influences. Continuous cardiovascular metrics included heart rate (HR), blood pressure (BP), stroke volume (SV), and cardiac output (CO). During static head-up-tilts, the POTS-mTBI group had greater HR increases (padj = 0.025), whereas there were no group differences for BP, SV, and CO. Responses to dynamic motion stimuli varied depending on the motion profile. For the profile consisting of oscillations in roll tilt, the POTS-mTBI group had greater responses in BP (padj = 0.025). For the cancel motion profile, designed to alter hydrostatic pressure gradients along the body axis while producing no shear force stimulation to the otoliths, the POTS-mTBI group had greater responses in BP (padj = 0.044). In a 20° static tilt, there were no differences between cohorts, while a ± 20° dynamic tilt had larger responses in HR (p = 0.020), BP (p = 0.022), and CO (p = 0.045) in the POTS-mTBI group. Potential vestibular-mediated mechanisms in cardiovascular regulation may be impacted in patients with POTS and mTBI, investigated here by quantifying dynamic motion responses.