Cerebrovascular Reactivity Following Spinal Cord Injury.

Background: Spinal cord injuries (SCI) often result in cardiovascular issues, increasing the risk of stroke and cognitive deficits.

Objectives: This study assessed cerebrovascular reactivity (CVR) using functional magnetic resonance imaging (fMRI) during a hypercapnic challenge in SCI participants compared to noninjured controls.

Methods: Fourteen participants were analyzed (n = 8 with SCI [unless otherwise noted], median age = 44 years; n = 6 controls, median age = 33 years). CVR was calculated through fMRI signal changes.

Results: The results showed a longer CVR component (tau) in the grey matter of SCI participants (n = 7) compared to controls (median difference = 3.0 s; p < .05). Time since injury (TSI) correlated negatively with steady-state CVR in the grey matter and brainstem of SCI participants (R_S = -0.81, p = .014; R_S = -0.84, p = .009, respectively). Lower steady-state CVR in the brainstem of the SCI group (n = 7) correlated with lower diastolic blood pressure (R_S = 0.76, p = .046). Higher frequency of hypotensive episodes (n = 7) was linked to lower CVR outcomes in the grey matter (R_S = -0.86, p = .014) and brainstem (R_S = -0.89, p = .007).

Conclusion: Preliminary findings suggest a difference in the dynamic CVR component, tau, between the SCI and noninjured control groups, potentially explaining the higher cerebrovascular health burden in SCI individuals. Exploratory associations indicate that longer TSI, lower diastolic blood pressure, and more hypotensive episodes may lead to poorer CVR outcomes. However, further research is necessary to establish causality and support these observations.