Cardiovascular autonomic function in middle-aged people with long-term cervical and upper thoracic spinal cord injuries.

OBJECTIVES

To examine cardiovascular autonomic function in middle-aged people with long-term cervical and upper thoracic spinal cord injury (SCI) compared with the general population, and explore if the neurological level of injury (NLI) is related to cardiovascular autonomic function.

DESIGN

Population-based cross-sectional study with matched controls.

SETTING

Outpatient SCI unit in Southern Sweden.

PARTICIPANTS

Twenty-five individuals (20% women, mean age 58 years and mean time since injury 28 years, NLI C2-T6, American Spinal Injury Association Impairment Scale A-C) from the Swedish SPinal Cord Injury Study on Cardiopulmonary and Autonomic Impairment (SPICA). Matched controls were obtained from the population-based Swedish CArdioPulmonary bioImage Study (SCAPIS) at a ratio of 5:1.

INTERVENTIONS: Not applicable.

OUTCOME MEASURES: 24 h electrocardiography and deep breathing tests. 24 h ambulatory blood pressure (BP) monitoring and orthostatic BP tests.

RESULTS

In individuals with SCI compared with controls, heart rate variability (24h mean SD of the normal-to-normal interval 112 ms vs 145 ms, P < 0.001) and diastolic orthostatic BP increase (2.0 and 9.4 mmHg, P < 0.001), were significantly lower, whereas BP variability was significantly higher (24h mean systolic SDBP 17.8 mmHg vs 15.7 mmHg, P = 0.029). Circadian patterns of heart rate variability and BP (lack of nocturnal dip) were significantly different among the individuals with SCI than controls. Higher NLI was significantly (P < 0.05) correlated with impairments to various cardiovascular autonomic function variables.

CONCLUSIONS

This exploratory study indicates that cardiovascular autonomic function is impaired in middle-aged people with long-term cervical and upper thoracic SCI compared with the general non-SCI population, and more pronounced with a higher NLI. Future research is needed to understand the pathophysiological mechanisms underlying these impairments, and the prognostic significance for individuals with SCI.

TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03515122.