Abstract
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 SD(BP) 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.