Autonomic function and signal complexity reflect level and severity of traumatic spinal cord injury

Observational single-centre cohort study.

To investigate heart rate variability (HRV), baroreflex sensitivity (BRS), and signal complexity (SC) and their relationships with neurological injury level and severity, as well as their prognostic value for six-month mortality and functional recovery in patients with traumatic spinal cord injury (TSCI).

Uppsala University Hospital, Sweden.

This study included 164 adult patients with TSCI treated in neurointensive care (NIC) (2008-2022). Continuous high-frequency physiological data from the first 7 post-injury days were analysed to derive HRV, BRS, and SC for heart rate (HR), mean arterial pressure, systolic blood pressure, and diastolic blood pressure (DBP). Associations with neurological injury level, injury severity, NIC physiology, neurological improvement, and six-month mortality were assessed.

Patients with cervical injuries had higher HRV, BRS (both p < 0.01), and SC for DBP (p < 0.05) than those with thoracic injuries. Complete cervical injuries had higher HRV (p < 0.05), but lower HR SC (p < 0.01) compared with incomplete cervical injuries. Higher HR SC was associated with neurological improvement at discharge (odds ratio 1.08 [95% confidence interval 1.01-1.16]; p < 0.05), whereas higher HRV was associated with increased six-month mortality (odds ratio 1.01 [95% confidence interval 1.00-1.02]; p < 0.05). Other autonomic and complexity measures showed limited prognostic value.

Systemic autonomic indices after TSCI vary with injury level and severity and may capture distinct aspects of autonomic dysfunction beyond clinical grading. However, their limited prognostic value for neurological recovery and mortality suggest that outcome prediction after TSCI may depend more on other clinical factors and, possibly, more direct intraspinal physiological markers.

NA.