Background: It is unknown whether assessment of autonomic pathway integrity in newly injured traumatic cervical spinal cord injury (SCI) patients contributes to their neurological prognosis.
Objective: The objective is to investigate the relationship of heart rate variability (HRV) and sympathetic skin response (SSR) at initial evaluation of American Spinal Injury Association Impairment Scale (AIS) A/B tetraplegic patients, with their short-term neurological recovery.
Methods: In this prospective cohort study, short-term HRV indices and SSR to supra-lesional stimuli were computed in 24 acute traumatic cervical AIS A/B SCI patients at admission for rehabilitation. The relationship of these autonomic parameters with motor and sensory score improvement, AIS grade improvement, and time taken for recovery was tested, respectively, with Spearman's correlation coefficient test, Fisher's exact test, and Kaplan-Meier analysis.
Results: SSR was present in 11 (45.8%) patients at initial evaluation. After rehabilitation, 5 (20.8%) patients improved from AIS A/B to AIS C (greater recovery), while the rest remained at AIS A/B (lesser recovery). Both AIS improvement and mean time for 'greater' recovery did not associate with the presence/absence of SSR. Further, HRV indices did not correlate with improvement in motor or sensory scores.
Conclusions: Interim neurological recovery was not related to autonomic parameters of short-term HRV indices and SSR in the AIS A/B tetraplegic patients of our study. Interestingly, about half of the patients with clinically complete SCI had evidence of preserved autonomic function. Our data add to the knowledge base of autonomic findings in cervical SCI patients and will promote research relating neurophysiological parameters and recovery.
Keywords: autonomic function; heart rate variability; neurological recovery; spinal cord injury; sympathetic skin response.