Impact of Subarachnoid Hemorrhage on the Cardiac Autonomic Function During Rehabilitation in Children After Severe Traumatic Brain Injury.

This study aimed to investigate the impact of traumatic subarachnoid hemorrhage (tSAH) on cardiac autonomic control system (CACS) function in children after severe traumatic brain injury (TBI) during the subacute rehabilitation period. Thirty-three participants, 8-18 years of age, 42 (14-149) days after severe TBI at the beginning of the subacute rehabilitation, were included in the study. Six participants were diagnosed with tSAH during acute medical care (tSAH group). Heart rate variability (HRV) was assessed by the standard deviation of the N-N interval (SDNN) and the square root of the mean square differences of successive R-R interval (RMSSD) using a Polar RS800CX device while sitting at rest for 5 min. A second assessment was performed 8 weeks later. No significant difference between the tSAH and non-tSAH groups were found in the demographic and functional characteristics or injury severity. However, in comparison to the non-tSAH group, the tSAH group had lower SDNN (23.9 [10.5-47.3] vs. 43.9 [21.8-118.8], respectively;  = 0.005) and RMSSD values (11.8 [5.9-24.5] vs. 29.6 [8.9-71.7], respectively;  = 0.004). Neither group demonstrated changes in HRV values at rest in the second assessment, whereas the significant difference in SDNN ( = 0.035) and RMSSD ( = 0.008) remained. Children diagnosed with SAH after severe TBI presented poorer CACS function during the subacute rehabilitation. Given that reduced HRV values may be a marker for potential heart disease, the medical team should be aware of the influence of existing tSAH. Future studies with larger sample sizes and longer follow-up periods are warranted to further investigate this topic. ClinicalTrials.gov number: NCT03215082.