For professionals

Abstract

Objective
To investigate changes in autonomic nervous system (ANS) activity associated with recovery to consciousness in the postacute phase after severe traumatic brain injury (sTBI).

Methods
Skin conductance and heart rate reactivity to sensory stimulation were recorded every 2 weeks for an average period of 3.5 months in 16 adolescent patients, during the assessment of their level of consciousness (LoC) and their cognitive and functional behavior.

Results 
Both heart rate variability (HRV) and skin conductance level (SCL) in response to sensory stimulation changed with recovery to consciousness. Indices of HRV and SCL representing autonomic nervous system (ANS) sympathetic activity increased with recovery, while indices representing parasympathetic activity decreased. In addition, we saw an increase in the sympathovalgal balance of the ANS during recovery.

Conclusions 
Recovery to consciousness, determined by clinical observation in sTBI in the postacute phase, is related to changes in SCL and HRV during sensory stimulation. ANS reactivity to environmental stimulation can therefore provide objective additional information about the clinical condition of sTBI patients and can contribute to decision-making in the treatment policies of unresponsive patients.

Meaning
These findings show that autonomic reactivity can be informative about how a severely damaged nervous system responds to environmental stimulation and how this reactivity turns into a restorative nervous system.

Keywords
Severe traumatic brain injury, Autonomic nervous system, Consciousness, Vegetative state, Minimal conscious state, Sensory stimulation