The role of stimulus-induced skin conductance in disorder of consciousness: A systematic review.

In 30 seconds

This systematic review assessed studies using sensory stimulation and skin conductance (SC) recordings in patients with disorders of consciousness (DoC). Nine studies included 134 patients with coma, vegetative state/unresponsive wakefulness syndrome, or minimally conscious state. All used auditory stimulation, while three also used tactile, olfactory, or multisensory stimuli. Emotionally salient or personally relevant stimuli tended to produce stronger SC responses than neutral stimuli, though patient responses were often delayed, attenuated, or inconsistent relative to healthy controls. The review concludes that SC may complement behavioural assessment but should not be used as a standalone diagnostic marker.

Key findings

• The review included nine studies and 134 patients with coma, vegetative state/unresponsive wakefulness syndrome, or minimally conscious state.
• All nine studies used auditory stimulation; three also included tactile, olfactory, or multisensory stimulation.
• Emotionally salient or personally relevant stimuli tended to elicit stronger SC responses than neutral stimuli, but patient responses were often delayed, attenuated, or inconsistent compared with healthy controls.

Why it matters

Behavioural tools alone can make assessment of DoC challenging. SC offers a motor-independent measure of autonomic arousal that may reveal responses not readily captured by observable behaviour. Differentiation between emotional and neutral stimuli may indicate residual autonomic and salience-related processing, supporting further evaluation of SC as one component of multimodal assessment.

What to keep in mind

The evidence comes from only nine studies with heterogeneous stimulation protocols, limiting comparability. Patient responses were also inconsistent, and the review does not establish SC as a standalone diagnostic marker.