The Gray Zone of Consciousness: Cognitive Motor Dissociation

Covert consciousness, including cognitive motor dissociation (CMD), occurs in clinically unresponsive patients with brain injury who can willfully modulate their brain activity to comply with motor imagery commands as revealed by functional magnetic resonance imaging, EEG or other technologies. In 2024, the Curing Coma Campaign conducted a gap analysis of the field of covert consciousness and CMD. This article discusses the achievements that have been made in the field since then.

Three major recent achievements include epidemiological data that CMD occurs in up to 25% of unresponsive brain injury patients, the development of convenient tools for detecting CMD at the bedside, and CMD as a biomarker of cerebral reserves that may possibly be exploited pharmacologically for prognostication and rehabilitation. Although many questions remain, recent findings have paved the way for the implementation of CMD screening in clinical routine, also in resource-poor settings, for better prognostication after brain injury and possibly for therapeutic purposes.