Functional connectivity in disorders of consciousness: methodological aspects and clinical relevance.

This is a Quick Guide about the role of the functional connectivity in the Disorders of Consciousness (DOC). Recent studies on resting state (RS) in DOC, by using functional magnetic resonance imaging (fMRI), showed that functional connectivity is severely impaired above all in the default mode network (DMN). In the vegetative and minimally conscious state, DMN integrity seems to correlate with the level of remaining consciousness, offering the possibility of using this information for diagnostic and prognostic purposes. Although the two principal approaches used in the RS analysis showed several methodological difficulties, especially in DOC patients, functional brain imaging is currently being validated as a valuable addition to the standardized clinical assessments that are already in use.