Can functional imaging assess consciousness in noncommunicative patients?

In noncommunicative patients, after excluding a locked-in syndrome (LIS) in which patients are conscious but have extensive motor impairment, the clinician searches for relevant motor activities indicating that the patient is in a minimally conscious state (MCS) rather than in a vegetative state (VS). The state of patients with disorders of consciousness (DOC) is assessed and defined by determining the extent of purposeful motor activity and awareness of environmental stimuli; this can be accomplished by bedside examination. Equally important, however, is the assessment of other properties of human consciousness, including self-awareness, will, decision-making, conflict processing, and social and emotional functions. Improved tools might offer some insight into these latter cardinal components of consciousness.

Rodriguez Moreno et al.,¹ in this issue of Neurology®, describe a study that uses fMRI to explore complex mental activities in patients with DOC. The activation test consisted of asking subjects to “name to themselves” objects pictured in drawings. The authors assessed cerebral activity during this covert naming task in 10 patients with DOC and found in 9 of them hemodynamic responses in some or all areas constituting the network activated in normal subjects. This network comprises regions involved in visual perception, language processing, and action …