Minimally conscious state
A minimally conscious state or MCS is a disorder of consciousness distinct from persistent vegetative state and locked-in syndrome. Unlike persistent vegetative state, patients with MCS have partial preservation of conscious awareness. MCS is a relatively new category of disorders of consciousness. The natural history and longer term outcome of MCS have not yet been thoroughly studied. The prevalence of MCS was estimated to be 9 times of PVS cases (adult and pediatric), or between 112,000 and 280,000 in the US by year 2000. Pathophysiology Neuroimaging Because minimally conscious state is a relatively new criterion for diagnosis, there are very few functional imaging studies of patients with this condition. Preliminary data has shown that overall cerebral metabolism is less than in those with conscious awareness (20–40% of normal) and is slightly higher but comparable to those in vegetative states. Activation in the medial parietal cortex and adjacent posterior cingulate cortex are brain regions that seem to differ between patients in MCS and those from vegetative states. These areas are most active during periods of conscious waking and are least active when in altered states of consciousness, such as general anesthesia, propofol, hypnotic state, dementia, and Wernicke–Korsakoff syndrome. Auditory stimulation induced