Patients in Minimally Conscious State May Still Feel Pain

TUESDAY, Oct. 7 (HealthDay News) -- Severely brain-damaged patients in a "minimally conscious state" may still feel pain and require painkilling treatment, according to European researchers.

A minimally conscious state (MCS) is different than a persistent vegetative state (PVS), which involves wakefulness without awareness of self or surroundings. MCS patients do show some evidence of awareness of self and their surroundings.

However, caregivers have difficulty assessing MCS patients' levels of conscious pain based on their behavior, according to background information in the study by Dr. Steven Laureys, of the Coma Science Group at the University of Liege, Belgium, and colleagues.

They compared brain activity following electrical stimulation of the median nerve in five MCS patients (ages 18 to 74), 15 PVS patients (ages 18 to 75), and 15 healthy people (ages 19 to 64). The researchers focused on brain areas responsible for pain sensation (the cortical pain matrix), including the thalamus, the primary somatosensory cortex, and the insular, frontoparietal and anterior cingulate cortices.

The MCS patients showed the same level of activity in these areas as healthy people and significantly more activity than PVS patients. The MCS patients also showed better "connectivity" between different brain regions responsible for pain than PVS patients.

"These findings might be objective evidence of a potential pain perception capacity in patients with MCS, which supports the idea that these patients need painkilling treatment," the researchers concluded.

The study was published online by The Lancet Neurology and was expected to be in the November print edition of the journal.

"Increased understanding of the neural processing that can take place in the absence of the conscious awareness, and the patterns of neural activity that are associated with volitional action and conscious experience will undoubtedly shed light on the mechanistic differences among the highly heterogeneous, but functionally restricted, population of patients with disorders of consciousness," Dr. John Whyte, of the Moss Rehabilitation Research Institute in Elkins Park, Pa., wrote in an accompanying comment.