Long-term outcomes of chronic minimally conscious and vegetative states

The present retrospective cohort study compares the long-term functional outcome, improvement or deterioration, of patients considered in a vegetative state (VS) or a minimally conscious state (MCS) 1 year after coma onset, then yearly for up to 5 years.

We reviewed the clinical courses of 12 patients in VS and 39 in MCS. The outcomes were assessed at 2, 3, 4, and 5 years after injury using the 5 categories of the Glasgow Outcome Scale plus an additional category for patients in MCS. A logistic regression analysis investigated the relationships between each outcome and 10 predictor variables. Four of these variables were auditory evoked potentials recorded at the early stage of coma.

None of the patients in VS improved during the follow-up period: 1 was lost to follow-up, 9 died, and 2 remained in VS. Among patients in MCS, 3 were lost to follow-up, 14 died, 9 remained in MCS, and 13 emerged from MCS with severe disabilities. VS, age >39 years, and bilateral absence of cortical components of middle-latency auditory evoked potentials were significantly associated with deterioration.

In contrast to patients in VS, a third of patients in MCS improved more than 1 year after coma onset. This emphasizes the need to define reliable boundaries between VS and MCS using repeated clinical evaluations and all imaging and neurophysiologic tools available today.