Long-term outcomes of chronic minimally conscious and vegetative states.

Objective: 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. Methods: 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. Results: 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. Conclusions: 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.