Behavioral signs of recovery from unresponsive wakefulness syndrome to emergence of minimally conscious state after severe brain injury

Precise description of behavioral signs denoting transition from unresponsive wakefulness syndrome/vegetative state (UWS/VS) to minimally conscious state (MCS) or emergence from MCS after severe brain injury is crucial for prognostic purposes. A few studies have attempted this goal but involved either non-standardized instruments, limited temporal accuracy or samples, or focused on (sub)acute patients. The objective of this study was to describe the behavioral signs that led to a change of diagnosis, as well as the factors influencing this transition, in a large sample of patients with chronic disorders of consciousness after severe brain injury. In this retrospective cohort study, 185 patients in UWS/VS or MCS were assessed with the Coma Recovery Scale Revised (CRS-R) five times within the two weeks following their admission to a neurorehabilitation center and then weekly until emergence from MCS, discharge or death. Of these 185 patients, 33 patients in UWS/VS and 45 patients in MCS transitioned to another state. Transition to MCS was mostly denoted by one behavioral sign (72%), predominantly visual fixation (57%), followed by localization to noxious stimulation (27%), visual pursuit (21%) and object manipulation (12%), and could be predicted by etiology, time post-injury and age. Emergence from MCS was characterized by one sign in 64% of patients and by two signs (functional communication and objects use) in the remaining cases, and could be predicted by time post-injury and number of behavioral signs at admission. Clinicians should be therefore advised to pay particular attention to visual and motor subscales of the CRS-R to detect behavioral recovery.