Swallowing in individuals with disorders of consciousness: A cohort study

After a period of coma, a proportion of individuals with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Individuals with disorders of consciousness (DOC) classically receive hydration and nutrition through an enteral-feeding tube. However, the real impact of the level of consciousness on an individual's swallowing ability remains poorly investigated.

We aimed to document the incidence and characteristics of dysphagia in DOC individuals and to evaluate the link between different components of swallowing and the level of consciousness.

We analyzed clinical data on the respiratory status, oral feeding and otolaryngologic examination of swallowing in DOC individuals. We analyzed the association of components of swallowing and participant groups (i.e., unresponsive wakefulness syndrome [UWS] and minimally conscious state [MCS]).

We included 92 individuals with DOC (26 UWS and 66 MCS). Overall, 99% of the participants showed deficits in the oral and/or pharyngeal phase of swallowing. As compared with the MCS group, the UWS group more frequently had a tracheostomy (69% vs 24%), with diminished cough reflex (27% vs 54%) and no effective oral phase (0% vs 21%).

Almost all DOC participants had severe dysphagia. Some components of swallowing (i.e., tracheostomy, cough reflex and efficacy of the oral phase of swallowing) were related to consciousness. In particular, no UWS participant had an efficient oral phase, which suggests that its presence may be a sign of consciousness. In addition, no UWS participant could be fed entirely orally, whereas no MCS participant orally received ordinary food. Our study also confirms that objective swallowing assessment can be successfully completed in DOC individuals and that specific care is needed to treat severe dysphagia in DOC.