Swallowing in patient with disorders of consciousness: A behavioral study

Introduction: After a period of coma, a proportion of patients with severe brain injury remain in an altered state of consciousness before regaining partial or complete recovery. Patients 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 a patient’s swallowing ability remains poorly investigated.
Objective: The aims of this study were to document the incidence and characteristics of dysphagia in patients DOC and to evaluate the link between different components of swallowing and the level of consciousness.
Method: We retrospectively analyzed clinical data on the respiratory status, oral feeding and otolaryngologic examination of swallowing of DOC patients admitted for a one-week multimodal assessment of consciousness.
Results: A total of 92 DOC patients were included, 26 patients with unresponsive wakefulness syndrome (UWS) and 66 in minimally conscious state (MCS). Deficits in the oral and/or pharyngeal phase of swallowing were present in 99% of the patients. Compared to MCS patients, UWS patients were more frequently tracheotomized (69% UWS vs 24% MCS) with diminished cough reflex (27% UWS vs 54% MCS) and no effective oral phase (0% UWS vs 21% MCS).
Conclusion: almost all patients with DOC presented at least one swallowing disorder, which represents the most important proportion of dysphagia in neurological population. Some components of swallowing (i.e., tracheostomy, cough reflex and efficacy of the oral phase of swallowing) correlate with the level of consciousness. In particular, the efficacy of the oral phase was not observed in any of the UWS patients, suggesting that its presence may be a sign of consciousness, and consequently, it should be taken into account in DOC diagnosis. Our study also confirms that objective swallowing assessment can be completed in DOC patients, and that specific care is needed to treat severe dysphagia in DOC patients.