Disorders of consciousness: A taxonomy to be changed?

We read with interest the letter by Dolce et al. [1] on the need of a formal nosographic revision of vegetative state. In this respect, Laureys et al. [2] recently stated that the term ‘vegetative state’ should be removed, as it commonly has a pejorative undertone (denoting patients as being vegetable-like), thus resulting in discomfort for physicians and caregivers. In order to avoid this denigrating connotation, they suggest to replace ‘vegetative state’ with ‘unresponsive wakefulness syndrome’ (UWS), the last offering a neutral description of patients who show signs of unresponsiveness with preserved wakefulness and emphasizing the complexity and the dynamic recovery potential of the ‘syndrome’ rather than the definitive label of the ‘state’ definition [2]. We agree with the need of a formal nosographic revision within the spectrum of disorders of consciousness; however, we believe that this need, rather than referring to the kindness of formal terms only, arises from the growing necessity of clarifying the neuropathological overlap among vegetative state and other clinical conditions, such as minimally conscious state (MCS) and locked-in syndrome (LIS). To date, vegetative state and LIS have been considered as formally distinct entities: however, it should be highlighted that these syndromes may be mutually associated from a neuropathological perspective. In fact, some patients with vegetative state pass through LIS during recovery of consciousness: this situation does not always occur in the presence of structural brainstem damage but is often associated with a diffuse axonal injury with a functional disconnection syndrome. Consequently, LIS may sometimes represent a recovery phase of vegetative state and a ‘locked-in state’, might be present, to a certain extent, in all behaviourally unresponsive patients, unless we demonstrate that such is not the case (i.e. by means of advanced neurophysiological and neuroimaging techniques). Vice versa, some patients with LIS (with a total form) are not able to communicate by vertical eye movements which usually enable them to reveal themselves and to interact with the environment. This accounts for a high proportion of misdiagnoses and an elevated rate of diagnostic error within the spectrum of disorders of consciousness with an extreme degree of motor imprisonment [3].

In our opinion, the presence of this overlap suggests forgoing terms referring to the lack of consciousness, until we obtain definitive evidence that such is the case. Talking about an ‘unresponsive wakefulness syndrome’ might stimulate physicians to consider this overlap and to search signs of preserved consciousness in all patients who are unresponsive from a neurobehavioural perspective, just preventing dramatic misdiagnoses. However, we have some reservations about the term ‘unresponsive’, which we consider too definitive. Evaluation of responsiveness is subjective and can vary even in cases where the suggested diagnosis is persistent vegetative state. A person described by a professional as unresponsive might be considered responsive by a significant other, who is commonly more able to obtain emotional responses, visual fixation and visual pursuit. We therefore propose to use the term ‘low responsive wakefulness syndrome’ (LRWS) until repeated neurological examinations enable us to unambiguously differentiate between VS, MCS and forms of extreme motor imprisonment. This terminology might also be more easily accepted by family members.

Lastly, we suggest that a thorough assessment of motor system impairment, together with a prompt treatment of spasticity, should be warranted in all unresponsive patients, to establish to what extent motor imprisonment contributes to behavioural unresponsiveness.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.