Pain Perception in Unresponsive Wakefulness Syndrome May Challenge the Interruption of Artificial Nutrition and Hydration: Neuroethics in Action.

Abstract

The voluntary withdrawal of artificial nutrition and hydration (ANH) in patients with severe disorders of consciousness (DoC, e.g., permanent vegetative states) constitutes a fundamental ethical issue extending beyond the boundaries of end-of-life decisions. The term “Vegetative State” was originally adopted to define “an organic body capable of growth and development but devoid of sensation and thought” (1). In this frame, the traditional approach toward the suspension of ANH rested upon the view that patients in the Vegetative State had no residual capability to perceive pain (2, 3). However, over the past few decades, an increasing number of studies (4–11) have shown that strong claims about awareness in patients without behavioral responses to commands are unwarranted. Furthermore, there is again a high percentage of misdiagnoses in the assessment of these patients (12–14). Recently it was proposed the alternative name “unresponsive wakefulness syndrome” (VS/UWS) (15), to define a condition characterized by the absence of response to commands or oriented voluntary movements in the presence of wakefulness. Neuroimaging studies demonstrated the existence of distinctive cerebral responses to noxious stimuli in conditions like VS/UWS and minimally conscious state (MCS) (16–18). Yet, there is no univocal consensus about pain perception in patients with DoC. In a study by Demertzi and colleagues (19), 2,059 medical and paramedical professionals from 32 European countries were asked the following question: “can a patient in vegetative state feel pain?” Over 40% of those surveyed replied that these patients do not feel pain. The percentage was higher among medical doctors compared to paramedical caregivers (54 and 32%, respectively). This view was substantiated by the idea that, in the absence of consciousness, patients were not capable of experiencing and reporting a painful experience. However, recent advances in the pathophysiology of DoC, debunking the original tenet that patients with DoC do not perceive pain, suggest a reconsideration of the voluntary withdrawal of ANH (20). In this manuscript, we will briefly review the recent literature indicating that some patients with DoC reveal a form of residual awareness (21) and that they are capable of perceiving painful stimuli and exhibiting consistent responses to them. Furthermore, empirical evidence in the literature suggests that, when tested with the appropriate tools, these patients can exhibit consistent reactions to emotionally salient stimuli (5, 10, 22–27). Based on these findings, we propose that the voluntary withdrawal of ANH should be carefully reconsidered on medical and ethical grounding.