VIEWPOINT
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I feel, therefore I am? Understanding Pain in Disorders of Consciousness By Natalie Osborne
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hen a person’s consciousness is severely impaired after brain damage, they are said to have a Disorder of Consciousness (DOC). DOCs challenge our ideas about what constitutes the conscious human experience, and one of its most compelling mysteries: pain. Pain is a multidimensional psychological and physical experience, combining sensory, cognitive, and emotional processes. Whether or not patients with DOCs can experience pain is currently unknown. However, the answer will profoundly impact their treatment and care, as no single accepted strategy for pain detection and remediation currently exists for these patients.1 To understand the experiences of a person with a DOC, we must first appreciate that human consciousness exists on a spectrum. Severe brain damage, such as oxygen deprivation from a stroke or traumatic injury from a motor vehicle accident, can 32 | IMS MAGAZINE SUMMER 2017 CLINICAL TRIALS
often result in a complete loss of arousal and awareness, known as a coma. While some patients wake up and recover from this state, others get “stuck” in intermediate levels of consciousness, where they can remain for months and even years. For example, Unresponsive Wakefulness Syndrome (UWS, also known as Vegetative State) is defined as a return of arousal (e.g., sleep and wake cycles) without awareness. UWS patients can breathe on their own, sit up, and even look around the room. However, they do not appear to have awareness of their environment, and the behaviours they show (moving, swallowing, vocalizing, and even smiling, laughing, and crying) are considered reflexive and unconscious. Patients in a Minimally Conscious State (MCS) show fluctuating, intermittent signs of awareness. MCS patients make purposeful movements, recognize familiar objects, and can even respond to simple commands, such as
“move your right hand” or “touch your nose.” There are many potential sources of pain for DOC patients, including severe brain injury and spasticity, as well as bedsores, muscle atrophy, and limb contraction brought about by prolonged immobility. But without conscious awareness of the world around you, does a painful stimulus register as pain? Without awareness of the self, can the unpleasantness and suffering associated with pain be felt? Because DOC patients cannot communicate, there is no way to know for certain what they are experiencing. Medicine urgently needs a more thorough understanding of the experience of pain in DOC patients to inform clinical management and treatment options. Currently these options are few, as the very existence of pain in DOCs is disputed in the literature. Some physicians