Music Therapy and Disorders of Consciousness: Providing Clinical Data for Differential Diagnosis between Vegetative State and Minimally Conscious State from Music-Centered Music Therapy and Neuroscience Perspectives

Abstract

IntroductionDisorders of consciousness (D°C) resulting from severe brain damage encompass a spectrum of acquired conditions that range from coma, vegetative state (VS), minimally con- scious state (MCS) and locked-in syndrome. Coma is defined as unarousable unresponsiveness with no eye opening (Majerus, Gill-Thwaites, Andrews, & Laureys, 2005). Patients in VS demonstrate preserved behavioral sleep-wake cycles and reflexive but not purposeful behaviors (Laureys & Boly, 2007), and show no discernible indications of conscious- ness despite evidence of wakefulness (Giacino et al., 1997). Intermittent wakefulness is evidenced by eye-opening or sleep-wake cycles on EEG; however, they fail to produce any purposeful or voluntary behavior in response to auditory, vis- ual, tactile or noxious stimulation and do not exhibit any sign of language comprehension or expression (Schnakers et al., 2009; Vanhaudenhuyse et al., 2010). refers to a subset of patients who show limited consciousness (Giacino et al., 1997, 2002) and demonstrate unequivocal, but intermittent behavioral evidence of awareness of self or their environment and is defined by the presence of inconsistent but reproduc- ible goal-directed behaviors (e.g., response to command, verbalizations and visual pursuit; see Schiff et al., 2005; Schnakers et al., 2009). Although unable to communicate, patients in show inconsistent nonreflexive behaviors, which are interpreted as signs of awareness of self or environ- ment (Giacino et al., 2002). Contrary to patients in VS, those in retain some capacity for cognitive processing and are able to activate similar brain networks as controls following painful stimulation, which may indicate that they experi- ence pain. Bruno et al. (2011) defined new subcategories for MCS: MCS + that describes high level behavioral responses (i.e., command following, intelligible verbalization or non- functional communication) and MCS that describes low- level behavioral responses (i.e., visual pursuit, localization of noxious stimulation or contingent communication such as appropriate smiling or crying to emotional stimuli). Locked-in syndrome describes patients who are awake and conscious but have no means of producing speech, limb or facial move- ments (American Congress of Rehabilitation Medicine, 1995).Damasio (1999) described consciousness as the operation of specific brain regions and systems, dependent on the activ- ity of a number of phylogenetically old brain structures and emerging as a result of cross-sectional integration of neural activity. Behavioral assessment remains the gold standard for detecting signs of consciousness and, hence, for determining diagnosis (Giacino, Kalmar, & Whyte, 2004; Schnakers et al., 2009). However, behavioral assessment can be complex due to the presence of motor impairment, tracheotomy, fluctuating arousal level or ambiguous responses.Determining objectively whether a patient suffering from a D°C is aware is at the heart of the problem. During the assessment, the interdisciplinary team faces the challenge of distinguishing the patient's level of awareness, in order to determine a differential diagnosis between and the VS. Existing clinical assessment procedures for patients with impaired consciousness sometimes fail to detect the patients' full responsive capacity. Studies have shown that 37 - 43% of patients misdiagnosed with VS demonstrate signs of aware- ness (Schnakers et al., 2009). This high misdiagnosis rate can be associated to fluctuations in the patient's arousal, or his impairments in visual, auditory, motor, or language function that limit his ability to interact with the examiner (Edlow, Giacino, & Wu, 2013). Misdiagnosis can have grave conse- quences, especially in prognosis and end-of-life decision- making (Schnakers et al., 2009), in addition to treatment plan, and medico-legal judgments (Andrews, Murphy, Munday, & Littlewood, 1996; Giacino et al. …