Music Stimulation for People with Disorders of Consciousness: A Scoping Review

Abstract

Music stimulation is considered to be a valuable form of intervention for people with severe brain injuries and prolonged disorders of consciousness (i.e., unresponsive wakefulness/vegetative state or minimally conscious state). This review was intended to provide an overall picture of work conducted during the last decade to assess the impact of music on behavioral and non-behavioral responses of people with disorders of consciousness. Following the PRISMA-ScR checklist, a scoping review was carried out to identify and provide a synthesis of eligible studies published in English during the 2010–2021 period. Three databases (i.e., PubMed, PsycINFO, and Web of Science) were employed for the literature search. Thirty-four studies met the inclusion criteria. Those studies were grouped into three categories based on whether they assessed the effects of: (i) recorded music, (ii) interactive music, or (iii) response-contingent music. A narrative synthesis of the studies of each of the three categories was eventually provided. While the studies of all three categories reported fairly positive/encouraging results, several methodological questions make it difficult to draw conclusions about those results and their implications for intervention programs in daily contexts.

Increase in Low-Frequency Oscillations in fNIRS as Cerebral Response to Auditory Stimulation with Familiar Music

“…It was beyond the aim of this study to assess the specificity for preferred music of the observed cortical response. The main information that we would need to assess the level of consciousness of the patients would be cortical responsivity to any external stimuli; response to favorite music is among the most promising targets to evaluate responsiveness in patients with disorders of consciousness [ 44 ]. Further measurements should be performed intermodally with parallel electrophysiology by means of EEG, acoustic evoked potentials, and/or functional brain imaging with fMRI.…”

A Behavioral Approach to Treatment and Assessment of People with Disorders of Consciousness: The Response-contingent Stimulation Strategy

“…Specifically, responsecontingent stimulation may involve the use of music, such as songs and instrumental pieces, voices of loved ones addressing the patients, as well as multimodal stimulation events (e.g., visual and auditory stimuli that may be delivered alternatively or in combination). Another general similarity between the response-contingent stimulation and the other strategies is that the type of stimulation presented to the patients is considered to be relevant/meaningful and pleasant for them [15,25,28,50,55].…”

“…The response-contingent stimulation strategy typically uses brief stimulation events (e.g., 10-or 15-s events) after each response occurrence. The other strategies generally rely on longer periods of stimulation delivery [15,55].…”

“…A third difference is that the implementation of the response-contingent stimulation strategy relies on the availability of a technology system that monitors through small sensors the patients' responses (even minimal responses such as eye blinking and head or finger movements) and automatically delivers the stimulation right after the emission of those responses [55]. The implementation of the other strategies may be based (a) on simple technology devices that, once switched on, present the stimulation as scheduled, independent of the patients' behavior or (b) on therapists, caregivers, or family members that can introduce variations in the types of stimulation scheduled and/or add forms of interaction with the patients [39,56,57].…”

“…In essence, the brief stimulation periods are delivered immediately after the emission of those specific responses. The responses targeted for stimulation delivery are typically selected based on the fact that (a) they are already present in the patients' repertoire but have a low frequency of occurrence (so such frequency could be increased by a successful stimulation process; see below), and (b) they can be recorded in a reliable manner [51][52][53][54][55].…”