Mechanisms of virtual reality therapies in acute and chronic pain management : A systematic review

Pain is a major healthcare problem globally. Despite the enormous individual and societal burdens of pain, evidence shows that acute and chronic pain remains inadequately treated, which highlights the need for alternative treatment methods. Virtual reality (VR) has presented itself as a promising alternative strategy for the treatment of pain. The aim of this review was to describe the underlying mechanisms of VR therapies in acute and chronic pain management, and to examine to what extent these mechanisms differ in acute versus chronic pain. Three databases were searched using the search term (virtual reality) AND pain AND (treatment OR intervention OR therapy): Scopus, PubMed and PsychINFO. Of the 560 identified studies, 21 studies were included published between January 2015 and April 2020, of which 11 acute pain studies and 10 chronic pain studies. Both adult and paediatric populations were included in this review. It was found that all acute pain studies used the mechanism of distraction in their VR therapies and two studies also used relaxation. In contrast, most chronic pain studies aimed to reverse cortical misrepresentations through neuromodulatory mechanisms, however, chronic pain studies also employed distraction, relaxation, graded exposure, and biofeedback mechanisms. The findings are discussed using the gate control theory of pain and the neuromatrix theory of pain. These findings are in line with the nature of acute versus chronic pain, as acute pain is accompanied by nociceptive stimuli, whereas chronic pain can occur in the absence of actual tissue damage but is produced by neural networks in the brain and is accompanied with maladaptive but reversible changes in the brain.