Embodied Virtual Reality for Chronic Pain

With roughly 1 in 5 affected individuals, chronic pain is incredibly widespread on a global scale. Unfortunately, standard opioidergic treatment does not consistently provide adequate relief and is often tied to adverse events. As a novel and innovative approach in pain management, virtual reality (VR) creates interactive, multimodal sensory stimuli that have demonstrated considerable success in reducing pain. Much research has focused on VR's ability to shift patients' attention away from pain; however, these methods provide only transient relief through means of distraction and therefore do not offer long- term analgesic remediation. A different and promising therapeutic approach is to utilize VR as an embodied simulation technique, where virtual body illusions can be used to improve body perception and produce potentially more enduring analgesia.

Disturbances in body perception (i.e., alterations in the way the body is perceived) are increasingly acknowledged as a pertinent feature of chronic pain. Compared to healthy individuals, patients afflicted with chronic pain exhibit alterations in neural areas involved in body perception. Subjectively, patients with chronic pain report aberrations in body perception that include alterations in perceived shape, size, or color that differ from objective assessment (e.g., experiencing painful body parts as enlarged, twisted, or otherwise distorted. Furthermore, the degree of body perception distortion positively correlates with pain, where those in more severe pain also report more extensive body perception disturbances. Interestingly, interventions aimed at reducing body perception distortion correspondingly ameliorate pain, and several studies have evinced that modulating body perception with the use of (non-virtual) body illusions (i.e., multisensory modulations of perceived embodiment) can elicit significant and even sustained analgesia in patients with chronic pain. Distorted perceptions of the body therefore constitute a promising target for pain modulation. Recent experimental and clinical research has demonstrated the analgesic efficacy of body illusions in a range of chronic pain conditions, including (but not limited to) osteoarthritis (OA), complex regional pain syndrome (CRPS), and neuropathic pain. For example, illusory stretching of the hands in patients with OA reduced pain by 40%. Furthermore, pain relief following a single illusion has been shown to persist between several minutes up 10 weeks, suggesting that multiple sessions of body illusions could reduce cortical misrepresentation over time and lead to long-term analgesia.

Immersive VR multisensory feedback training signifies a promising new avenue for potential future approaches aimed at the management of chronic pain by supporting the design of targeted virtual environments to alter (distorted) body perceptions. The multimodal stimulus control of VR enables physical-to-virtual body transfer illusions, resulting in the feeling that the virtual body is one's own. These virtual body illusions can modulate body perception with ease and could therefore be used to alter the perceived properties of pain: disturbed body perception in patients with chronic pain can thereby be improved by adapting the virtual body in ways that would not be possible with the physical body. The current study can be classified as risk category A, since it entails only minimal risks and burdens (i.e., potential but unlikely transient dizziness and nausea in VR).

The investigators hypothesize that virtual reality will reduce pain intensity ratings from pre- to post-virtual reality session. However, it is expected that virtual body illusions will lead to stronger analgesia, since the virtual body illusions additionally aim to target and normalize body perception disturbances that are associated with chronic pain. While analgesia is expected immediately following the VR distraction in the control group, cumulative improvements or sustained analgesia, nor any improvements in body perception disturbances are not expected. Additionally, the investigators therefore also hypothesize that virtual body illusions, but not virtual distraction, will reduce body perception disturbances.

This single center project will consist of confirmatory quantitative research conducted on a national level. The use of virtual reality (i.e., virtual reality as a distraction versus embodiment modality) will be examined as a modulatory interventional tool for pain management in different pain conditions, including complex regional pain syndrome, peripheral nerve injury, and osteoarthritis. To this end, the control condition will consist of the thus far regularly employed virtual distraction (i.e., a relaxing virtual scene of a wooded area to distract participants from pain), in which they will be immersed over several sessions, versus an experimental condition, wherein participants will be able to both choose from several virtual body illusions to identify which one best reduces their pain and body perception disturbances, and be immersed in the preferred/chosen virtual body illusion of choice over several sessions.