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A significant body of experimental evidence has demonstrated that it is possible to induce the illusion of ownership of a fake limb or even an entire fake body using multisensory correlations. Recently, immersive virtual reality has allowed users to experience the same sensations of ownership over a virtual body inside an immersive virtual environment, which in turn allows virtual reality users to have the feeling of being “embodied” in a virtual body. Using such virtual embodiment to manipulate body perception is starting to be extensively investigated and may have clinical implications for conditions that involve altered body image such as chronic pain. Here, we review experimental and clinical studies that have explored the manipulation of an embodied virtual body in immersive virtual reality for both experimental and clinical pain relief. We discuss the current state of the art, as well as the challenges faced by, and ideas for, future research. Finally, we explore the potentialities of using an embodied virtual body in immersive virtual reality in the field of neurorehabilitation, specifically in the field of pain.

A significant body of experimental evidence has demonstrated that it is possible to induce the illusion of ownership of a fake limb or even an entire fake body using multisensory correlations. Recently, immersive virtual reality has allowed users to experience the same sensations of ownership over a virtual body inside an immersive virtual environment, which in turn allows virtual reality users to have the feeling of being “embodied” in a virtual body. Using such virtual embodiment to manipulate body perception is starting to be extensively investigated and may have clinical implications for conditions that involve altered body image such as chronic pain. Here, we review experimental and clinical studies that have explored the manipulation of an embodied virtual body in immersive virtual reality for both experimental and clinical pain relief. We discuss the current state of the art, as well as the challenges faced by, and ideas for, future research. Finally, we explore the potentialities of using an embodied virtual body in immersive virtual reality in the field of neurorehabilitation, specifically in the field of pain.

Modifying the visual aspect of a virtual arm that is felt as one's own using immersive virtual reality (VR) modifies pain threshold in healthy subjects, but does it modify pain ratings in chronic pain patients? Our aim was to investigate whether varying properties of a virtual arm co-located with the real arm modulated pain ratings in patients with chronic arm/hand pain because of complex regional pain syndrome (CRPS) type I (without nerve injury) or peripheral nerve injury (PNI). CRPS (n = 9) and PNI (n = 10) patients were immersed in VR and the virtual arm was shown at 4 transparency levels (transparency test) and 3 sizes (size test). We evaluated pain ratings throughout the conditions and assessed the virtual experience, finding that patients with chronic pain can achieve levels of ownership and agency over a virtual arm similar to healthy participants. All 7 conditions globally decreased pain ratings by half. Increasing transparency decreased pain in CRPS but did the opposite in PNI, whereas increasing size slightly increased pain ratings only in CRPS. We conclude that embodiment in VR can decrease pain ratings in chronic arm pain, although the type of pain determines which strategy to decrease pain is most useful. We discuss this through the interactions between body image and pain perception. Perspective: “Embodiment” in VR is useful to decrease pain ratings in chronic pain patients, but the best strategy needs to be tuned to the pain etiology. This approach could potentially help patients with chronic pain and clinicians who seek alternatives to pain management for patients.

BACKGROUND: After discharge, most patients who have suffered a stroke remain with some limitations in their stair climbing ability. This is a critical factor in order to be independent in real-life mobility. Although there are several studies on prognostic factors for gait recovery, few of them have focused on the recovery of stair climbing. AIM: The aim of this study was to identify prognostic risk factors for the recovery of stair climbing ability in a large sample of subjects with subacute stroke. DESIGN: Observational study. SETTING: Neurorehabilitation Inpatient Unit. POPULATION: Subjects within the first month after stroke that had been admitted to an inpatient rehabilitation unit and discharged after an intensive inpatient rehabilitation. METHODS: Demographical and clinical data were collected. Barthel Index (BI), Trunk Control Test and Motricity Index (MI) scores were recorded at admission and at discharge. Patients received two daily 40-minute sessions of motor rehabilitation, six days per week, during approximately two months. Forward Binary Logistic regressions were used to identify the role of risk factors, using as dependent variables the recovery of stair climbing ability and walking ability at discharge. As independent variables we used age, gender, onset-to-admission interval, side of hemiparesis, trunk control, Motricity Index (MI), presence of obesity, presence of neglect, presence of depression, classification of cerebral infarction (total anterior circulation, partial anterior circulation, posterior circulation or lacunar infarcts), degree of independence in activities of daily living, and cognitive state, all assessed at admission. RESULTS: A total of 257 subjects were enrolled. BI-Score, MI-Score and presence of unilateral spatial neglect at admission were able to explain 83% of variance for the recovery of stair climbing ability. Subjects with a BI >40 at admission were about 17 times more likely to be able to climb stairs again than other

Seeing one's own body has been reported to have analgesic properties. Analgesia has also been described when seeing an embodied virtual body colocated with the real one. However, there is controversy regarding whether this effect holds true when seeing an illusory-owned body part, such as during the rubber-hand illusion. A critical difference between these paradigms is the distance between the real and surrogate body part. Colocation of the real and surrogate arm is possible in an immersive virtual environment, but not during illusory ownership of a rubber arm. The present study aimed at testing whether the distance between a real and a virtual arm can explain such differences in terms of pain modulation. Using a paradigm of embodiment of a virtual body allowed us to evaluate heat pain thresholds at colocation and at a 30-cm distance between the real and the virtual arm. We observed a significantly higher heat pain threshold at colocation than at a 30-cm distance. The analgesic effects of seeing a virtual colocated arm were eliminated by increasing the distance between the real and the virtual arm, which explains why seeing an illusorily owned rubber arm does not consistently result in analgesia. These findings are relevant for the use of virtual reality in pain management. Perspective Looking at a virtual body has analgesic properties similar to looking at one's real body. We identify the importance of colocation between a real and a surrogate body for this to occur and thereby resolve a scientific controversy. This information is useful for exploiting immersive virtual reality in pain management.

Music is a potent mood regulator that can induce relaxation and reduce anxiety in different situations. While several studies demonstrate that certain types of music have a subjective anxiolytic effect, the reported results from physiological responses are less conclusive. Virtual reality allows us to study diverse scenarios of real life under strict experimental control while preserving high ecological validity. We aimed to study the modulating effect of music on the anxiety responses triggered by an immersive virtual reality scenario designed to induce fear of heights. Subjects experienced a virtual scenario depicting an exterior elevator platform ascending and descending the total height of its 350 meters tall supporting structure. Participants were allocated to either a group that experienced the elevator ride with background music or without, in a between-groups design. Furthermore, each group included participants with different degrees of fear of heights, ranging from low to high fear. Recordings of heart rate, galvanic skin response, body balance, and head movements were obtained during the experiments. Subjective anxiety was measured by means of three questionnaires. The scenario produced significant changes in subjective and physiological measures, confirming its efficacy as a stressor. A significant increase in state anxiety was found between pre and post-assessment in the silence group, but not in the music group, indicating that post-stress recovery was faster in the musical group. Results suggest that music can ameliorate the subjective anxiety produced by fear of heights., QC 20160628

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