Investigating Mechanisms Underlying Spinal Cord Stimulation Efficacy Using Virtual Reality and Full Body Illusion

Investigating Mechanisms Underlying Spinal Cord Stimulation Efficacy Using Virtual Reality and Full Body Illusion

Investigating Mechanisms Underlying Spinal Cord Stimulation Efficacy Using Virtual Reality and Full Body Illusion

The study hypothesis is that spinal cord stimulation (SCS) combined with virtual leg illumination (provided through a wearable headset (OculusRift, OculusVR, Irvine, CA) and a custom-designed virtual reality leg scenario) will lead to controlled analgesia induction, boosting analgesic effects obtained with standard SCS treatments and will further be associated with changes in the perception of the affected body part.

Epidural spinal cord stimulation (SCS) is an approved treatment for truncal and extremity neuropathic pain. The mechanisms underlying the efficacy of SCS are unknown. Recent advances in cognitive neuroprosthetics using virtual reality allow for modulation of body perception and bodily experience, which has also been shown to modulate pain perception. The present research proposal plans to merge expertise in cognitive neuroprosthetics with neuromodulation techniques in order to test the analgesic properties of the combination of epidural spinal cord stimulation with a new system of multisensory stimulation based on virtual and enhanced reality (i.e., neuro-visual stimulation). The investigators propose to study this hypothesis prospectively in 25 patients with implanted SCS systems for the treatment of chronic neuropathic pain. Primary outcomes will be pain reduction (based on subjective, functional and physiological measures) and changes in body perception (based on subjective and objective measures). The present study will generate a proof-of-concept for the application of neuro-visual stimulation for the treatment of chronic pain and will form the basis for future NIH funding application.

Participants in this study will be adults who have already undergone implantation of SCS for the treatment of their pain conditions. The study involves no further treatment or intervention. Subjects will be approached for participation in this study during their routine postoperative clinical visit to the Center for Neuromodulation at the Ohio State University (OSU).All eligible patients will undergo a one-day visit for the virtual reality and full body illusion intervention. This research will also investigate leg embodiment and leg analgesic effects during SCS integrated with different patterns of virtual leg illumination.

a new system of multisensory stimulation based on virtual and enhanced reality (i.e., neuro-visual stimulation)

10 point Visual Analog pain rating Scale. Subjective pain perception will be measured by pain ratings on a 10cm visual continuous analog scale (VAS). Patients rate their pain, ranging from "no pain" (bottom part of the scale) to "the worst imaginable pain" (upper part of the scale) (Huskisson 1974). The pain reduction will be an average total of the pain scores taken at hours 1, 2, 3, 4, and 5.

Validated questionnaires developed by the collaborators (Swiss Federal Institute of Technology) will be used in order to investigate induced changes in leg perception and ownership. In particular, we will assess: 1) feeling of ownership towards the leg shown in the virtual reality set-up (leg ownership); 2) tactile sensations felt on the virtual legs, depending on the different conditions of SCS and visual stimulation. Patients will be asked to indicate how much they agreed with each item using a 7-point colored vertical Likert scale ranging from 0 (complete disagreement, the bottom extreme, red point) to +6 (complete agreement, the top extreme, green point).

Inclusion Criteria: Age 18-and older at the time of enrollment Patients carrying a diagnosis of CPRS type 125 or chronic refractory neuropathic leg pain following FBS4 Patients who have implanted epidural SCS The SCS implantation for at least three months prior to enrollment Patients with efficacious SCS as defined by ≥ 50% pain improvement after switching SCS from an OFF state to an ON state ('optimal' stimulation efficacy) Patients willing and able to provide informed consent Exclusion Criteria: Patients who are unable to effectively or efficiently communicate for example patients suffering from speech deficits (dysarthria, aphasia) or are non-English speaking. Patients with history of prior cranial surgery, significant brain lesions for example intracranial tumors, strokes etc. Non efficacious response to SCS <50% pain improvement with optimal stimulation parameters Evidence of untreated psychiatric disorders or drugs/alcohol abuse. History of seizures

Solca M, Krishna V, Young N, Deogaonkar M, Herbelin B, Orepic P, Mange R, Rognini G, Serino A, Rezai A, Blanke O. Enhancing analgesic spinal cord stimulation for chronic pain with personalized immersive virtual reality. Pain. 2021 Jun 1;162(6):1641-1649. doi: 10.1097/j.pain.0000000000002160.