Neuropathic pain (NP) affects 40 to 70% of people with SCI and is a very disabling clinical condition. The definitions of NP as well as its neurophysiology are widely discussed in the literature. Many treatment options have been offered, but provide limited effects, leaving people with SCI with a reduced quality of life.
Pain is a very complex experience that depends strongly on cognitive, emotional, and educational influences. Despite intensive investigations, the cause of neuropathic pain often remains unknown. A careful assessment of the pain including the use of tools to objectively measure pain will help with the diagnosis and the quantification of the damage. These tools include: 1) Laboratory testing that uses quantitative tests and measures objective responses in neurophysiology, sensory evoked potentials...etc.; 2) Quantitative sensory testing, that tests the perception of pain in response to external stimuli; 3) Bedside examination: physicians assessment on location, quality and intensity of pain; 4) Pain questionnaires, depending entirely on the subject's self-reported experience.
When spinal cord injury occurs, the spinal somatosensory circuit is thought to generate aberrant nociceptive impulses that the brain interprets as pain. Thalamic circuits may also serve as amplifiers of nociceptive signals. Sensory deafferentation after injury to the spinal cord produces extensive and long-lasting reorganization of the cortical and subcortical sensory maps. It has been suggested that pain and phantom limb sensations are the consequence of those cortical plasticity change. Therefore, strategies aimed at reversing or modulating the somatosensory neural reorganization may be valuable alternative approaches to neuropathic pain. Immersive virtual reality (IVR) is an emerging approach to the treatment of neuropathic pain conditions in SCI. Despite promising initial studies, IVR therapy has not yet been made widely available to individuals with SCI, because equipment is expensive and can be difficult for clinicians to use, especially those with limited experience with technology. However, with the development of 'plug and play', low-cost IVR devices such as the Oculus Rift, Gear VR and Google Cardboard, IVR no longer requires such specific technical knowledge. As a result, IVR is now a feasible and affordable treatment option for neuropathic pain.
The investigators believe that IVR neurorehabilitation exploits the idea of inducing activation in action observation, motor imagery, and processing systems, which in turn, should activate downstream cortical areas involved in movement and motor imagery. Also, perturbations of the somatosensory system associated with central pain can be reversed or modulated by employing motor imagery and related task execution combined with visual illusions. The investigators hypothesize that SCI patients using immersive IVR training will show improved reduction of neuropathic pain that will outlast the training sessions and transfers into daily life.
