Virtual Reality for Chronic Neuropathic Pain

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.

Inclusion Criteria:

- Presence of chronic neuropathic pain at or below SCI level for at least 6 months
following trauma or disease of the spinal cord;

- A pain intensity of at least 4 out of 10 in the numerical rating scale (NRS) in the
Neuropathic Pain Scale (NPS) test at both screening (baseline) and randomization
(pre-evaluation);

- Stable pharmacological treatment for at least 2 weeks prior to the study and
throughout the trial;

- Incomplete lesion (American Spinal Injury Association Impairment Scale, AIS B, C or D;
B= motor complete, sensory incomplete; C= sensorimotor incomplete with an average
strength of the muscles below the level of the lesion <3, D= sensorimotor incomplete
with average muscle strength >3);

- Cervical level of lesion (C2 to T1) with presence of pain in the upper extremities

Exclusion Criteria:

- Presence of severe pain of other origin, such as musculoskeletal pain

- Psychiatric or other neurological disorders

- Head injuries causing cognitive or visual impairment

- Severe vertigo

- Presence of potential risk factors for brain stimulation (TMS): history of seizures,
presence of surgically implanted foreign bodies such as a pacemaker, metal plate in
the skull, and metal inside the skull;

- Medically unstable