Using visual illusion to reduce at-level neuropathic pain in paraplegia

Abstract 

Neuropathic pain after spinal cord injury is not well understood and is difficult to treat. One possible cause is mismatch between motor commands and sensory feedback. This two-part study in five paraplegic patients investigated whether a visual illusion aimed to correct this mismatch reduces pain. In study 1, patients undertook three conditions: (i) virtual walking: with a mirror placed in front of a screen, patients aligned their own upper body with a film of a lower body walking. Patients imagined walking and ‘watched themselves’ walk; (ii) guided imagery; (iii) watching a film. One patient withdrew from virtual walking because of distress. For all patients, the mean (95% CI) decrease in pain (100mm VAS) was 42mm (∼65%) (11–73mm) for virtual walking, 18mm (4–31mm) for guided imagery and 4mm (−3 to 11mm) for watching the film. Mean (95% CI) time to return to pre-task pain was 34.9min (20.1–49.8min) for virtual walking; 13.9min (−0.9 to 28.8min) for the guided imagery and 16.3min (1.5–31.2min) for the film. To investigate its clinical utility, four patients underwent virtual walking every weekday for 3 weeks. Mean (95% CI) decrease in pain was 53mm (45–61mm) at post training and 43mm (27–58mm) at 3-month follow-up. Virtual walking may be a viable treatment for pain after spinal cord injury. A clinical trial seems warranted.

Keywords: Spinal cord injury, Physical therapy, Neuropathic pain, Paralysis, Visual input, Sensory-motor incongruence