Sensorimotor incongruence exacerbates symptoms in patients with chronic whiplash associated disorders: an experimental study.

OBJECTIVES Incongruence between sensory feedback and motor output may serve as an ongoing source of nociception inside the CNS, and hence may contribute to the development of chronic whiplash associated disorder (WAD). It has been demonstrated that sensorimotor incongruence exacerbates symptoms and provokes additional sensations in patients with chronic pain. This study aimed to evaluate whether a visually mediated incongruence between motor output and sensory input aggravates symptoms and triggers additional sensations in patients with chronic WAD. METHODS Thirty-five patients with chronic WAD and 31 healthy controls were subjected to a coordination test. They performed congruent and incongruent arm movements while viewing a whiteboard or mirror. RESULTS All patients with chronic WAD (n = 35) reported sensory changes such as increased pain, tightness, loss of control, dizziness or feelings of peculiarity at some stage of the test protocol. No significant differences in frequency and intensity of sensory changes were found between the various test stages (P > 0.05). In the healthy control group, 18 (58%) subjects reported sensory changes at some stage of the test protocol, with the highest number during the incongruent mirror stage (n = 17), corresponding to the highest level of sensorimotor incongruence. The pattern of reported sensory changes during the congruent and incongruent stages was significantly different between both groups (P < 0.05). CONCLUSION This study demonstrates an exacerbation of symptoms and/or additional sensory changes due to reducing or disturbing the visual input during action, indicating altered sensorimotor central nervous processing and altered perception of distorted visual feedback in chronic WAD.