Cervical Radiofrequency Neurotomy Reduces Central Hyperexcitability and Improves Neck Movement in Individuals with Chronic Whiplash

Abstract

Objective. This study aims to determine if cervical medial branch radiofrequency neurotomy reduces psychophysical indicators of augmented central pain processing and improves motor function in individuals with chronic whiplash symptoms. Design. Prospective observational study of consecutive patients with healthy control comparison. Setting. Tertiary spinal intervention centre in Calgary, Alberta, Canada. Subjects. Fifty-three individuals with chronic whiplash associated disorder symptoms (Grade 2); 30 healthy controls. Methods. Measures were made at four time points: two prior to radiofrequency neurotomy, and 1- and 3-months post-radiofrequency neurotomy. Measures included: comprehensive quantitative sensory testing (including brachial plexus provocation test), nociceptive flexion reflex, and motor function (cervical range of movement, superficial neck flexor activity during the craniocervical flexion test). Self-report pain and disability measures were also collected. One-way repeated measures analysis of variance and Friedman's tests were performed to investigate the effect of time on the earlier measures. Differences between the whiplash and healthy control groups were investigated with two-tailed independent samples t-test or Mann-Whitney tests. Results. Following cervical radiofrequency neurotomy, there were significant early (within 1 month) and sustained (3 months) improvements in pain, disability, local and widespread hyperalgesia to pressure and thermal stimuli, nociceptive flexor reflex threshold, and brachial plexus provocation test responses as well as increased neck range of motion (all P < 0.0001). A nonsignificant trend for reduced muscle activity with the craniocervical flexion test (P > 0.13) was measured. Conclusions. Attenuation of psychophysical measures of augmented central pain processing and improved cervical movement imply that these processes are maintained by peripheral nociceptive input.