Zygapophyseal joint pain: thermal hypersensitivity and the development of neuritis following cervical radiofrequency neurotomy - psychophysical investigations.

Researcher Jeanette Lynch

Supervisors Professor Peter Drummond

Date: 11th June , 2010

The first aim of this study was to investigate the involvement of central sensitivity mechanisms in individuals with zygapophyseal joint pain. Secondly, neuritis, a localised, temporary burning side effect that sometimes appears after cervical radiofrequency neurotomy, was investigated to determine if it was restricted to the treated area or extended to more distant sites. Thirdly, it was hypothesized that depression, catastrophization and neck pain sensitivity would play a role in the development of neuritis. Touch thresholds, sensitivity to firm pressure, heat, cold, light touch and sharpness on the medial and lateral aspects on the dorsum of the affected and unaffected hands, feet, and both sides of the neck and forehead were investigated. Thirteen females and 7 males (mean age 55.3), primarily Caucasian older adults, were recruited from a pain clinic in Perth, Western Australia. . Seventeen participants were seen pre and post intervention. They were divided into two groups on the basis of whether they developed neuritis (n = 9) or not (n = 8). Thermal hypersensitivity was found to spread ipsilaterally to the foot, and contralaterally to the forehead. Neuritis was found in 47% of participants post cervical radiofrequency neurotomy with spread of thermal sensitivity to the forehead and increased cold sensation on the unaffected side in participants with no neuritis. There was no evidence to support the hypothesis that depression or catastrophizing or neck pain sensitivity was associated with the development of neuritis. Findings included a decrease in touch threshold on the hand for all participants post intervention, and participants with neuritis had abnormal sensation to touch on the unaffected side of the neck post radiofrequency. Conclusions drawn from these finding indicate that thermal hypersensitivity occurs in individuals with zygapophyseal joint pain, suggestive of aberrant central nervous system regulation.