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Psychological and physiological effects of neck pain treatment

Researcher: Jeanette Lynch

Supervisor: Professor Peter Drummond & Peter Finch

Date: April, 2011

Ethics Approval number: 2008/005

A localised burning sensation often appears in the suboccipital and cervical regions after radiofrequency lesioning for unilateral zygapophyseal joint pain. This was investigated to determine whether it was restricted to the treated area or extended to more distant sites. Whether psychological factors were involved was also investigated.

Pressure pain thresholds and sensitivity to standard heat and sharp stimulation of the medial and lateral aspects on the dorsum of the hands, feet, and both sides of the neck and forehead was assessed in 20 patients. Seventeen of these patients were also studied after lesioning of the medial branch nerves supplying painful zygapophyseal joints.

Before the treatment, heightened sensitivity to noxious heat was detected in the ipsilateral neck and on the contralateral side of the forehead. Sensitivity to the noxious heat stimulus decreased in the ipsilateral neck after the treatment but persisted in the contralateral forehead. Localized burning pain developed in the ipsilateral suboccipital region and neck in 47% of participants after the treatment. Following noxious heat stimulation of the ipsilateral forehead, heat after-sensations persisted in a greater percentage of patients with, than without, localized burning pain. Neither psychological issues nor the intensity of pain before treatment was associated with the development of burning sensations.

The pattern of heightened sensitivity to a noxious heat stimulus in untreated patients with chronic unilateral neck pain is consistent with aberrant central nervous system processing. Transient localized burning pain after radiofrequency treatment may be associated with sensitization of heat-sensitive second order neurons in the trigemino-cervical complex.