Exploration of somatosensory impairments in subjects with mechanical idiopathic neck pain: a preliminary study

Abstract

Objectives: The purpose of this study was to investigate the differences in pressure and thermal pain hypersensitivity between patients with acute and chronic neck pain and healthy subjects.

Methods: Five patients with acute neck pain, 7 patients with chronic neck pain, and 6 matched controls participated. Pressure pain thresholds (PPTs) were assessed over the supraorbital, infraorbital, mental, median, ulnar, and radial nerves; the C5-C6 zygapophyseal joint; the second metacarpal; and the tibialis anterior muscle by an assessor blinded to the subjects' condition. Head pain threshold and cold pain threshold (CPT) were measured over the cervical region and over the tibialis anterior muscle.

Results: The analysis of variance found significant differences between groups, but not between sides, for PPT over the supraorbital, mental, median, ulnar and radial nerves; the C5-C6 joint; the second metacarpal; and the tibialis anterior muscle: patients with chronic neck pain showed bilateral lower PPTs as compared with controls (P < .01). Patients with acute neck pain also showed lower PPT (P < .01) over the median and ulnar nerves. No significant differences between groups or sides for head pain threshold over the cervical area or the tibialis anterior muscle were found. Significant differences between groups, but not between sides, for CPT over the neck and the tibialis anterior muscles were found: CPT was also reduced in patients with chronic, but not acute, neck pain (P < .01).

Conclusions: We found widespread decreased PPT in patients with chronic, but not acute, mechanical neck pain as compared with controls. Patients with chronic neck pain also showed cold pain hypersensitivity as compared with patients with acute neck pain and controls. These results support the existence of different sensitization mechanisms between patients with acute and chronic mechanical insidious neck pain.