Vertical posture and head stability in patients with chronic neck pain.

OBJECTIVE To evaluate postural performance and head stabilization of patients with chronic neck pain. DESIGN A single-blind comparative group study. SUBJECTS Patients with work-related chronic neck pain (n = 9), with chronic whiplash associated disorders (n = 9) and healthy subjects (n = 16). METHODS During quiet standing in different conditions (e.g. 1 and 2 feet standing, tandem standing, and open and closed eyes) the sway areas and the ability to maintain the postures were measured. The maximal peak-to-peak displacement of the centre of pressure and the head translation were analysed during predictable and unpredictable postural perturbations. RESULTS Patients with chronic neck pain, in particular those with whiplash-associated disorders, showed larger sway areas and reduced ability to successfully execute more challenging balance tasks. They also displayed larger sway areas and reduced head stability during perturbations. CONCLUSION The results show that disturbances of postural control in chronic neck pain are dependent on the aetiology, and that it is possible to quantify characteristic postural disturbances in different neck pain conditions. It is suggested that the dissimilarities in postural performance are a reflection of different degrees of disturbances of the proprioceptive input to the central nervous system and/or of the central processing of such input.