Acuity of goal-directed arm movements to visible targets in chronic neck pain.

Abstract

OBJECTIVE: To evaluate end-point acuity in goal-directed arm movements in subjects with chronic neck pain, while taking the trade-off between speed and accuracy into account, and to evaluate associations between reduced acuity and self-rated characteristics. DESIGN: Single-blinded, controlled, comparative group study. SUBJECTS: Forty-five subjects with chronic non-traumatic, non-specific neck pain (n = 24) and whiplash-associated disorders (n = 21). Healthy subjects served as controls (n = 22). The groups were age- and sex-matched. METHODS: Subjects performed fast and accurate pointing movements to a visual target. Group differences in end-point variability, controlled for peak velocity, were evaluated. Associations between end-point variability and self-rated symptoms, functioning, self-efficacy and kinesiophobia were analysed. RESULTS: End-point acuity, controlled for peak velocity, was reduced for both neck-pain groups. Similar spatial error patterns across all groups indicated no direction-specific reduction. For both neck-pain groups, associations were found between end-point acuity and neck movement deficits, physical functioning and, in whiplash, also balance and pain. CONCLUSION: Acuity of goal-directed arm movements can be reduced in chronic neck pain. Associations between acuity and self-rated characteristics support the clinical validity of the results and indicate that impaired neck function contributes to reduced end-point acuity. The results can be of importance for characterization and rehabilitation of neck disorders.