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Neck-shoulder pain is common in the general population and causes individual suffering as well as large costs for the society. Despite substantial efforts, there is still a shortage of methods for objective diagnosis and effective rehabilitation of such disorders. Thus, there is a great need to develop and evaluate new methods for these purposes. From clinical observations and recent research it has become evident that sensorimotor control can be impaired in people with neck-shoulder pain and may play a role in the pathogenesis of these disorders. In this thesis, precision of goal-directed arm movements, a previously unstudied class of movements in neck-shoulder pain, was studied.

The main aim of the thesis was to investigate if people with chronic neck-shoulder pain have a reduced acuity of goal-directed movements of the upper extremity. A second aim was to study associations between reduced movement acuity and symptoms and self-rated characteristics.

Upper limb repositioning acuity was assessed in blindfolded subjects performing tests of active, ipsilateral position-matching of two target positions (long and short) in movements constrained to horizontal-adduction of the shoulder. Reduced repositioning acuity, suggesting impaired shoulder proprioception, was found for both subjects with whiplash associated disorders (WAD) and non-specific neck-shoulder pain (NS). The degree of reduced acuity was shown to correlate with self-ratings of various health concepts, functioning and pain. A conspicuous finding was that there was lack of correlation between short and long target errors, along with the fact that associations between repositioning acuity and symptoms and self-rated characteristics was primarily found for the short target position.

To further investigate the possible mechanisms underlying the disassociation between long and short target movement control, the association pattern between the outcome of several variants of ipsilateral position matching and velocity-discrimination tests, were studied. It was found that the perception of limb position in position-matching of short target locations appears to be predominantly based on movement velocity, whereas perception of limb position in movements to longer target locations may rely on a location-based perception mechanism.

To extend the research on reduced upper extremity proprioception in neck-shoulder pain to a more natural movement situation, acuity of goal-directed pointing including full vision and 3D multi-joint movements was investigated in WAD, NS and healthy controls subjects. The results revealed a reduced acuity for both neck-pain groups. Moreover, distinct associations between end-point acuity and neck movement problems, limitations of some physical functions and, in WAD; some aspects of pain, were revealed.

The findings demonstrate that the precision of upper limb movements can be reduced in chronic neck-shoulder pain. Substantial associations with symptoms and self-rated functioning suggest a clinical relevance of acuity measures of goal-directed arm movements. The findings indicate that tests of sensorimotor control can provide objective measures that may be useful in biopsychosocial profiling and characterization of subgroups of patients with chronic neck-shoulder pain, and that training target control of goal-directed movements should be considered in rehabilitation programs of people with these disorders.

Chronic neck pain is a widespread problem that causes individual suffering as well as large costs for the society. The knowledge about the pathophysiology is poor and therefore specific diagnosis and causal treatment are rare. Important knowledge for characterization of the disorders has been gained from research on sensorimotor functions in people with neck pain. Moreover, rehabilitation regimes including sensorimotor exercises indicate promising results.

The main objectives of this thesis were to extend the knowledge on sensorimotor dysfunctions in chronic neck pain, and to develop a new exercise method for improving sensorimotor functions of the neck. The studies focused on aspects of postural control and movements of the arm and neck. These are vital functions for many activities of daily living. People with chronic (>3 months) neck pain were compared to healthy controls (CON). Neck pain related to trauma was referred to as whiplash associated disorders (WAD), while neck pain without association to trauma was referred to as non-specific (NS).

Arm-functioning was assessed in a pointing task. WAD and NS had reduced pointing precision compared to CON. The reduced precision was associated with self-rated difficulties performing neck movements, physical functioning, and in WAD, also pain and balance disturbances.

Postural control was assessed in quiet standing on a force platform without vision. The center of pressure signal was decomposed into it’s slow and fast components. WAD and NS were compared to CON. The results revealed an effect of age on the magnitude of the fast sway component, but no effect of group. The magnitude of the slow component was elevated in both WAD and NS. This increase was associated with self-rated balance disturbance, arm-functioning, difficulties to run and sensory alterations in WAD, while in NS, the increase in the slow sway component was associated with concurrent low back pain.

Neck movements were assessed in a cervical axial rotation test with maximal speed. In total 8 variables representing basic kinematics, including variables reflecting movement smoothness and conjunct motions were calculated. NS were compared to CON. Linear discriminant modelling indicated Peak Speed and conjunct motions as significant classification variables that together had a sensitivity of 76.3% and specificity of 77.6%. Retest reliability was good for Peak Speed but poor for the measure of conjunct motions. Peak Speed was slower in NS compared to CON, and even slower in a sub-group of NS with concurrent low back pain. Reduced Peak Speed was associated with self-rated difficulties performing neck movements, car driving, running, sleeping disturbances and pain.

The clinical applicability of a novel method for neck coordination exercise was assessed in a pilot study on persons with NS. The results supported the applicability and indicated positive effects of the exercise: reduced postural sway in quiet standing and increased smoothness in cervical rotations. Indications on improvement in self-rated disability and fear of movement were seen at six months follow up.

In conclusion, sensorimotor functions can be altered in chronic neck pain, particularly in neck disorders with concurrent low back pain and WAD. The discriminative ability and clinical validity displayed in pointing precision, postural sway and cervical axial rotation speed imply that such tests can be valuable tools in the assessment of chronic neck pain patients, and for selecting and evaluating treatment interventions. Indications of improvements seen in the pilot-study support a future RCT.