The effect of neck pain on performance in tests of proprioception, cervico-cephalic kinesthesia and ocular motor function

This work investigated relationships between neck pain, cervical proprioception and ocular motor performance. Systematic literature reviews identified moderate quality evidence for greater cervical joint positioning errors (JPE) in the transverse plane among participants with whiplash, but low-to-very low quality evidence for participants with non-traumatic neck pain, and for other cervical and ocular tests. Limited low quality evidence indicated little correlation between performance across tests, questioning their construct validity for cervical proprioception. Test-retest studies established adequate intra-examiner reliability of a smooth-pursuit (SPNT) test, a novel, non-predictable ocular tracking test and of cervical JPE and cervico-cephalic kinesthesia tests. A cross-sectional study found impaired non-predictable ocular tracking performance in mechanical neck pain, compared with healthy participants. The construct validity of this, and of existing tests, was evaluated by examining convergence of correlation in their performance. In healthy participants, convergence between cervical JPE, cervico-cephalic kinesthesia and ocular tracking tests, indicated common neurological processes. In the neck pain group there was convergence only between the cervico-cephalic kinesthesia and ocular tracking tests. A theoretical model suggested that impaired cervical proprioception or cognitive functions underlie deficits in neck pain, while adaptations in vestibular gain or efference copy underlie the absence of impairment in the cervical JPE test