Identification of a relationship between cervical spine function and rotational movement control

The cervical spine's stabilising function is generated by three interacting systems: an active system (the muscles), a passive system (capsules, intervertebral disks and ligaments) and a neutral system (the nervous system). Functional impairment induced by alteration of one or several systems can disturb movement control. Thus, a decrease in the quality of movement control could be directly linked to the cervical spine's state of impairment. The aim of the present study was to assess the relationship between cervical spine status (measured using a validated questionnaire) and the control of low-amplitude neck movements. Our starting hypothesis was that the more precise the movement, the faster it would be. We devised a test in which a sequence of rotational movements of the neck (to the left and to the right, alternately) was timed while monitoring the targeting of a laser beam (fixed to the right side of a pair of spectacles) on photodetectors placed directly in front of the subject and 30 degrees to the left and to the right of the body line. The test was performed using a system called the "Didren laser". Fifty-six subjects (of varying ages and both genders, classified as "disabled" or "healthy" according to the Neck Disability Index [NDI] questionnaire score) performed the test. Our results showed that: the score differed from one individual to another but was reproducible for a given subject; the score was age- and gender-independent; the highest scores (i.e. the slowest rotations) were generally produced by individuals classified as "disabled" in terms of the NDI questionnaire score. Our results led us to conclude that there is a relationship between functional disorders of the cervical spine and low-amplitude rotational movement control, although we were unable to define the exact nature of this relationship.