The latest literature on whiplash injuries has been focused on the role of facet joint injury as the cause of pain and disability. One piece of information that has led researchers in this direction is the prominent role of proprioceptive dysfunction in whiplash-related dizziness.
(Proprioception is that part of the nervous system responsible for communicating to the brain the body's movement and position. Proprioceptive receptors in the cervical spine play a key role in the Posture Control System (PCS)—the mechanism by which the body maintains balance and equilibrium.)
A new study has added to our knowledge of this complex relationship by comparing a group of 75 whiplash patients to three other groups of control subjects: 20 patients with vertigo caused by central nervous system disorder, 20 patients with Meniere's disease (a disorder of the inner ear), and 30 healthy subjects.
The stated objective was to see how these different conditions influenced the results of a relatively new test called the Smooth Pursuit Neck Torsion test (the SPNT)—a test specifically designed to detect and diagnosing cervical-related dizziness. A secondary finding of the study, however, was that there are significant differences in the origins of dizziness between the different groups of patients.
The SPNT works by comparing the movement of the subject's eyes on a target in a neutral position and one in which the neck is experiencing torsion. A difference in eye movement between the torsion and neutral positions indicate that the Postural Control System is experiencing interference in the cervical spine.
The only subjects that showed indications of cervical proprioceptive interference were the whiplash patients, and these results were highly significant statistically. The authors conclude that this proprioceptive interference may be caused by damage to the facet joints of the cervical spine—just as other researchers have recently concluded.
Also, the SPNT test may be a good objective test to provide evidence of whiplash injury:
"Neck torsion had no effect in subjects with brain stem or vestibular disorders, or an intact balance system, unlike that in patients with WAD [whiplash-associated disorder] with dizziness and, to a lesser extent, in patients with WAD without dizziness. The SPNT test therefore seems to be useful for diagnosing cervical dizziness, at least in patients with WAD having symptoms of dizziness, because it has a high sensitivity and specificity."Tjell C, Rosenhall U. Smooth pursuit neck torsion test: a specific test for cervical dizziness. The American Journal of Otology 1998;19:76-81.