Dysfunction of the Central Nervous System in Chronic Whiplash and Tension-Type Headache

Background: Previous studies have indicated dysfunction of neuromotor control of neck muscles in chronic whiplash and tension type headache. This may implicate that the central nervous system is part of the pathophysiology of these deseases. For further verification, we used a laser tracking method for standardized and quantitative measurements of voluntary movements of head and hand. The hand was included as a presumed normal reference to the head movements. Methods: A new laser tracking instrument was used to monitor the ability of a test-person to track a reference point on the wall by a laser fixed to the forehead or held in the hand. The reference point moves in runs of a circle or a square at three different speeds 10, 20 or 30 cm/sec thus providing 6 runs for both head and hand per test-person. We used a 1x1x1 m set-up geometry. The data of each run was processed on-line. Groups of 22 patients diagnosed with chronic whiplash associated disorder, 19 patients diagnosed with chronic tension type headache and 37 control persons were tested. Findings: A small but highly significant dyscoordination of head movements was observed in both patients groups, and in whiplash also of the hand. Interpretation: We interpret the observed dyscoordination as a dysfunction of the neuromotor control of the implicated muscle groups, and suggest that the central nervous system is involved in the primary pathology of both chronic whiplash and tension type headache. Accordingly, we suggest a provisional term 'cervical dyssynergia' for these diseases. Funding Statement: Funding within institutions, no external funding. Declaration of Interests: None. Ethics Approval Statement: The protocol for this project was approved by the Scientific Ethics Committee of Region Hovedstaden as protocol H-6-2014-015 including directions for oral and written information and informed consent for all participants.