Irregular head movement patterns in whiplash patients during a trajectory task
From: Exp Brain Res. 2009 Oct 10
Chronic neck pain has been associated with disturbances in the sensorimotor control system in both non traumatic and whiplash related neck pain, such as postural stability disturbances, head and eye movement disturbances, erratic and irregular cervical motion patterns and stiffer, less flexible movement patterns. This points to centrally mediated somatosensory alterations with neck pain that may contribute to ongoing symptoms. Some motor impairments seem to particularly associate with a traumatic origin of the pain. Greater deficits in tests of head and eye movement control and decreased postural stability seem to distinguish whiplash associated disorder patients. Some of these deficits appear in association with the complaint of dizziness and neck pain intensity.
Patients with whiplash associated disorders have shown less accuracy in trajectory head motion compared to asymptomatic controls, which comply with clinical observations. The aim of this study was to investigate whether a trajectory head movement task can differ between whiplash associated disorders patients, chronic non traumatic neck pain patients and asymptomatic controls. Study groups included subjects with whiplash associated disorders (n = 35) with persistent neck pain after a car accident, chronic non traumatic neck pain (n = 45), and asymptomatic controls (n = 48). Head motion was recorded from an unsupported standing position using a 3D Fastrak device. A laser pointer was attached to the head and by moving the head the subjects were asked to trace a figure of eight displayed on the wall at three different paces (slow, moderate and fast). The motion signal was decomposed into 1 Hz frequency bands and angular velocity (deg/s) within each frequency band was calculated. Significantly higher angular RMS velocity was found in the whiplash associated disorders group compared to the two other groups for the slow paced test (3-4 and 4-5 Hz frequency bands) and the moderate paced test (3-4 Hz frequency band) indicating irregular and uncoordinated movements. Angular RMS velocity was associated with pain and dizziness, but only with severe symptom levels. In conclusion, irregular head movements during a complex task were found in the whiplash associated disorders group, indicating altered central sensorimotor processing. The irregularities were found within frequency levels observable to clinicians.
