Original articleThe slow and fast components of postural sway in chronic neck pain
Introduction
Several studies have reported altered postural control in people with neck pain (Karlberg et al., 1995, Michaelson et al., 2003, Madeleine et al., 2004, Treleaven et al., 2005, Field et al., 2008). Most of these studies include assessment of the center of pressure (CoP) migration in unperturbed quiet stance on a force plate (Michaelson et al., 2003, Madeleine et al., 2004, Treleaven et al., 2005, Field et al., 2008). From the CoP migration data a wide range of outcome variables can be calculated. Different studies report different variables, for example CoP migration area (Michaelson et al., 2003), CoP displacement amplitude and path length (Madeleine et al., 2004) and energy of the CoP signal in anterior–posterior and medial–lateral directions (Field et al., 2008). The understanding of the neurophysiologic mechanisms reflected by the different variables from the CoP trajectory is, however, still poor. This may explain the scarceness of theoretical motives for the choice of variables, and the lack of standardization of outcome variables.
Several researchers have concluded that postural sway in quiet stance includes a slow and a fast component (Zatsiorsky and Duarte, 2000, Bottaro et al., 2005, Kiemel et al., 2006). The slow component of the CoP reflects a trajectory that approximates the gravitational line of the body’s center of mass (CoM) (Zatsiorsky and Duarte, 1999, Zatsiorsky and Duarte, 2000). The magnitude of the slow component has been attributed to noise in sensory information transmission and central processing when estimating the location and movement of the CoM (Kiemel et al., 2006). The fast component has been ascribed to restoring forces, generated by mechanical stiffness and tonic and phasic neural commands of the ankle muscles, in order to control CoM location (Bottaro et al., 2005). A method for decomposing the CoP trajectory into its slow and fast component has been presented by Zatsiorsky and Duarte (1999). This allows for a more in depth analysis of the postural sway mechanisms.
Our primary aim was to shed further light on the mechanisms behind increased postural sway in people with chronic neck pain. Therefore, the magnitude of the slow and fast CoP components were calculated to obtain information about possible alterations in the size of the sway that can be related to noise in the sensory system, and the amplitude of the forces controlling CoM. One group with chronic neck pain with traumatic origin, and another with non-traumatic origin, were compared with a group of healthy controls. Group comparisons were limited to pre-planned contrasts between each of the neck-pain groups and the control group.
A second aim was to investigate the associations between postural sway performance and self-ratings of health, functioning, kinesiophobia and symptoms. Such analysis may provide important clues to the mechanisms behind impairments as well as an indication of the clinical validity of the outcome variables.
Section snippets
Methods
This single blinded controlled cross-sectional study was performed at a vocational rehabilitation center (Alfta Rehab Center, Alfta, Sweden). The study was approved by the Regional Ethical Review Board in Uppsala. All participants gave their written consent to participate.
Results
All subjects completed the 30 s quiet stance test.
Fig. 1 shows representative examples of the CoP trajectories and the slow Ra and fast Tr components from one CON and one WAD subject.
Descriptive statistics for the CoP-based variables Ra and Tr area are shown in Fig. 2. Group difference was revealed for the slow component, Ra area (univariate ANOVA: F(2, 63) = 3.95, p = 0.02). The difference was significant between the WAD group and CON (p = 0.01), but not between NS and CON (p = 0.17)
Discussion
In the present study we found that subjects with WAD had an increased magnitude of the slow component of postural sway (Ra area) in quiet standing without vision. Greater magnitude of the slow sway component in the WAD group was associated with poorer self-rated functioning and more severe symptoms.
Conclusions
Decomposing the CoP signal into the slow and fast components may contribute to an enhanced insight into the mechanism behind altered postural sway in chronic neck pain. The results revealed that alterations are present for the slow (Ra) but not for the fast (Tr) component in WAD. This implies an aberration in sensory feedback or central processing of sensory input. The clinical validity of the assessment of the slow component was supported by the associations found between the magnitude of the
Competing interests
None.
Author contribution
UR conceived of the study and design, carried out the data collection, participated in the data processing and statistical analysis and drafted the manuscript.
MB conceived of the study and design and helped to draft the manuscript.
MD conceived of the study and design, carried out the data processing and helped to draft the manuscript.
All authors read and approved the final manuscript.
Acknowledgements
The authors would like to thank Nisse Larson for excellent engineering support and Maria Frykman for excellent administrative work. The study was partly funded by Alfta Research Foundation.
References (23)
- et al.
Body sway during quiet standing: is it the residual chattering of an intermittent stabilization process?
Hum Mov Sci
(2005) - et al.
Quantitative posturography in altered sensory conditions: a way to assess balance instability in patients with chronic whiplash injury
Arch Phys Med Rehabil
(2004) - et al.
A rating system for use with patient pain drawings
Pain
(1986) - et al.
Cervical vertigo
J Neurol Neurosurg Psychiatry
(2001) - et al.
Introduction to multi- and megavariate data analysis using the projection methods (PCA & PLS)
Umeå: Umetrics AB
(1999) - et al.
Standing balance: a comparison between idiopathic and whiplash-induced neck pain
Man Ther
(2008 June) - et al.
Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand) [corrected]. The Upper Extremity Collaborative Group (UECG)
Am J Ind Med
(1996) Measurement of pain
Lancet
(1974)- et al.
The development of the dizziness handicap inventory
Arch Otolaryngol Head Neck Surg
(1990) - et al.
Reduced postural control in patients with chronic cervicobrachial pain syndrome
Gait Posture
(1995)
Slow dynamics of postural sway are in the feedback loop
J Neurophysiol
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