Postural stability using different neck positions in normal subjects and patients with neck trauma

Subjects with neck problems, such as whiplash injuries, often complain of d isturbed equilibrium and, in some instances, provocation of the neck positi on can elicit such problems. The importance of neck proprioceptors for main taining balance is gaining increased interest, moreover the function or mal function of the otoliths may disturb equilibrium in certain head positions. The aim of the study was to create a reference material for postural contr ol and its dependence on head position in healthy subjects and to compare t his with a set of patients with known neck problems and associated vertigin ous problems. A total of 32 healthy subjects (16 men, 16 women; age range 2 1-58 years) as well as 10 patients age range 27-62 years (mean 44 years) wi th neck problems and associated balance problems since a whiplash injury we re tested For postural control using the EquiTest dynamic posturographic mo del. The normal subjects were initially split into four age groups in order to estimate the effects of age on performance. The postural stability was evaluated for dependence of support sur face conditions (stable or sway-ref erenced), visual input (eyes open or closed) and head position (neutral, le ft rotated, right rotated, extended backwards or flexed forward) using anal ysis of variance (ANOVA) with Tukey's post hoc test in case of a significan t factor effect. As expected, visual cues as well as stable support surface improve postural stability (p < 0.001). Postural stability is statisticall y different in the head extended backwards condition compared with the othe r foul head positions (p < 0.001 in all cases) in both patients and control s. Eliminating this test condition from the analysis, only a slight (p < 0. 05) difference between head forwards and head turned left remained. This pa ttern of results remained if the normal subjects were only split into two a ge groups instead of Four. Finally, the patient group exhibited significant ly lower postural performance than all the groups of normal subjects (p < 0 .01), but none of the normal groups differed significantly from each other. It is concluded that the postural control system is significantly challeng ed in the head extended backwards condition in both normal subjects and pat ients with previous whiplash injury and persistent neck problems. The patie nt group differed statistically from all groups of normal subjects, This su ggests that neck problems impair postural control, and that the head extend ed position is a more challenging task for the postural system to adapt to. Whether this is due to utricular malpositioning, central integrative funct ions or cervical proprioceptive afferents is not within the scope of this s tudy to answer.