[Changes in posture in whiplash evaluated by static posturography].

Analyzing vestibular-spinal reflex by recording changes in the pressure center over time, static posturography provides precise, repeatable information regarding a person's posture and subsequent postural strategy. Moreover, using the detected postural pattern, this can presage likely genesis of problems in equilibrium. The purpose of the present work was to evaluate posturographic findings in subjects with chronic or persistent whiplash (WL)-induced disequilibrium in order to determine any clear postural pattern able to indicate the likely genesis of the disorder. Fifty young subjects were selected for the study: 28 (6 females) affected with equilibrium problems resulting from WL-type cervical strain and 22 (5 females) normal, age compatible controls (C) (mean age of the groups: WL = 37 +/- 14.3; C = 32.4 +/- 6.7; p = n.s.). The results obtained were statistically processed with a personal computer and specific software (Windows-SPSS). In the analysis of the means (T-test and ANOVA analysis of variance) p < 0.05 was considered significant. In the WL group there was an increase in the antero-posterior axis oscillation frequency as compared to the control group. This is indicated by the FFTY parameter in tests performed both with eyes open and closed. Likewise, in both tests, there was a decrease in the LFS value, a parameter correlating length with surface. The surface was increased in the WL group as compared to group C although this increase was significant only when the test was performed with eyes closed. In addition, the average velocity and standard deviation of velocity increased in the WL group but this was only statistically significant when the eyes were open. The results obtained in the present study show that whiplash victims show an increase in antero-posterior oscillation frequency at the pressure center, as found in the open and closed-eye tests. This suggests that in WL subjects there is an evident disturbance of the fine postural system, leading to an increase in the surface parameters, tracing length and a decrease in LFS function. The onset of this partial postural decompensation can be seen in: a) decrease in fine static postural control which is reflected in an increase in body surface oscillation; b) an increase in energy consumption to maintain orthostatism as revealed in the decreased LFS. In conclusion, it appears reasonable to assume that cervical proprioceptive alterations play a preeminent role in the genesis of whiplash-induced chronic postural instability. This would result in an attempt to vary the physiology from an ankle to a hip strategy; incomplete manifestation of this new posture would cause the feeling of instability mentioned by the patients and documented by posturography.