Dynamic posturography in evaluating human equilibrium

• Equilibrium assessment by means of posturography can be performed ina dynamic fashion, meaning that the environment does not remainstable during the test. In the EquiTest dynamic posturography version, the support surface and the visual surround are movable, actively or in response to body movements. Equilibrium ability is investigated in a sensory organ1zat1on (SO) part where six different combinations of vision (normal, sway referenced and absent) and support surface conditions (stable and sway referenced) are given. Postural responses to sudden translations and tiltings of the support surface are investigated in a movement coordination (MC) part. standardized dynamic posturography was utilized to assess equilibrium performance in different groups of subjects. In twentynine elderly healthy subjects, dynamic posturography evaluated the influence of age on equilibrium parameters. A decline compared to younger age groups was f~und. Fifteen of the elde:ly s~bjects underwent physical exerc~ses two hours a week dur~ng n~ne weeks, the remaining subjects served as controls. Significant improvement attributable to the exercises was found in one out of six so conditions and two out of twelve clinical equilibrium tests. In twenty-eight subjects with polyneuropathy, impaired equilibrium was found in so and delayed reactions to sudden support surface movements -w~re found in MC. Comparing dynamic posturography with neurological measures of polyneuropathy unveiled correlations between subjective clinical scoring and latencies to forward translations in MC and to equilibrium performance in three out of six so conditions. In seven subjects with chronic toxic encephalopathy due to industrial solvent exposure, impaired equilibrium was found in four out of six so conditions, although MC was normal. In thirteen healthy subjects, acute low level alcohol ingestion caused balance disturbances in SO conditions with abs7nt visual cues. In addition to disturbances of ocular smooth pursu1t and visual suppression of the vestibuloocular reflex in elevenabstinent chronic alcoholics, deteriorated equilibrium performance was found in four so tests out of six. Postural reactions to both sudden translations and tiltings of the support surface were found to be marred, in spite of normal nerve conduction velocities. The EquiTest dynamic posturography apparatus was cont:olle~ by amenu-driven interface constructed at the department, ~n wh~ch the user may expose the subject to arbitrary movement~ ~f the.supp~rt  surface and the visual surround. The effects of v1s1on, d~rect~on and amplitude on postural reactions to su~den support surface translations were evaluated. Absence of v1sual cues caused more rapid correction maneuvres, but the translation direction did ~ot influence the reactions. Postural responses reflected translat1on amplitudes.

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MEDICIN

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