Sensitivity and specificity of platform posturography for identifying patients with vestibular dysfunction

Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis 55455.

Sensitive and specific measures are needed to identify patients with vestibular impairments. The purpose of this clinical perspective is to describe the sensitivity and specificity of dynamic and static platform posturography for detecting vestibular disorders. The sensory organization test (SOT) of dynamic posturography (EquiTest), the motor "perturbation" test, and Romberg's tests on a static (fixed) force platform each had over 90% specificity. This finding means that nearly all of the subjects who should have tested negative, did test negative on each type of assessment. The sensitivity of the SOT was evaluated across five studies involving a total of 836 patients with peripheral vestibular deficits (PVDs). Abnormalities in the SOT were detected in only 40% (n = 338) of the cases. Static platform posturography sensitivity was evaluated across six studies involving a total of 571 patients with PVDs, and abnormalities were detected in 53% (n = 302) of these cases. Tests of spontaneous and positional nystagmus and the horizontal component of the vestibuloocular reflex (VOR), by comparison, detected PVDs in 48% of 798 patients with suspected vestibular impairment. For patients with vestibular deficits associated with central nervous system disease, a total of 389 cases were identified in five studies and SOT abnormalities were found in 54% (n = 209) of these cases. The motor perturbation test was abnormal in 35% (n = 41) of 119 patients with central vestibular disease. In conclusion, the sensitivity of static posturography appeared to be slightly better than that of dynamic posturography for detecting PVDs, but the level of sensitivity for each posturography test, as well as for tests of horizontal VOR function, was considered to be low. Combining either type of posturography with other tests of vestibular function, however, increased the overall sensitivity of detecting vestibular deficits to 61% to 89%. It was concluded that dynamic and static platform posturography as well as tests of VOR function lack adequate sensitivity to detect vestibular impairment when applied in isolation. Posturography appears to detect vestibular deficits in some patients who had normal VOR assessments and, therefore, provides supplemental rather than redundant information about vestibular dysfunction.

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