Posturography: uses and limitations.

The field of posturography has been advanced by the development of computerized dynamic posturography, wherein a force platform has been combined with visual stimuli as a means of determining the relative importance of the various sensory inputs critical for balance, namely vision, somatosensation and vestibular sensation. When compared with other tests currently available for the assessment of vestibular function, computerized dynamic posturography is unique in that it assesses 'balance' rather than attempting to assess peripheral or central vestibular function more directly. This discussion focuses on the device manufactured by NeuroCom International, marketed under the trade name Equitest. The sensory organization portion of the test has been shown to be most useful in the assessment of patients with suspected vestibular disorders. This chapter reviews the current status of computerized dynamic posturography based on published material. The vestibular pattern on computerized dynamic posturography has been observed in patients with ongoing vestibulospinal deficits. Another pattern has been labelled 'surface dependence' or 'combined visual-vestibular deficit'. Data suggest that 2-3 weeks after loss of unilateral peripheral vestibular function, most patients lose their vestibular pattern. Thus, posturography can provide valuable information regarding the status of compensation for a peripheral vestibular deficit. Results from computerized dynamic posturography may disagree with those from other vestibular laboratory testing, which suggests that posturography tests a different aspect of vestibular function than that assessed by electronystagmography and rotational testing. Computerized dynamic posturography does not provide localizing or lateralizing information, nor any information regarding aetiology; it does provide functional information regarding how well an individual can use their balance and an indication of the importance of a patient's balance disturbance on their activities of daily living. Also, computerized dynamic posturography provides a functional measure that is helpful in predicting the benefit that patients may expect to receive from therapeutic intervention with physical therapy.