Discrimination between patients with acoustic neuroma and with peripheral vestibular lesion by human posture dynamics.

A group of normal subjects (n = 17) was compared with two groups of patients, either with vestibular neuritis (n = 18) or with acoustic neuroma (n = 35) by means of posturography when stance was perturbed with vibrators attached to the calf muscles. Dynamic control of human posture was quantified by means of system identification, and the characteristic parameters of swiftness, stiffness, and damping of a transfer function from vibration to force platform response were used for further comparison. Fisher linear discriminant analysis was used to distinguish sets of parameters characteristic of each disease. Hence it was possible to distinguish the vestibular neuritis group both from the normal group (p < 0.01), and from the patients with acoustic neuroma (p < 0.001). The normal group was characterized by a different postural performance, with higher swiftness and stability parameters (stiffness, damping) than those of the patient groups. These findings indicate that there are differences in the dynamic control of posture between the two patient categories, which may require the development of differentiated rehabilitation programs.