Change due to aging in equilibrium function on standing posture; sensory organization function and external disturbance stimulation due to postural deviation

For the dinical application of the Sensory Organization Test (SOT) in the Equi test system devised by L.M. Nashner, for the purpose of evaluating equilibrium function in the standing posture, we have conducted a basic analysis on SOT and prepared SOT databases. The subjects in this study were 19 healthy males and 26 healthy females between 20 to 85 years of age (average age: 46). We studied the characteristics of the sensory organization function of integrating vestibular sense information and inaccurate postural information in healthy persons by changing the sway gain of postural information input from bodily sense and visual sense, and by monitoring changes in equilibrium function due to aging. The results of this study, show that for elderly persons and patients with equilibrium function disorder, the condition of 1.0 sway gain (disturbance intensity), results in heavy psychological and physiological burdens and a danger of falling. Therefore we considered the optimum amount of disturbance stimulation to be 0.75 sway gain in all age groups. SOT using external disturbance stimulation caused by postural deviation reflected the aging alteration of equilibrium function, and it is a useful examination method for evaluating equilibrium disorder and the clinical conditions of elderly persons.