ACTUAL AND PERCEIVED POSTURAL SWAY DURING BALANCE SPECIFIC AND NONSPECIFIC PROPRIOCEPTIVE STIMULATION

A group of patients with balance complaints (n = 16) was compared with a group of normal subjects (n = 17) by means of posturography, subjec tive assessments of balance, anxiety and unsteadiness when standing on a force platform with eyes closed. Postural instability was induced b y vibratory stimulation of the calf muscles (20, 40, 60, 80 and 100 Hz ). As a control condition, the arm (biceps) was stimulated at similar frequencies. In order to control for arousal, blood pressure and heart beat were assessed. Furthermore, questionnaire responses on psycholog ical measures were collected. Results showed clear differences between the groups in terms of imbalance and self-reports. However, the 2 gro ups displayed similar increases of imbalance during calf stimulation a nd no increase during arm stimulation. Patients generally rated less i ncrease of unsteadiness when the calf was stimulated than did the cont rols. No differences in arousal were found between the groups or withi n conditions. Results are discussed in terms of the proposed desynchro ny between symptoms and complaints.