Postural Sway Biofeedback Training in Congenitally Blind Children

Abstract

The aim of this experiment was to determine whether or not congenitally blind children were able to control postural sway under auditory feedback and to examine the effect of such training in congenitally blind children. To assess postural control, a newly developed apparatus was used. Seven untrained congenitally blind children, aged 6 to 10 years, were tested on a force plate. When anteroposterior sway stayed within 10mm in the sagittal plane, no auditory feedback was given. If anteroposterior sway was more than 10mm, they were presented with a 500-Hz pure tone with a speaker. The width of 10 mm corresponded to approximately 80% of the amplitude of anteroposterior sway in each subject. Information about lateral sway was not provided. Time taken while anteroposterior sway exceeded and returned to the width of 10 mm was defined as the response time to a 500-Hz pure tone. Subjects stood for 60s on a force plate with arms held at the sides and feet together, and performed three trials for each training session. Training sessions were done once a week for five consecutive weeks. The results showed that the total time for which postural sway deviated from the width of 10 mm decreased as training continued. The results also indicated that the response time to the 500-Hz pure tone became shorter as training progressed. It is apparent that congenitally blind children changed their pattern of posture movements for postural correction; it may be associated with changes in postural strategy. Congenitally blind children may be refining their interpretation of auditory feedback and learning to integrate it in the control of posture. We will call the ability of the remaining sensory systems to control posture “nonvisual postural control systems”. In conclusion, it was found that postural sway biofeedback training was effective for the assessment of postural control in congenitally blind children.