Auditory biofeedback during walking reduces foot contact pressure in a patient with congenital insensitivity to pain

Hereditary sensory and autonomic neuropathy (HSAN) includes genetic disorders that involve various sensory and autonomic dysfunctions. HSAN types 4 and 5 (HSAN-4 and -5) are characterized by congenital insensitivity to pain and thermal sensation. Orthopedic problems in HSAN-4 and -5 include destructive injuries. Studies on gait have shown greater speed and higher heel contact angular velocity in the patients compared to controls. Such a 'banging gait' may be the result of insensitivity to pain, and may be a cause of their injuries. To help prevent injuries, we are exploring the use of our novel auditory feedback device (Auditory Foot) that converts foot contact pressure into sound. In this paper, we report an immediate beneficial effect of auditory feedback in a participant with congenital insensitivity to pain. The participant was a 12-year-old girl with HSAN-4. We mounted the Auditory Foot device on both her feet and measured her foot pressure during gait as she walked on a treadmill. The peak pressure during the participant's gait decreased in both feet when auditory feedback was switched on. Patients with congenital insensitivity to pain tend to walk in a 'banging' way; increasing their awareness of their foot contact may improve their gait.