Using vibrotactile feedback of instability to trigger a forward compensatory ste

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J Neurol. 2007 Jul 25

Using vibrotactile feedback of instability to trigger a forward

compensatory stepping response.

Asseman F, Bronstein AM, Gresty MA.

Imperial College London, Dept. of Clinical Neuroscience, Charing

Cross Campus, Fulham Palace Road, London, W6 8RF, UK.

We evaluated the effectiveness of vibrotactile feedback to enhance

protective stepping with a view to developing a prosthesis for

patients with balance disorders. Subjects standing on a moving

walkway were exposed to an unpredictable, abrupt backwards

translation of the support surface that required a step response to

remain standing. The subjects were 15 normal young, 15 normal

elderly and 9 patients with either bilateral vestibular loss or

peripheral neuropathy. The initial passive displacement of the body

was recorded by a gyroscope placed on the leg which triggered a

vibration pulse to the trigeminal distribution on the forehead to

cue a forwards step. Stepping responses and postural sway, with and

without vibration feedback, were compared. Vibration produced

significantly shorter stepping reaction times only in the elderly

normals with naturally slower stepping. Patients did not benefit in

any way. We conclude that the effectiveness of vibration biofeedback

appears limited. Any enhancement of compensatory stepping might be

triggered by speeding the decision to step rather than by creating a

specific stimulus-response loop.