Sensory substitution therapy using a tilt perception adjustment device (TPAD) for patients with bilateral vestibulopathy
tilt perception adjustment device
Bilateral vestibulopathy is characterized by bilateral functional impairment of the peripheral vestibular system. The usual symptoms are persistent unsteadiness and oscillopsia during head and body movements. It has been reported that sensory substitution therapy, that is, vestibular rehabilitation using a sensory substitution device, which transmits other sensory information to a stimulator as a substitute for defective vestibular information, might be effective in patients with bilateral and unilateral vestibulopathy. Recently, we developed a new wearable device, TPAD (tilt perception adjustment device), that transmits vibratory input containing head-tilt information to the mandible as a substitute for defective vestibular information.
We assessed the patient using the dizziness handicaps inventory (DHI), gait analysis, and visual/somatosensory dependence of postural control in the patients with unilateral vestibulopathy. Three months after therapy in patients with unilateral vestibulopathy, the DHI and walking speed improved even when the subjects were not wearing the TPAD. Moreover, the index of the visual dependence of posture control that was evaluated by posturography with/without foam rubber in the eyes open or closed condition decreased. The findings suggested that the sensory vibratory substitution with a TPAD for defective vestibular information induced brain plasticity related to sensory re-weighting to reduce the visual dependence of posture control, resulting in the improvement of dizziness and imbalance even while not wearing the TPAD in vestibulopathy patients.
We then investigated the effects of sensory substitution therapy using a TPAD in patients with bilateral vestibulopathy and normal subjects. Three months after sensory substitution therapy in patients with bilateral vestibulopathy, the DHI and area with eyes closed measured by posturography improved even when the subjects did not wear a TPAD. However, the gait parameters improved only under the condition of wearing a TPAD. These findings suggest that sensory vibratory substitution with a TPAD might serve as temporary replacement for defective vestibular information in patients with bilateral vestibulopathy. Moreover, wearing of the TPAD improved posture control under the eyes-closed condition with foam rubber measured by posturography in normal subjects. TPAD might be applicable as a wearable device for improving posture control, not only in patients with bilateral vestibulopathy, but also in those with presbyvestibulopathy.
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