Mirror biofeedback rehabilitation after administration of single-dose botulinum toxin for treatment of facial synkinesis.

OBJECTIVE: The efficacy of facial biofeedback rehabilitation with a mirror after administration of a single dose of botulinum A toxin on facial synkinesis was examined in patients with chronic facial palsy. STUDY DESIGN: Prospective clinical study. SETTING: University hospital. SUBJECTS AND METHODS: The present study includes 8 patients with Bell palsy and 5 with herpes zoster oticus showing facial synkinesis. A single dose of botulinum A toxin was used as the initial process of facial rehabilitation. Patients then continued a daily facial biofeedback rehabilitation with a mirror at home. They were instructed to keep their eyes symmetrically open using a mirror during mouth movements. The degree of oral-ocular synkinesis was evaluated by the degree of asymmetry of eye opening width during mouth movements (% eye opening). RESULTS: After administration of a single dose of botulinum A toxin, temporary relief of facial synkinesis was observed in all patients. Patients were then instructed to continue the facial biofeedback rehabilitation with a mirror for 10 months. The mean values of the percent of eye opening during 3 designated mouth movements that included lip pursing /u:/, teeth baring /i:/, and cheek puffing /pu:/ increased significantly after 10 months when the effects of botulinum A toxin had completely disappeared. CONCLUSION: These findings demonstrate that facial biofeedback rehabilitation with a mirror after administration of a single dose of botulinum A toxin is a long-lasting treatment of established facial synkinesis in patients with chronic facial palsy.

Effects of optokinetic stimulation induced by virtual reality on locomotion: a preliminary study.

CONCLUSIONS: Exposure to a virtual environment for 20 min was sufficient to cause adaptive changes in locomotion in healthy subjects, suggesting that virtual environments might improve locomotor deviation in patients with unilateral labyrinthine defects. OBJECTIVE: Postural and locomotor control in patients with unilateral labyrinthine defects deviates towards the lesion side. The aim of this study was to examine whether active locomotion within a virtual environment can increase the functionality of rehabilitation. SUBJECTS AND METHODS: We examined the effects of optokinetic stimulation produced by a virtual reality environment on ocular movement and locomotor tracks in 10 healthy subjects. RESULTS: During the 20 min experiment, the mean locomotor deviation and the mean frequency and mean amplitude of optokinetic nystagmus during the last period of the experiment were significantly higher than those during the initial period.

Autonomic responses during motion sickness induced by virtual reality.

OBJECTIVE: To examine the development of subjective symptoms and heart rate variability (HRV) during motion sickness induced by virtual reality (VR). METHODS: Subjects were 10 healthy young volunteers. During VR immersion, subjects were immersed in a visual-vestibular conflict produced by VR. The levels of the subjective symptoms were assessed by Graybiel's and Hamilton's criteria. HRV was determined by measuring microvascular blood flow or electrocardiogram. RESULTS: Subjective symptoms evaluated by Graybiel's and Hamilton's criteria were gradually worsened during VR. Power spectrum analysis of HRV demonstrated a gradual increase in the low frequency but no change in the high frequency during VR. In this study, individual subjective symptoms were not correlated with the individual result of power spectrum analysis. CONCLUSION: These findings indicate that there was an increase in sympathetic nervous activity, but no change in parasympathetic nervous activity during motion sickness induced by VR. Given the large inter-individual variability and the reliability of subjective measures, it is not surprising that there is scarcely a relation between the subjective symptoms and the results of power spectrum analysis.

Effects of immersion in virtual reality on postural control.

In the present study, we examined the effects of the time lag between visual scene and the head movement in the virtual reality (VR) world on motion sickness and postural control in healthy volunteers. After immersion in VR with additional time lags (from 0 to 0.8 s) to the inherent delay (about 250 ms), the visual-vestibular conflict induced a slight motion sickness in experimental subjects, but no change was noticed in the body sway path with eyes open and closed. However, Romberg ratio of body sway path with eyes closed divided by that with eyes open after immersion in VR was significantly decreased in comparison with that before immersion in VR. Since Romberg ratio is an index of visual dependency on postural control, this finding indicates that the immersion in VR decreases the visual dependency on postural control. It is suggested that adaptation to visual-vestibular conflict in VR immersion increases the contribution of vestibular and somatosensory inputs to postural control by ignoring the conflicting delayed visual input in the VR world. VR may be a promising treatment for visual vertigo in vestibular patients with unsuccessful compensation by its ability to induce vestibular and somatosensory reweighing for postural control.