J Neuroengineering Rehabil. 2006; 3: 9.
Published online 2006 May 4. doi:
Effect of step-synchronized vibration stimulation of soles on gait in Parkinson's disease: a pilot study
Peter Novakcorresponding author1 and Vera Novak2
1Department of Neurology, Boston University School of Medicine; 715 Albany Street, C315, Boston, MA 02118, USA
2Division of Gerontology2, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
Background
Previous studies have suggested that impaired proprioceptive processing in the striatum may contribute to abnormal gait in Parkinson's disease (PD).
Parkinson's disease (PD) is caused by a dopamine deficiency in the basal ganglia that results in characteristic motor abnormalities including postural instability and gait impairment. Short shuffling steps, slow walking speed, and increased stride variability characterize abnormal gait in PD.
Although PD is primarily a motor disease, accumulating evidence suggests that abnormal proprioception and kinesthesia contribute to the parkinsonian gait. PD patients have reduced sensation on the plantar feet [1] and impaired joint position sense [2], movement perception [3], and movement accuracy [4-6].
It has been proposed that an inadequate integration of sensory inputs at the striatum and a defective proprioceptive feedback underlie abnormal motor control movement in PD [6,7].
Sensory feedback is necessary for postural adjustments and facilitates control of compensatory stepping reactions evoked by postural perturbation [8-10]. Cutaneous, joint, and muscular mechanoreceptors provide the necessary proprioceptive inputs [11].
Mechanical stimulation of foot mechanoreceptors can be used to perturb the proprioceptive feedback and to assess its role in generation of parkinsonian gait. The foot pressure activates the plantar mechanoreceptors that mediate postural adjustment during the stance phases of the step [10].
Several studies explored the effects of mechanical stimulation upon static balance as a mean for proprioceptive feedback modulation. Subsensory mechanical noise applied to the soles has improved the quiet-standing balance in healthy controls [12] and in patients with diabetes and stroke [13]. This effect was attributed to enhanced proprioceptive feedback.
The effect of the suprathreshold stimulation is complex and depends on the frequency, amplitude, and location of the stimulation [14,15]. For example, during standing, the vibratory stimulation of the forefoot zones induces early electromyographic responses in the soleus muscle (mean latency 119 ms), followed by small forward center of pressure (CoP) displacement (mean latency 251 ms) and backward body tilt (mean latency 434 ms).
Vibratory stimulation of rear foot zones has a similar effect but with an opposite direction of the body tilt. Simultaneous activation of both forefoot and rear foot zones has no effect on body tilt but does cause CoP oscillations. These results imply that characteristic postural responses may be specific to the localization and character of a stimulus.
We hypothesized that a vibration stimulation of foot mechanoreceptors synchronized with the step improves gait in PD. In this study the step-synchronized vibration stimulation was used to enhance the proprioceptive input during walking in healthy and PD subjects.
The vibratory stimulus was delivered to the soles during the stance phase of the step, but not during the swing phase. Preliminary results were previously published as an abstract [16].
Study:
http://www.pubmedcentral.nih.gov/art...?artid=1471796