A novel device that stimulates the vestibular system may benefit patients with Parkinson's disease, particularly those with balance and gait problems, a preliminary study suggests.
Senior author, Filip Bergquist, MD, University of Gothenburg, Sweden, explained to Medscape Medical News that the concept was based on the idea of "adding noise to the nervous system, which seems to make it work better to compensate."
He noted animal studies show that stimulating the vestibular system leads to neurotransmitter release in the basal ganglia, causing an effect similar to that of giving levodopa to patients with Parkinson's disease.
The current small pilot trial was conducted to see whether the same effect could be produced in patients with Parkinson's disease themselves.
The study, published in the journal Brain Stimulation, involved 10 patients who wore external electrodes behind their ears to stimulate the vestibular system. "The stimulation used was very gentle — 300 to 500 microamps, which is below the threshold needed for skin sensation so the patient doesn't feel anything, and the brain doesn't interpret it as a change in posture," Dr Bergquist commented.
The study was conducted on 2 different days, and vestibular or sham stimulation was administered in a double-blind, placebo-controlled, crossover design. Patients were block-randomized to active treatment or sham stimulation on the first test day, with the other treatment given on the second test day.
Patients were instructed not to take Parkinson's medication in the 12 hours before the study so the stimulation could be evaluated without the effect of medication. Patients were then given a single oral 200-mg dose of levodopa to investigate the effect of the stimulation while receiving medication.
Motor symptoms and balance were evaluated by using the Unified Parkinson's Disease Rating Scale, Posturo-Locomotor-Manual movement times, static posturography, and force plate measurements of the correcting response to a balance perturbation.
Results showed that the patients did not detect when stimulation was active or sham, but the active stimulation was associated with increased nausea after levodopa in two patients.
Greater Effect Off Medication
Efficacy results suggested that active stimulation improved both static and dynamic balance, with a greater effect off mediation than on medication. However, improvements of overall motor symptoms were not clearly demonstrated.
Dr Bergquist explained to Medscape Medical News that it is thought the vestibular stimulation causes an inhibitory effect — perhaps through the release of GABA — on the substantia nigra, which is overactive in Parkinson's disease.
He noted that previous Japanese studies have also suggested that vestibular stimulation may be associated with improved cognitive abilities.
Commenting on the study for Medscape Medical News, Michael S. Okun, MD, professor, UF Center for Movement Disorders and Neurorestoration, Gainesville, Florida, and medical director of the National Parkinson Foundation, said that although stochastic vestibular stimulation is a "novel potential approach" to treatment of balance in Parkinson's disease, "we need to be cautious about this study, which included only 10 patients.
"Many similar interventions for walking and balance in Parkinson's disease have proven to be effective for only small subsets of Parkinson's patients but not applicable to the general population of sufferers," Dr Okun said. "What would be very interesting is to understand how it might work, and to use this information to guide the field to more universal treatments for balance dysfunction in Parkinson's disease."
Dr Bergquist agreed that the current pilot study represents very preliminary findings. "We haven't shown anything clinically significant yet. But we have learnt from this pilot study that the best group of patients in which to study this technology is probably those with Parkinson's disease who have balance and gait issues."
He added that postural symptoms in Parkinson's disease are not well treated with current dopaminergic medication. "This device may provide a new approach that does not rely on dopaminergic transmission. That is very attractive."
A larger study is now planned in which patients would wear the stimulation device at home for a few weeks.
In the paper, the researchers conclude: "One of the most devastating complications to Parkinson's disease is falls. This problem increases and becomes less treatment responsive as the disease progresses. Although the dynamic balance test used here is a surrogate marker, and responses were not completely normalized by SVS [stochastic vestibular stimulation], PD [Parkinson's disease] patients who report falls could potentially benefit from long term use of SVS."
The study was supported by the Swedish Research Council, and in part through the NASA Cooperative agreement with the National Space Biomedical Research Institute and the National Institutes of Health.
Brain Stimul. Published online December 3, 2014. Abstract
http://www.medscape.com/viewarticle/841476?src=wnl_edit_tpal&uac=66422BV
No comments:
Post a Comment