Non-Invasive Neuromodulation & The Balance-Impaired Patient
A person’s ability to balance can be impaired by conditions such as vestibular problems, cerebellar problems and Multiple Sclerosis. Through neuromodulation treatment the central nervous system can be stimulated to properly restore function and improve balance. Two non-invasive ways this can be achieved include galvanic vestibular stimulation (GVS) and tone burst vestibular stimulation. For this article we’ll be taking a look at GVS specifically.
GVS has been used for over a century as a means to discover and then look at the function of the vestibular system. The reaction of the vestibular system to a galvanic stimulus was first described by Purkinje in 1820. Historically the main use of galvanic stimulation was as a diagnostic test for the differential diagnosis of cerebellopontine angle lesions. It is no longer used diagnostically because of the invention of CT and MRI scans, which made it obsolete. It is, however, still very useful as a treatment tool to effectively stimulate the vestibular system in a non-invasive manner. GVS is a simple, safe and specific way to elicit vestibular reflexes. Yet, despite a long history, it has only recently found popularity as a research tool and is rarely used clinically.
An over-simplification of how GVS works is that usually a patient with a vestibular or ambulatory problem will tend to sway or lean one way (left or right) depending on which vestibular pathway is effected. The GVS stimulator has an anode lead (positive polarity) and cathode lead (negative polarity). The specific placement of the two leads behind both of the mastoid processes of the skull can stimulate the vestibular nerve. By placing the anode on the side opposite the way the patient tends to lean and the cathode on the same side as the lean you can effectively counteract the leaning tendency. The anode creates a “pulling” effect as the cathode simultaneously creates a “pushing” effect.
GVS produces a signal of head movement that has a potent effect on whole body motor control. In the trunk and limbs, it evokes reflex responses seen in the electromyogram and these result in a well-organized body movement.
For a look at the treatment process and how effective it can be check out this video link:
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