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When to use NMES in BPI?
(email a question)
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Question:
There was a basic science research article (the subjects were mice) that stated that electrical stimulation of denervated muscles (as in Erbs’ Palsy infants until we see or feel activity) showed that it prevented sprouting of regenerating nerves. I have been hesitant to use e-stim for my Erbs’s infant remembering that the modality courses I have taken cautioned no e-stim to denervated muscles. I was happy to see that TES is recommended rather than e-stim as there was also another article that stated the only positive results were with low intensity, long duration stimulation over night (as is noted in your network) and it was noted that this type of stimulation had positive results probably from the induced increased circulation. Please comment.
Answer:
You are exactly correct on holding off on NMES until the nerve is fairly well regenerated. The animal study was Tam S.L. et al, “Increased Neuromuscular Activity Reduces Sprouting in Partially Denerved Muscles.” The Journal of Neuroscience, 2001;21(2):654-667. There was relationship to the extent of denervation and the amount of damage, so waiting for reasonable movement return makes sense. In contrast, TES seems to stimulate growth of both nerve and muscle in the denervated subject.
The other reason to avoid the classical forms of NMES in denervation is that this form of electrical stimulation does not produce a normal recruitment pattern in the target muscle.
Gregory CM & Bickel CS, “Recruitment Patterns in Human Skeletal Muscle During Electrical Stimulation”, Physical Therapy, 2005; 85:359-364. The argument for NMES advanced in this article is theoretically sound, but the problem in situations of partial denervation is that NMES leads to a greater amount of fatigue for unit of work. This may be helpful if you are a weight lifter. In partial denervation, it rapidly leads to overwork damage. We see fatigue clinically when the applied current has to be increased to achieve the same amount of muscle contraction.
The EMG Triggered Stimulation avoids the overwork problem by using the child’s brain to control the stimulation. The EMG signal increases when the child attempts to move and then the stimulation helps complete the movement. The term for this is “Neurofacilitation”. The contraction produced is smooth and comfortable and takes LESS current to achieve the same response. It is 21st century NMES. It avoids overwork fatigue because if the nerve is fatigued, the stimulation will not fire.
The following are 2 animal articles that address the issue of nerve regeneration with low-level electrical stimulation.
Roman G.C. et al, “Stimulation of Sciatic Nerve Regeneration in the Adult Rat by Low-Intensity Electrical Current.” Exp Neurol 1987; 98:222-232
Rusovan, K.M. “ Magnetic Fields Stimulate Peripheral Nerve Regeneration in Hypophysectomized Rats.” Neuroreport, 1992; 3:1039-1041
Remember that all current flow creates a magnetic field and all magnetic fields cause current flow....a true “chicken and egg” example. These early studies have been validated, but the possibilities they raise have not yet led to more clinical studies. There is also a wide literature on the effect of various forms of electrical stimulation to raise blood flow...in the absence of muscle contraction.
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