Laurie's Blogs.

As tends to happen, I had a patient that made me want to research and discuss the topic if whether electrical muscle stimulation (EMS) was of value in patients with peripheral nerve injuries, such as brachial plexus lesions.  

My patient was brought to see me from returning clients.  The dog was a rescued border collie cross that appeared to have had a previous brachial plexus injury.  While she was quite functional, her affected leg had significantly less muscle bulk, her carpus was restricted into flexion and pronation, her foot was flatter, and the whole of the leg appeared to be shorter in length.  She had been this way since she had been adopted just a year earlier.  The notes from the veterinarian acknowledged the same thought as to the presumed cause for the current clinical picture.  

In the end, I came up with a management plan for the owners, because she is so functional, and that is what was most practical seeing as these clients live over 12 hours away!!  However, when I was looking at the dog, the thought popped up into my head about EMS, and whether or not it would have any impact (now) or whether it might have in the acute stage.  So, that’s what the rest of this blog is about!!

Low and behold, I did find some research (Rat studies primarily) to validate the use of EMS following a peripheral nerve injury.  Here are some highlight:

1. The potential of using brief EMS (ES; 3 V, 20 Hz, 20 min) as a useful method to improve functional recovery for delayed repair (repair of nerve injury was delayed 2, 4, 12 and 24 weeks prior to repair) of peripheral nerve lesions.  Furthermore, brief EMS was capable of increasing brain-derived neurotrophic factor (BDNF) expression in the spinal cord.  (Huang et al 2013)

2. Electrical stimulation for 30 minutes (20 Hz pulse rate, 2 uA amplitude) immediately following crush injury is effective to promote nerve regeneration in a rat sciatic nerve model.  An elevated expression of brain derived neurotrophic factor (BDNF) in DRG sensory neurons of the EMS group was demonstrated five days post-injury. (Alrashdan et al 2010)

3. Electrical stimulation of chronically axotomized motor and sensory neurons (i.e. 3 months between nerve severance and nerve reattachment) is effective in accelerating axon outgrowth into chronically denervated nerve stumps and improving target reinnervation after delayed nerve repair. (Elzinga et al 2015)

Okay!  This is exciting.  I would say that with the next brachial plexus case that comes in, I will be grabbing my electrical muscle stimulation unit as part of the treatment regimen!  Of course, in those cases, we don’t know if the issue is a neuropraxia, an axonotmesis, or a neurotmesis, as the latter won’t heal if the ends aren’t surgically connected.  And of those nerve injury categories, you don’t know if you have an axonotmesis or neurotmesis until recovery does (or doesn’t) happen.  So, EMS is worth trying in the short term if you don’t have advanced diagnostic imaging to confirm.

What about my patient with the year-long PLUS injury?  Well, I’ll quote the Elzinga paper, “Functional recovery after peripheral nerve injury and surgical repair declines with time and distance because the injured neurons without target contacts (chronic axotomy) progressively lose their regenerative capacity and chronically denervated Schwann cells (SCs) atrophy and fail to support axon regeneration.”  So, I am still comfortable with my suggestions to the owners about ‘management’ of their dog versus trying to ‘fix’ the problem.

Okay… there you go!  I think we all learned something!

Until next time,  Cheers!

Laurie

References:

1.  Huang J, Zhang Y, Lu L, Hu X, Luo Z. Electrical stimulation accelerates nerve regeneration and functional recovery in delayed peripheral nerve injury in rats. Eur J Neurosci. 2013 Dec;38(12):3691-701.

2.  Alrashdan MS, Park JC, Sung MA, Yoo SB, Jahng JW, Lee TH, Kim SJ, Lee JH. Thirty minutes of low intensity electrical stimulation promotes nerve regeneration after sciatic nerve crush injury in a rat model. Acta Neurol Belg. 2010 Jun;110(2):168-79. 

3.  Elzinga K, Tyreman N, Ladak A, Savaryn B, Olson J, Gordon T. Brief electrical stimulation improves nerve regeneration after delayed repair in Sprague Dawley rats. Exp Neurol. 2015 Jul;269:142-53.