Can EMG results guage progression?

Does the presence or absence of fibrillations and positive short waves on an EMG have any relation to ongoing damage to
motor neurons? Mine showed a lot of giant potentials and decreased recruitment in my most affected limb, and borderline
readings in others, but no fibs or PSWs.

[CCF Neuro[P] MD, RPS]

Dear Jeffrey:

Yes, the EMG can denote progression.  Fibrillations are a sign of muscle denervation or loss of neuronal input to that motor unit within the muscle.  Postive sharp waves can mean similar things.  Motor disease itself can also show fibrillations, such as in ALS.  Giant potential usually are a sign of reinnervation of the muscle by a peripheral nerve.  As nerve endings are lost, new ones reinnervate the muscle and as they do, they recruit more motor units (or form connections to motor units).  This results in large potentials.  Decreased recruitment seems to come with age and also can be pathological depending on the medical history context.  It means that when increased electrical stimulation is given a nerve, there is less that what is considered to be normal, of muscle firings.  

Once you have large giant potentials, you always have large potentials.  So, basing the progression on these alone is not a good idea.  

Sincerely,

CCF Neuro MD