What is an EMG for?

[SadsackinCali]

At my Neuro appt. today, I was told by my Neuro that an EMG and nerve conduction tests were only performed to see if a person has a pinched nerve. That didn't sound right to me. Is he right or should I be seeking a second opinion?

He said that if after I have seen the psychiatrist my problems aren't resolved, the only thing he can do is send me to UCLA or San Fran. Shouldn't that be done only after certain tests have been performed locally? I'm confused and not sure that I trust this Dr.

Allison

 

[vickim]

I don't know if an emg can diag nos a pinched nerve but I have had 3 emg/nvc and my neuro told me I had muscle weakness and neuropathy.
I would go to the psychiatrist and then if still having problems go see a different neuro. If you don't have confidence in your doctor then you need to find one you do. I had to see 3 neuros over 5 years before I got my answers. I wish you peace. Good luck

 

[SadsackinCali]

Thanks for the response vickim. His information didn't sound right to me. I am going to see the psychiatrist, but I also changed Dr. today. So, I guess I'm gonna be starting this process all over from the beginning. It's taken me 5 months to get this far, I guess it will probably take another 5 months to move forward in this process again. It's FRUSTRATING! I'm thankful I have such a supportive family who has helped me stay strong through all of this. That's been my saving grace.

Allison

 

[Nighthawk]

EMG can and should detect pinched nerves but, that is not the only thing an EMG can do.

It can help Neurologists to make a right diagnosis of some neurological disease affecting your nerves and muscles.

It can also reveal if there is denervation and/or re-innervation occurring in your nerves as well as some kind of neuropathy.

It's a very useful diagnostic tool to Neurologists because a CT-scan or an MRI alone cannot reveal what is really going on with your nerves. It can also avoid a misdiagnosis.

HTH

 

[wader1970]

If a person is getting fasiculations and they do an EMG, how does it come out clean?

 

[vickim]

An electromyogram (EMG) measures the electrical activity of muscles at rest and during contraction. Nerve conduction studies measure how well and how fast the nerves can send electrical signals.

Nerves control the muscles in the body with electrical signals called impulses. These impulses make the muscles react in specific ways. Nerve and muscle problems cause the muscles to react in abnormal ways.

If you have leg pain or numbness, you may have these tests to find out how much your nerves are being affected. These tests check how well your spinal cord, nerve roots, and nerves and muscles that control your legs are working.

Why It Is Done

An EMG is done to:
Find diseases that damage muscle tissue, nerves, or the junctions between nerve and muscle. These problems may include a herniated disc, amyotrophic lateral sclerosis (ALS), or myasthenia gravis (MG).
Find the cause of weakness, paralysis, or muscle twitching. Problems in a muscle, the nerves supplying a muscle, the spinal cord, or the area of the brain that controls a muscle can cause these symptoms. The EMG does not show brain or spinal cord diseases.

A nerve conduction study is done to:
Find damage to the peripheral nervous system, which includes all the nerves that lead away from the brain and spinal cord and the smaller nerves that branch out from those nerves. This test is often used to help find nerve problems such as carpal tunnel syndrome or Guillain-Barré syndrome

 

[Nighthawk]

I have never understood what a "clean" EMG or a "dirty" EMG mean.

Both terms ("clean", "dirty") are used very, very frequently in this sub-forum but I have never understood either one.

I better understand when EMG is referred in terms of acute or chronic "denervation" and/or "re-innervation" because I do know what these two are doing to the nerves.

However, I do imagine that when there is BFS showing up on an EMG, that means that no denervation is occurring to the nerves contrary to ALS.


Regards,

 

[vickim]

Normal results (clean)

Muscle tissue at rest is normally electrically inactive. After the electrical activity caused by the irritation of needle insertion subsides, the electromyograph should detect no abnormal spontaneous activity (i.e., a muscle at rest should be electrically silent, with the exception of the area of the neuromuscular junction, which is, under normal circumstances, very spontaneously active). When the muscle is voluntarily contracted, action potentials begin to appear. As the strength of the muscle contraction is increased, more and more muscle fibers produce action potentials. When the muscle is fully contracted, there should appear a disorderly group of action potentials of varying rates and amplitudes (a complete recruitment and interference pattern).

Abnormal results (dirty)

EMG is used to diagnose diseases that generally may be classified into one of the following categories: neuropathies, neuromuscular junction diseases and myopathies.

Neuropathic disease has the following defining EMG characteristics:
An action potential amplitude that is twice normal due to the increased number of fibres per motor unit because of reinnervation of denervated fibres
An increase in duration of the action potential
A decrease in the number of motor units in the muscle (as found using motor unit number estimation techniques)

Myopathic disease has these defining EMG characteristics:
A decrease in duration of the action potential
A reduction in the area to amplitude ratio of the action potential
A decrease in the number of motor units in the muscle (in extremely severe cases only)

Because of the individuality of each patient and disease, some of these characteristics may not appear in every case.

 

[wader1970]

I am getting fasiculations all over my body and especially in left arm and left leg. When they did the EMG it came out normal. This seems odd to me but as I cant understand why it didnt setect anything?