Question about EMG

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Question about EMG

Postby thescream on October 1st, 2002, 1:24 pm

I had an EMG on my left leg and left arm that came back negative about 3 weeks ago after suffering fasciculations all over my body but mostly in those two limbs.

Now my fasciculations have moved more to my right leg and I am experiencing what I believe to be weakness. Would an EMG pick up ALS in just the spots it was tested or would it show some signs of ALS in other limbs.

Also, does fasciculation in a limb mean that ALS is starting to damage that particular area or it just means you might have ALS and it is damaging somewhere else.

I'm wondering if I should get another EMG
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Postby Twitcher on October 1st, 2002, 3:30 pm

Ah, we've all been there. It took me two EMGs and numerous visits with several different Neurologists before I accepted the fact that I was fine. I too had "weakness" in my leg. My knee felt rubbery and my legs would shake when I would walk down stairs and ache on the way back up. It would last for weeks on end. Then I would go see a Neurologist again and it would be fine for awhile. Then, something else would start freaking me out. It was an awful, vicious cycle.

In ALS, once twitching starts there is ALWAYS damage that an EMG will pickup. I pulled the following from another post on in this forum. This should put your mind at ease!

Jeff wrote:Here is some info I have gathered that I compiled into a "help document" for time of stress, anxiety, etc. These are all facts from neurologists I have seen or from neuro's on medhelp or textbooks, no hearsay or bboard posts from users:

What we learned in neurology was that fasciculations in relaxed muscle are NEVER indicative of moter system disease unless there is an asociated weakness, atrophy, or reflex change.

Since fascics alone are not indicative of muscle disease there is no greater chance of coming down with ALS as in the general population, which is really quite low. We have seen these benign fasciculations last months and for years. No one really knows the etiology.

Just 10% of cases present with LMN (weakness, muscle wasting, and fasciculation) signs alone (UMN - weakness, spasticity, hyperreflexia, and Babinski's sign).

Consultation in Neurology, Caplan/Kelly 1991
Generalized fasciculations. The presence of generalized fasciculations, often accompanied by cramps, always raises the specter of Amytrophic Lateral Sclerosis(ALS) and arouses considerable anxiety in the patient and in the physician. However, if the patient has a normal electromyogram or no weakness when followed for 6 months, serious disease can be excluded and the diagnosis of benign fasciculation syndrome given. Patients with ALS more commonly have focal fasciculations and cramping in concert with progressive weakness. The electromyagram at this stage is always abnormal, showing more widespread evidence of lower motor neuron dysfunction.

Consultation in Neurology, Vol.II Caplan/Kelly
Fasciculations are sudden unpredictable, visible twitches of small parts of muscles. Generally, these ripple the surface of the skin but are not sufficient to move joints, except in the hands, where they may jiggle the fingers. They can be generalized or focal.
General Fasciculations are discussed in detail in Part VI Weakness and neuromuscular symptoms. However, if they are present for atleast 6 months with no signs of neuromuscular disease, or if the electromyagram is normal(except for fasciculations) then they are considered benign fasciculations. Fasciculations are common in the calves, are associated with cramps, and frequently accompany anxiety or fatigue or stress states.

Fasciculations that have been present for several months and are unassociated with other evidence of denervation determined clinically and electromyographically may be considered benign. Although the mechanisms are not fully understood, Benign Fasciculations are quite common but not often recognized.

Textbook of Clinical Neurology, Goetz/Pappert 1999
Fasciculations are a feature of disorders of the anterior horn cell or root compression. Therefore fasciculations are often viewed as an ominous sign. They need not be because they are commonly experienced as a benign phenomenon in the absence of any disorder of the motor neuron or spinal nerve roots. Fasciculations of a benign nature can generally be distinguisshed from fasciculation secondary to lower motor neuron disease by several features. They have a predilation for males and for certain muscle groups, especially in the calves and thighs. When they occur in the arm muscles they they tend to be seen as repetitive twitches in the same muscle fascicle as opposed to random non stereotyped twitches of many parts of the muscle seen in patients with anterior horn cell disease. Benign fasciculations in the calves are more difficult to distinguish clinically because they may be frequent or multiple and have a malignant appearance. However, there is no associated weakness or atrophy of the affected muscle with benign fasciculations.

1989 edition of Adams and Victor's Principles of Neurology – “It is most unusual for the fasciculations to antedate the weakness, a simple clinical rule is that fasciculations in relaxed muscle are never indicative of motor system disease unless there is an associated weakness, atrophy or reflex change. Eventual recovery can be expected."

Fasciculations caused by ALS are due to dying muscle tissue (actually necrotic). So, fasciculations due to ALS are always accompanied by muscle weakness and EMG changes. Benign fasciculation are not due to dying muscle tissue, but irritated muscle membranes. They are not accompanied by muscle weakness, nor are there EMG changes. Since muscle is not dying in benign fasciculations, they tend to be spread out and in a variety of muscle groups. In the early part of ALS they tend to be in specific muscles, more distinct, because the muscle is dying. The literature indicates that benign fasciculations are usually more spread between muscle groups and can worsen with anxiety and fatigue. They can reoccur in the same muscle groups and also be variable.

In ALS, the nerves located in small fiber of a muscle begin to lose their connection. As such, they begin a process of slight fasciculation, which is like a distress signal for another nerve to come to it's rescue and reinervate. ALS twitching starts out very fine, and pretty much invisible to the naked eye. However, since these affected muscle fibers are no longer working well, you tend to notice weakness and possibly slight atrophy before you ever notice twitching. The comment about ALS twitching not coming and going is very true. Once this muscle gets cut off, unless it reinervates, it continues to rhythmically (important, meaning steady and constant) send out these distress signals harder and harder and more frequently. It doesn't stop until complete muscle death, which, by then, you won't need twitches to tell you something is horribly wrong. This is important, because the nerves around it have also begun to lose their connection and are beginning to fasciculate (thus, no new nerve supply can come to the rescue). That means progression of twitching--from a very small localized area with very fine,steady fascics that you cannot even feel or see to a larger group with more intense twitching.
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Postby Debbs on October 1st, 2002, 10:02 pm

I havent had an EMG yet could anyone explain in brief what I should expect ? and I was wondering if they test for clonus ? and if clonus is revealed does that mean you have Als???

Thanks Deb
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