new EMG?

[fredrik]

Hello again,

I've read a lot here and other sites about EMG.
Is this correct?
If you do EMG before atrophy/musclewaste or/and weakness, there is a possibility to get a negative EMG even though you have ALS, because it's too early?
If you do EMG after someone other then yourself can notice musclewaste or/and you can feel some weakness (even though it's not clinical weakness) or/and fasics/twitches etc and it's done in right muscles by expirienced neuro etc, and it's negative, then there is no reason to still worry about ALS?

By the way, howcome Mr.Wright know so much about ALS? is he a neuro? i understand he don't have ALS?
Anyone know how many members there is on this site?

Fredrik

 

[ptich]

If you have LMN symptoms, negative EMG is more meaningful than if you have UMN symptoms only.

It is all probabalistic, of course.

Apparently certain types of fasciculations are UMN symptoms, so weakness / atrophy is probably a more reliable indicator of LMN involvement.

As Blizna posted earlier, fasculations alone with no weakness and with negative EMG is very unlikely to be caused by ALS.

 

[perplexed]

good questions

Hi Fredrik,
These are good questions and my feeling is that only a neurologist (or preferably two or three, for second and third opinions from neuro diagnostic centers at major teaching hospitals are equipped with informed answers).

I had the same contradictions from various responses on this site; one thread said that the EMG can pick up problems before the patient themself feels symptoms. Another said that you can have ALS for a while before an EMG detects muscle weakness. One said that if the patient has upper motor neuron symptoms and lower neuron findings on the EMG, that doesn't necessarily mean ALS. Another said that lower motor neuron trouble is picked up by the EMG but not how conclusive this is for a diagnosed.

I confess I haven't had the courage yet to pursue my own findings - my husband is in the middle of being tested and I am walking the line between wanting to be informed and making myself crazy.

I hope this is of some help but am afraid I've only confused matters further.
All the best,
Muffy
(perplexed, Montreal)

 

[wright]

A few things that need to be cleared-up:

No, your EMG will not be clean if you have ALS. If you have ALS, you have both upper motor neuron death and lower motor neuron death. You will have clinical signs of upper motor neuron death and you will have a dirty EMG indicating the lower motor neuron death. You will also not get a definitive ALS diagnosis unless the El Eshorial criteria are met.

If you have lower motor neuron symptoms (muscle weakness, fasciculations, atrophy) and they were due to ALS, the EMG would pick it up by showing active denervation (positive sharp waves and fibrillations and fasciulations) along with reinnervation (large and/or elongated and/or polyphasic motor unit amplitudes).

Upper motor neuron death (PLS for example) can certainly be the only pathological condition initially, which is what happens with PLS for example. This is diagnosed clinically. The EMG would be clean, because the upper motor neurons do not innervate the skeletal muscles. Certainly at a later time, the upper motor neuron death can be accompanied by lower motor neuron death (this would be diagnosed with an EMG) and then a definitive diagnosis of ALS would be given . . . IF . . . the El Eschorial criteria are met.

Upper motor neuron dysfunction/death does not cause muscle fasciculations. Upper motor neurons do not innervate skeletal muscles, so there is no way for them to cause motor units to be excited, which is what fasciculation are . . . electrical activity of individual motor units.

EMG's can only detect lower motor neuron problems because those neurons innervate the muscles. Therefore, if someone has solely upper motor neuron involvement, then the EMG will be clean. Involvement of upper motor neurons is determined clinically.

The EMG is incredibly sensitive and can detect abnormalities before the neuro or the patient is aware of it. Many times people who have ALS will get an EMG in the affected limbs where EMG abnormalities will be found . . . then . . . in CLINICALLY unaffected limbs, those same EMG abnormamlities will be found but not quite as serious yet.

The reason a dirty EMG doesn't always mean you have ALS, is because you can have a dirty EMG for a gazillion different reasons (pinched nerve, slipped disc, carpal tunnel, CIDP, etc., etc.). If a dirty EMG was always indicative of ALS, then ALS would be pretty darn easy to diagnose. Once again, if the El Eschorial criteria are not met, you will not have a definitive diagnosis of ALS.

 

[suzannj]

May I chime in and say this was, by far, THE BEST, most concise, well-written, understandable reply / explanation of EMG interrpretation and application for ALS diagnosis that I have EVER read!

I wish we could somehow cut and paste Wright's post on the top of this part of the Forums, or have it come up first in a search when people type in "EMG". Everyone should read this!

VERY HELPFUL Wright, awesome job

 

[olly]

ok!

i began with umn symptoms/pls,i started getting twitching or became aware of it at least 6mths after the symptoms started.
many with pls state they have twitching as a symptom.

are we talking about two different things with regards to fassic,s and twitching?
many medical sites and neuro,s class them as the same thing.
so it must be the severity,speed ,rythem that determines benign fassic,s?
so a twitch or indentating in muscles is not the same as continuous wriggling?
some with bfs fassics can seem severe yet some with als have said they dont get that much.

sorry wright,i am thinking out loud what may confuse so many people.:wink:
NO WEAKNESS,NO ATROPHY,CLEAN EMG=NO ALS.

small print
(i will not be responsible for any disputes regarding anything mentioned above)

 

[Al]

I copied and pasted wright's emg primer and it is a new sticky EMG 101.

AL.

 

[wright]

Caroline (olly)

Twitches and fasciculations are the same thing. Some neuro's will call ALS twitches "fasciculations" but it's mere semantics. Twitches / fasciculations are due to stimulation of motor units (that is what the EMG measures: electrical activity produced by muscle cells of motor units), which in turn causes the muscle cells of the motor units to contract.

As I said in my earlier post, the lower motor neurons directly innervate the muscle cells, so the dysfunction and death of the lower motor neurons will direclty cause the fasics. Initially it was thought it was mainly due to reinnervation but now it is also thought that denervation of the muscle cells could also play a role.

When it comes to non-denervating fasics, they still don't know exactly why they happen, although nerve irritation is a leading theory. The cramping and spasticity of PLS cause muscles to contract violently and become rigid, which can certainly cause the affected muscles to irritate nerves . . . but . . . it wouldn't be due to direct dysfunction / death of the upper motor neurons (it would be an indirect consequence). Therefore, I can see how people with PLS could (doesn't necessarily mean they would) have fasics due to their symptoms.

One of the points in my earlier post was to dispell something that was said about upper motor neurons and how it was stated/implied that their dysfunction directly cause fasics. That is simply false.

 

[hopingforcure]

Caroline you are correct, PLS can definitely cause twitching of muscles. The problem here is only a few of us crazy research fools.(LOL), like Wright and you, and Cindy and Al, and Jimmercat, and a bunch of others who I am forgetting, Oh yah Crystal, Rose, Beth, Brenda, Zen, .................................and any other crazy researchers. Sharonca forgot you.. Can make heads or tails out of the entire UMN LMN thing, sometimes I feel like you guys are the only ones in the world who it makes sense with. I am not patting myself on the back in any way, it is just that this stuff is so entailed and technical that most doctors, and I do not even half understand it. I know we try to explain it but most people just get kind of glazed over from it all. I know that my family doctor just looks at me like I am from MARS when I try to explain the whole neuro-muscular thing to him. The other day I was at the eye doctor, and he actually got it.
My that was great, we talked and talked.... I got you Wright, you are saying that pls twitching is basically benign. While LMN twitching Malignant... Very true.
Here is something that can really muddy the water, I was talking to a PHD and he felt that UMN problems could cause a small amount of atrophy, and guess what I believe Caroline has also read that... SO again the more we think we know, the more we do not. I do want to let everyone know that I am so grateful to have a place to share and exchange ideas.. I wish we could all meet personally and pow wow.. We would probably find a cure.. Wright could then lead our medical team of patients to victory..................

 

[suzannj]

Al: You're awesome! I really hope that the newer folks who come on the site seeking answers take the time to read the sticky's! Can't hurt to try . . .

Thanks again for being such a good "listener"
Suzann

 

[olly]

wright
thankyou for your explanation,i did know i was just firing out thoughts others may have.
still it was good to hear you explain it in your highly intellegent but simple putting way.
when i was first being tested for suspected ms i thought the twitching was because of this.
i know twitching from iritated nerves can be a symptom in ms.

hoping
i think wright has explained before atrophy in pls would be from disuse.
now this used to puzzle me,i thought how can you have disuse atrophy in a limb you can still move:roll:
i think i am correct in saying as pls progresses and muscles weaken they can develop disuse atrophy from limited use.
please correct me if i am wrong wright.

i am not sure but i think with my atrophy in my foot/ankle is caused by the hypotonia/loss of contraction in that leg.
i found out the hypotonia is the cause of the collapsed arch.
i did have the constant wriggling fassics in that foot long before the atrophy.

thankyou to both of you:grin: