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Senior member
Apr 27, 2007
How is the NVC test used to diagnose als? Is it used to differentiate from other disorders, or to define the diagnosis of als? I am not clear on the value of this test. It seems that the emg is the more critical test since it looks at nerve damage, but the NVC is used to point to other disorders, if the emg is normal. Is this correct? I know that on one site it states that the NVC is normal in ALS, but possibly abnormal in neuropathy. Yet, on that same site it also states that NVC can also be normal even with neuropathy.
Is the NVC always normal in ALS?
Jamie will be able to give you the best answers to your questions. Hopefully he will see your post and jump in! My NCV test was used to rule out Isaac's, but is also used for als. I just am unsure as to the way it is used for this. Good luck! Leslie
vmd -

These sound like good questions for you to ask your physician.

Liz - most of us who are undiagnosed have asked a trillion questions and it is very difficult to ask a physician all of them, especially if you think of them after you have left your appt. That's why we come to this forum and ask questions. Also, it is the experience of us undiagnosed members that the physicians cut and dry answers don't always work. So, that's why we're here to help each other on the "Do I have ALS" site! Leslie
My neuro only conducted the emg and not the NVC, that is why I ask. I may call him back and find out why, however.
VMD, Liz and LTR are right on...

What you need to do to cover both of those basis, is to WRITE YOUR QUESTIONS DOWN!

I do that exacth thing when i don't write them down...i forget 90% of what i wanted to show and ask, becuause i get so nervous and all goes to crap. I even wrote all my questions down last time and didn't ask 1/2 of them.

OK, on the NCV. Yes, i've educated myself on this too.....

The story line is....NCV's are normal in the majority of ALS patients, however, that doesn't mean there are defects int hem in ALS patients. ALS is a nerve disease, so, the possiblity for NCV issues are there.

MY last NCV showed "F Wave" afterdischarges.....? the neuro told me my muscles were very very irritated....naturally....i told the man...."what, do you think i'm here for fun"....LOL

ALS is more charactarized by, EMG - Fibs & PSW's and also Axon loss and weakness and / or atrophy signs, coupled with upper and lower motor neuron signs. Which, i have no clue off the top of my head which each entails, but, if you got weakness, twitches, hyperactive reflexes and atrophy and / or clonus, you would have both upper and lower motor neuron which is the charasteric of ALS.

Take care.


Thanks for the link Al.

If I read the info correctly, the NVC is used to detect a nerve probem and the emg a muscle problem. Apparently, the NVC is used to identify other conditions, besides als, which may be causing the symptoms. In other words, the nvc is not vital to the diagnosis of als, but it is used to find alternative diagnoses. Perhaps, my logic is wrong, however.

This quote from the wikipedia (Yes, I know this is not necessarily a trustworthy site), explains it this way:

"Because symptoms of ALS can be similar to those of a wide variety of other, more treatable diseases or disorders, appropriate tests must be conducted to exclude the possibility of other conditions. One of these tests is electromyography (EMG), a special recording technique that detects electrical activity in muscles. Certain EMG findings can support the diagnosis of ALS. Another common test measures nerve conduction velocity (NCV). Specific abnormalities in the NCV results may suggest, for example, that the patient has a form of peripheral neuropathy (damage to peripheral nerves) or myopathy (muscle disease) rather than ALS."

So it seems the EMG is used to support the diagnosis of ALS, while NVC is used to posit other conditions besides ALS.

Either way, my neuro did not conduct an NVC.
Same here annmarie...i' feel rushed..and are usually a wreck.

I might get some relaxant's next time i go in there
I am going to weigh in with another reason for doing your research. Two of my doctors have told me they appreciate the fact that I am informed. It makes me a partner in my care, I suppose. Plus I am a person who sometimes needs things presented in a couple of ways before it "clicks" in my brain. I get the layperson's explanation, the medical explanation, and I do some reading on the side. That's how I prepare for a visit to the clinic. It takes about as much preparation as preparing for a big meeting at work but it is way more important. After all, this is my health. Cindy
The neuro said the emg was completely normal. Of course, he also said that I may eventually be diagnosed with ALS, but he did not see evidence of it now based on his clinical and emg exams. So for me, like many of you, it's waiting for the next exam. My symptoms, after all, are still there. I seem to have reached a plateau with respect to my weakness on my right side when I lift weights. In fact, I have increased my ability to lift weight when I bench press on my right side. It is not to the level it was before I noticed weakness, but it has come back to almost that level. For example, I use a machine that allows me to bench press weight with either arm. About 2 months ago, I noticed I could no longer lift 80 lbs. ten times with my right arm (something I could do before easily). Then, I was not able to lift 80 pounds more than 4 or 5 times. I gave up that exercise. This week, I went back to the same exercise and I was able to lift the 80 lbs. ten times again with my right arm. However, the right side weakness is still there because if I fatigue that arm, then I can't do the same number of repetitions with my right arm as I can with my left arm. Sorry about the explanation, but I keep fairly accurate track of the strength changes I have noticed.
With the doctor thing, do you all ever feel like you've asked enough questions and you either don't want to irritate the doc with another one or he will think you're a quack for too many? Even with my list of questions, once I get there I ask a few of the most important and get a little inhibited to ask the rest. Those are usually the ones you guys answer!

Cindy - I am exactly the same way. Sometimes a doc will explain why something doesn't need to be tested or why something is negative without giving the reasons for his answers. I usually get it after I have a few explanations. It would be so much easier if the docs thought like us!

While we are on the subject, does it matter if the NCV is done on a limb that hasn't bothered me? My right side tends to give me more problems than the left and legs more than arms. The NCV was done on my left arm. Thanks. Leslie
I, for one, am like you in that I have a big list of questions for the doctor and somehow I get sidetracked and don't ask all of them - even with them written down. Or, their answer to one question, makes me think of a different question, and off we go on that topic. And, you're right - sometimes I think I've asked my number of questions.
I guess we all put doctors on a pedestal ( or maybe not?), but they put their pants on one leg at a time just like everyone else. Some are just a bit more approachable and willing to talk. But, this is our health, or our loved ones, so we need to be a good advocate - so what if the doctor gets annoyed.
I agree that, as patients, we need to become familiar with our situation and advocate for ourselves. The reality is that doctors see many patients during the course of the day, and it can become a routine for them. In addition, we know that doctors are capable of making gross errors in their practices. For the most part, however, they are very professional.


For now, I will sit and wait. I am not certain why my right arm managed to gain some strength, although that arm still fatigues quickly. It's quite obvious to me that something is wrong and I'm still pessimistic. However, I also believe God can heal me if He chooses to do so. I pray for such an outcome.

By the way, you had asked about the number of insertion sites during the procedure. I know he did 3 limbs and a total of about 12-14 punctures. Take care.
ltr said:
Liz - most of us who are undiagnosed have asked a trillion questions and it is very difficult to ask a physician all of them, especially if you think of them after you have left your appt. That's why we come to this forum and ask questions. Also, it is the experience of us undiagnosed members that the physicians cut and dry answers don't always work. So, that's why we're here to help each other on the "Do I have ALS" site! Leslie

OOOOOOOOOOPS! I accidentally responded on a thread in a category to which I no longer belong.

vmd - please excuse my intrusion.

Leslie - thank you for pointing out my error.

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