Yeah, I don't think I'd wanna be a neuro. Your comment (the gray area bit not the cranky part) reminds me of something the neuro who did the exam for the clinical trial said. He said I was complicated and when I asked what he meant by that he said I was the kind of patient that drove doctors crazy because they could tell something was wrong, but they can't figure out why. That didn't make a whole lot of sense to me in that context since I'm already dx'd and he was just supposed to be coming up with an EDSS (Expanded Disability Status Scale) score, but I do wonder if neuros have that experience a lot.
sho
I think you're right. The NCS is pretty good, but it doesn't pick up small fiber neuropathy and can miss other causes. There's a whole lot of gray areas in neurology. Maybe that's what makes the neuros so cranky and unwilling to be questioned. Ya think?
Quix
I have a question about NCS/EMG. My understanding was that a normal result is like a lot of these MS tests--it makes it less likely you have peripheral neuropathy, but it doesn't rule it out completely. In particular, the NCS won't pick up small fiber neuropathy.
In my case, neuro #1 dx'd me with peripheral neuropathy when I had a normal NCS so he seemed to think it possible, at least early on. Neuro #2 somehow got a positive result for mild sensory neuropathy (he tried really hard, but I can only think it was some kind of anomaly). Despite this, neuro #3 told me before he sent me for yet another nerve conduction study that he thought the results would be normal (they were). So sometimes it doesn't seem to me like these neuros know what they're doing.
Anyway, it just seemed to me that from what I read/understood, the NCS wasn't absolutely definitive that there's no peripheral problem.
sho
So does this mean that the pain/stiff neck and the transient numbness/tingling in my arms at least is coming from the brain damage and that I don't have any Peripheral damage in this area?
~Santana~
Think of the EMG/NCS tests as being like the testing that the phone company does when your service goes down. They check the houshold wiring and if that checks out they know that it is a problem in the more central switching stations.
EMG/NCS should be negative in MS (or in Santana's case possibly, ADEM). If they are positive, it doesn't rule out MS, but makes everything harder to tease out. You can have causes of peripheral neuropathy and also have MS. Examples:
Diabetic neuropathy and MS
Back or neck disc/pressure problems and MS
Carpal Tunnel Syndrome and MS
Q
Here is a little blurb I wrote up on EMG. It sounds like the neuro who spoke to you was giving you the straight dope! You clearly also had Nerve Consuction Studies.
The EMG (Electro-Myo-Gram) is a test that measures the function and health of the muscle itself and, to some extent, the health of the nerve signal ARRIVING at the muscle. The EMG stimulates the muscle directly to see check a couple of things. The test is done by inserting a fine needle (which is wired to a recording device) into the belly of the muscle and recording the electrical activity of the muscle first at rest (as the needle is inserted) and then when the patient uses (contracts) the muscle smoothly. The electrical activity is recorded on paper or by a computer and also there is often a sound generated which may be recorded along with the measurement and which also gives auditory information.
1) A resting muscle is electrically quiet. There is a short burst of electrical activity from the irritation of the needle insertion. The needle is left to record the muscle at rest. The normal muscle should then become quiet. If there is spontaneous electrical activity when the muscle is at rest, this can indicate either muscle damage or disease or an abnormal nerve impulse arriving at the muscle.
2) The patient then begins to contract the muscle smoothly. The needle electrode measures what is called the "Action Potential" of the muscle. Initially just a few of the muslce fibers contract and their potential are measured. As the muscle contracts more and more fully, more muslce fibers join in and the EMG records more and more wave forms. The wave form of the electrical activity is examined for it's height (amplitude), it's shape, and it's duration.
3) Muscle disease is indicated by a short duration of the action potential and by abnormalities in calculated ratios between the various measurments.
In doing an EMG of a muscle, the needle is inserted deeply, analyzed, then pulled back a few miilimeters, analyzed again and such until the needlele is out of the muscle. It is then reinserted in other parts of the same muscle until enough data is collected.
4) EMGs can give indirect information on neurologic problems, that is problems with the nerve signal that is stimulating the muscle to contract. These findings might include a markedly prolonged action potential Also, there may be a greater amplitude in the action potential.
This procedure may be painful for some people and less so for others. The muscles tested may be sore for days after the test.
I haven't written up the one on the NCS. But since they were both normal it does indicate that you have a "central" cause for your problems. Yes, that would rule out GBS and Miller-Fisher Syn. Normal EMG and NCS (NVS) point to a central cause for nerve pain and paresthesias. Those tests are done to look for peripheral disorders that can mimic MS.
Quix