MMN v ALS

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HollyridgeLife

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Distinguishing MMN from ALS

My former wife is awaiting a diagnosis of either MMN or ALS. Her symptoms have developed fairly rapidly, from what we can observe and what she reports. She has received one round of infusions for MMN and indicates no change thus far. We’re wondering how rapidly MMN progresses. From onset to the presentation of symptoms – fatigue, muscle weakness, difficulty in walking without support, like hiking or walking sticks – how much time elapses, in most cases? Are these symptoms consistent with both MMN and ALS?
 
This article gives a good overview of MMN vs. ALS. In addition, MR neurography is an imaging study that can help differentiate the two. Since the hands are usually what is most affected in MMN, not knowing what her EMG and exam showed (feel free to post either, blacking out personal information), I do have to say that MMN seems less likely than if you had spoken of upper extremity weakness. MMN progresses more slowly and is seldom fatal except for treatment effects like blood clots because there is no impact on breathing or eating.
 
How rapidly do ALS symptoms typically manifest and then progress? While awaiting a formal diagnosis, the individual in question – a woman in her late’ 60s – can no longer walk without support (walking sticks, in this case) and has very limited use of her left leg. The situation has worsened within the last four to six weeks (despite an IVIg infusion for suspected MMN). What kinds of conclusions can we draw, if any?
 
After one round of IVIg infusions for MMN – which resulted in no change in the person’s condition – a second round is schedule before the end of the month. Typically, how long does it take for MMN to work – that is, to show real-world improvements in mobility?
 
Hello-

I've moved your posts to your already open thread. It helps people to keep things in one place so they can see what has already been discussed. If you would like to add questions, please keep posting in this thread.

I am sure someone more knowledgeable than me will weigh in with some answers for you shortly.

~F
 
Q1 - there is no real answer, some PALS are gone within months of diagnosis, and others live for many years. I wish we could give something more solid or typical.

Q2 - Usually some change is noticed within weeks, but can take longer.
The main thing for now is to make sure she avoids falls by using mobility aids, and make a list of questions like this to ask the doctor next week at the next infusion.
 
I was in MMN vs. ALS limbo for some time. There are some indicators that can distinguish between MMN, which is an autoimmune disease, and ALS, which is a neuronopathy. First, I'm assuming your ex-wife has no upper neuron symptoms such as spasticity or hyper reflexes, because upper neuron issues would rule out MMN. If she is already getting IVIG infusions, then I'm sure she is only exhibiting lower neuron symptoms.

The article that lgelb mentions above is very helpful for understanding characteristics of MMN, but in case you don't feel like wading through an academic/scientific article, I will boil it down for you - The strongest indicator of MMN is if the doctors find "conduction block" when they do the Nerve Conduction Study (NCS). This study is usually done in conjunction with the EMG. If there is no conduction block, that's not necessarily the end of the story. You would have to look at other things, such as whether she has elevated levels of anti-GM antibodies in her blood, which would weigh heavily toward MMN. On the other hand, if there are elevated levels of creatine kinase, that weighs more toward ALS. Finally, MMN develops more slowly than ALS, so her quick progression would weigh against MMN. There can be other factors too.

I wouldn't make any conclusions about the lack of improvement after one round of infusions - it usually takes longer than that.
 
Again, problems walking without arm/hand problems suggests ALS (as opposed to MMN) more strongly than most of these criteria. As Eric says, the fast progression does as well.

But there are other motor neuropathies and neuronopathies. So her being at a major academic center for neuromuscular disease is important.
 
When I was first diagnosed, the neurologist told me it was either MMN or ALS. He sent me for three ivig infusions while waiting for my second opinion appointment with the ALS specialist. Three months later, I was officially diagnosed with ALS and was told by the specialist that if I had a positive Hoffman test, which I did, that would have ruled out MMN. The first neurologist apologized and had the infusion bill reversed as it is quite expensive. I've never researched this, so I'm not 100% sure. Good luck to you!
Marty
 
I think 3 rounds is fairly usual for an ivig trial unless something happens in the interim to make the clinical picture clear.
 
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