Can someone PLEASE explain to me LMN Verse UMN Weakness?

[shizzy]

What is the difference? I keep hearing UMN weakness will cause spastisity, stiffness, ect

I 've read many pals say their 1st symptom was arm weakness, hand weakness, finger weakness, ect. but how does it feel? Weak, meaning tired? IE: holding a cup gets heavy?
Weak, meaning cant move it? Do you make an effort to move it, but it just doesnt respond, IE: moving an ear?


I cant understand this.

Respectfully,

 

[rose]

Shizzy,

My brother can wiggle his ears

I don't have much UMN, so not a good person to differentiate them for you. My weakness (LMN) started with my voice, and it was just a gradual decline in volume as well as quality. I lost a range of pitch early on. The weakness moved to my pharynx and soft palate, and again, it was gradual, just became harder and harder to do what I took for granted before.

I believe that if a person was weak due to UMN, that it would be a long time coming on, as it would be weakness due to disuse. AND that person would have other clinical signs of UMN involvement, abnormal reflex responses, etc.

Its good to understand what is being experienced, so it can be explained to the doctor. Many people use fatigue interchangeably with weakness, but it is not the same thing.

I don't think you can get an absolute answer as to how weakness first manifests itself, because people experience it at different progression rates. Its a safe bet that it did not happen for anyone overnight, or over a period of days or even weeks. If the weakness happened over a period of weeks, and it was a form of ALS, the other clinical signs would be so clear that a diagnosis would be made quickly.

That said, there are many other causes of weakness. It does not have to be motor neuron driven...

 

[Tokahfang]

To contrast that illustration, I have UMN weakness in my voice developing. My voice starts out pretty normal still, but quickly declines with use, and faster if I don't relax between sentences. Singing is getting impossible and reading aloud uses it up very fast, because it is hard to take breaks. If I talk at a measured pace, pausing whenever it gets stiff, I can seem normal to strangers.

 

[halfin]

It is hard to describe what weakness feels like. It is not really that things feel heavier, exactly. There are things I can't lift anymore, and things I can barely lift, but they don't feel heavier because if they were heavier I would feel that pressure in my fingers and hands. It's not like lifting a 10 lb object feels like it used to lifting something 30 pounds, because all the other sensations aren't there that you'd have with a genuinely heavy object.

The best I can describe it is that most people have felt weak from time to time due to sickness, or perhaps overuse of a muscle. You've been sick in bed for a few days and when you finally get better and stand up and walk around, you're weak and shaky and unsteady. My legs feel like that all the time. Or maybe you were at the gym and worked your biceps muscle to exhaustion using a dumbbell, now that muscle is weak and if you tried to lift even a small weight you would have trouble. Of course you quickly recover but during that time, that is similar to how my arms feel.

As far as UMN vs LMN, UMN problems as you say tend to produce problems with movement like spasticity and stiffness. For me it is most noticeable in my right hand - if I make a fist and then try to open my hand quickly, my fingers move very jerkily and in steps, and it takes several seconds to open all the way. They say UMN problems can produce weakness, but I can't tell them apart as I have both UMN and LMN effects. So I can't tell whether UMN weakness might be different. They do say that UMN weakness tends to be less severe, while LMN weakness progresses to total paralysis.

 

[HalsWifeFran]

UMN is a problem with control - timing of muscle contraction and relaxation. You initiate a specific movement but your hand/arm/leg/tongue does something else - it moves too fast or too slowly or jerks. It can seem like weakness because when you try to walk, for example, if your legs and feet aren't coordinated, you can fall or collapse. Although affected muscles do atrophy with UMN involvement, the loss of muscle size is more gradual, because the muscles are still being asked to contract - it's just that they aren't doing it in a very functional or useful way.

LMN is direct weakness/fatigue. No rapid, jerky, uncoordinated or stiff movements. The muscles stop receiving signals to contract. So they stop working. You try to move a certain way, or do something, and you can't because you're not strong enough.

Most PALS have a combination of UMN and LMN involvement. But some, like Hal, show more UMN, and other show more LMN. And it can change.

I have to say, as someone watching from the outside, powerless to stop the process, I think UMN and LMN involvement are both pretty awful.

 

[peter57]

Welcome to the forum Fran.

Both you and Hal gave a very good description of the difference between UMN and LMN.

So did Rose and Tokahfang re their symptoms etc


cheers
Peter

 

[abbas child]

I'm very glad to be getting this information. Shizzy, thanks for asking. I'm finding out how much I've misunderstood. I'm predominately LMN, but have begun to notice some UMN, which I'd not have realized but for this forum.

Hello Fran, I'm so glad you've come into the conversation.
Ann

 

[shizzy]

You've all been so helpful, As always, kind & considerate!
Thank you for helping me to understand!

Respectfully,