SCI Awareness – Upper Motor Neuron vs. Lower Motor Neuron Injuries

Once you have a SCI, it is easy to know that your lungs, or arms and legs are weaker. But there is much more going on in your body that you must learn. The brain stops at the top of your neck and your spinal cord is the pathway for every single message that is sent out.

Like we discussed yesterday, if you are a complete injury, none of those signals are going to get past the level of your injury. If you are an incomplete, something will get through.

Stick with me…this does make sense by the end!!

Our spinal cord has upper motor neurons and lower motor neurons. One of those will have gotten damaged. Higher injuries affect the upper motor neurons. And the L-level lower injuries affect the lower motor neurons.

What happens, is that a signal tries to go from my brain to my body. It hits the damaged part in my spinal cord and the messages are scrambled. My lower motor neurons are not damaged. So, I don’t have a lot of voluntary movement (in my arms I do, but nothing chest down), but my reflexes work because they are lower motor neuron driven.

When my brain sends a signal (hey, your shoe is too tight…even though I can’t feel that)…my upper motor neurons cannot carry that message, but my lower motor neurons do. So my body will start spasming somewhere and I know to check and see why.

My spasms and spasticity are the result of me having an upper motor neuron injury. Those with lower motor neuron injuries do not deal with spasticity because their upper motor neurons are in tact.

Spasms are not controlled by me but is my body’s way of communicating to me that some sort of message is trying to come to my brain. It may be important and I need to get checked medically (like my hip being out of socket for a week and I never knew it except I had horrific spasms that wouldn’t stop so I went and got checked), or it may not be much and I just need to adjust something like move my legs, reposition in my chair or go to the bathroom. Here are a few favorites my brain likes to send my body messages about….

“Hey, you just rolled over a bump in the sidewalk.”

“Hey, your bladder is full.”

“Hey, you are sitting crooked and you are not comfortable.”

“Hey, your foot is too crooked on the footplate.”

“Hey, that water is too hot or cold.”

“Hey, the wind is blowing on your legs.”

“Hey, you just stretched out.”

“Excuse me…but…you moved without letting me know!”

“Hey, the doctor just hit your knee with a hammer.”

And on and on and on….

So….if you seen my hands or core or legs shaking and spasming or stiff as a board….it’s okay.

It is just my brain trying to send me a message…and you know I’m a talker! 🙂