S7E13: Different Types of Nerve Damage

Do you wonder if you're the best version of yourself? This is a question we seek to answer in this podcast. We reveal information that helps you recover your health and become resilient. Modern life makes us fragile. Our diet, lifestyle, environment set us up for failure. We do not accept this. We seek optimization. We strive to become dynamic. Hey, what's going on? Dr. Chris here, and today I want to talk about nerve damage, the Different types, what it is. You hear being thrown around, I've got nerve damage. Well, what does that really mean? So let me see if I can clear this up. So first off, we have to make a distinction between the central nervous system and the peripheral nervous system. The central nervous system is your brain and spinal cord, and then everything else is the peripheral. So all the nerves that come from your spine to your arms, your legs. So think of like the ulnar nerve or the sciatic nerve. Those are the peripheral nerves. That's what this is going to be mostly about. But let me give you a little interesting analogy one of my professors gave to us in grad school, which kind of took me by surprise because grad school is very serious and it's all about professionalism. And he made this analogy that was not exactly professional, but it did the trick because I still remember it. And it goes something like this. This is how you can determine between central and peripheral. So think of the central nervous system or the brain as A mother. The nerve, the peripheral nerve, that is, is like a promiscuous daughter. And the muscle is like the boyfriend who drives a Mustang. I think that's what— that's the muscle, right? So if you have— if you eliminate the mother, so say like a stroke, in other words, and you're only left with the promiscuous daughter and the muscle, you get, you know, what's called a lot of facilitation, a lot of activity. So in the stroke world, that's called Spasticity. So if you see someone kind of holding their arm in a clenched fist and bent elbow, that's spasticity. That's what happens with central nervous system damage. With peripheral, it's kind of the opposite. So if you— the mother's still there, right? But now the daughter is no longer around. So it's just the mother and the young boyfriend, nothing happens. So you get flaccidity or a muscle that doesn't work. So that'd be kind of an extreme version of peripheral nervous system damage. And we have ways to test for this. So— If, if you have a central nervous system issue, your reflexes will be a little bit hyper on one side and just the opposite. If it's a peripheral nervous system issue, then you'll have a decreased sensation, hypo reflex. So that's how, as physical therapists, that's just one clue for many other things that we can use to determine where the issue is. But let's go into the different classifications of damage. So back in the '40s, There was a neurologist, Herbert Seddon, who came up with the Seddon classification. So he kind of put nerve injuries into 3 major categories: neuropraxia, axonotmesis, and neurotmesis. Neuropraxia is the, the mildest form and definitely the one you'd want. Think of it like a kink in a garden hose, that the hose is still intact, but the flow-through has been interrupted. So this, this will happen after sleeping in an awkward position or a prolonged compression of a nerve, like sitting on a hard surface, sitting on the toilet for too long. Or so it's common. In fact, there's something called Saturday night palsy, which is kind of a funny name. The idea on a Saturday night, maybe you've had some drinks with friends and you fall asleep and you wake up on the couch and suddenly you can't lift your wrist, your wrist up. That's because you've been compressing the radial nerve and because maybe you were drunk, you're not getting the Sensation from your body that you should move, right? Because pain is your body's way of requesting change. So the drunken stupor overrides the signal from the body and you've compressed the nerve and now you have neuropraxia. So your typical symptoms with this could be numbness, tingling, burning, weakness, and temporary loss of the muscle. But this has the best prognosis and you can get over pretty fast and you might not need any kind of intervention with this at all. So the next class is the axonotmesis. So nerves have what are called axons. You get the cell body of a nerve. So you got a cell body on either side and then a long tube between the two. That is the axon. Now, in axonotmesis, the axon itself has been injured and has been disrupted. However, all the connective tissues that surround the nerve are intact. So, um, this one, that matters because the portion of the axon downstream from injury can't really survive. So you get something called Wallerian degeneration. So what that means is essentially cellular cleanup. So after the area where the axon has been damaged, the rest of it will sort of shrivel away and die and make room for new growth. So that's the good news, is that most of the time the nerve can regenerate. Uh, it just is slow. It's something like, um, a millimeter per day given the right environment. So there's a lot of variables to that too, such as the severity of the injury, your age, your health. Um, do you have diabetes? Diabetes slows down everything. So there's a lot of variables to how fast it grows back, but at best, roughly 1 millimeter per day. And by the way, that's why an injury like near the hand or foot may recover differently from injury occurring much higher up the ladder. And the last category is a neurotmesis. This is the most severe. That's where not only is the axon disrupted, but all the connective tissues and support structures around it are also damaged. So now, uh, the— it doesn't have a way to grow. It doesn't know how to grow, and it doesn't typically repair on its own. So this is where you're definitely seeing a neurologist, and surgery may be warranted. So what do you do? You know, first stop would be a physical therapist, in my opinion. Most physical therapists that are decent can pick up on these things. They can tell, is it peripheral or central? We can look for your reflexes. We can look at your strength, your range of motion, your sensation, right? Nerves are, you know, these types of nerves at least are two-way streets. They do motor control and they do sensation. We can look at nerve sensitivity. There's something called a slump test and there's tension tests that we can do to see if the nerve is involved. And then you may be referred to a neurologist for an EMG study where they check the strength of the signal of the nerve. Another thing that's important to point out is the time for recovery. So this is not the same as an injured muscle. Muscles have good blood supply, so they tend to heal much faster. As I stated before, so you had that axonotmesis, we're talking about a millimeter a day at best. So really our goal is we're trying to identify where the issue is, alleviate it, like say it's a compression of the spine, alleviate that. And then create the most optimal environment for the nerve to heal. A ship in harbor is safe, but that's not what ships are meant to do. What does this mean? It means exposing yourself to difficult situations so you become resilient. If you need help building resilience, check out our flagship program called Physiologic Flexibility. This is a 3-month do-it-yourself program that teaches you how to maximize your homeostatic regulators such as your pH, Blood glucose, O2 and CO2 tolerance, and temperature. We give you specific action items through the program with the goal of becoming antifragile. If you want to become the inspiration for your friends and family, this is the program for you.