Neuromechanics Weekly: Installment 2 (Now aren’t you lucky to have so much neuro in 1 week!)

FEEL THE PAIN: PART 2

The Character of Pain

In today’s post we hope to help you better understand your pain or the pain that someone else describes to you. The character of the pain can tell you much about what tissues are involved and what might be going on behind the scenes. Understanding the anatomy and physiology of the parts is critical.  Thus, this post is going to be a little latin/medical word heavy for some of you….. but trust us, if you spend just a few extra minutes championing these words and owning the concepts below you will forever be better at what you do. Or at the very least, better understand your own pain.

In prior post in this series we talked about the pain producing tissues being derived from one of the primordial tissues, the endoderm, ectoderm or mesoderm. And if it is from  the mesoderm, from which of the 3 layers of the somite is it originating ? The sclerotome, the dermatome or myotome? (The mesoderm is the middle embryonic germ layer from which connective tissue, muscle, bone, and the urogenital and circulatory systems develop.)

As we discussed yesterday, pain usually has one of four qualities: burning, aching/throbbing, sharp/stabbing, or electric/shooting. Each one tells us something about where it is coming from.

Remember the Krebs cycle? How about glycolysis? What was one of the end products of glycolysis? Lactic acid. Your ability to recycle it and make it into oxaloacetic acid and stuff it back into the Krebs cycle determines your aerobic capacity. When lactic acid builds up, we get muscular inefficiency due to the drop in pH (initially this helps, but too much of a good thing creates a problem), The result? Burning pain. Burning pain is the burn of glycolysis, or muscular overuse.

Aching/ throbbing pain is that deep, boring pain, like a toothache in a bone. It is the pain of the mesoderm, or what is often called sclerotogenous pain. Aching/Throbbing pain is the pain of connective tissue dysfunction (remember that connective tissue is bone, cartilage and collagenous structures like ligaments and tendons). Throbbing pain can sometimes be vascular in origin, as the connective tissue elements of the vessels (the tunica adventitia to be exact) is stretched (which contains a perineural plexus; think about the pain of a migraine headache).

Shooting/electric pain is the pain of the ectoderm. Think about when you hit your ulnar or peroneal nerves and get that “electric shock” sensation. If you ever have had a herniated disc, you know this pain first hand; sharp and shock like. This pain often travels in the distribution of a nerve root or peripheral nerve. 

Sharp/ stabbing pain is the pain of acute tissue damage to one of the 3 layers of the somite (the dermatome, sclerotome or myotome). Think of a sprain (sclerotome) or strain (myotome), or the pain of a shingles outbreak (dermatome). Sharp/stabbing pain is the pain of acute tissue damage.

Keep in mind there is often overlap of pain types, which mean that there is more than one tissue crying out for help (the burning pain in the left hip from gluteus medius insufficiency, combined with the dull, achy pain in the medial knee, from poor control of internal rotation of the thigh).

Pay attention to the character of pain, as it often provides clues to the tissue of origin.

The Gait Guys. Explaining it so you can understand it, one pain free stride length at a time.

Ivo and Shawn

Neuromechanics Weekly:

FEEL THE PAIN: PART 1

Pain Producing Tissues

What usually brings people in to see you or us? Sometimes, it is the desire for better performance, but most often it is pain. We see it daily in our offices. You see it daily in yours. In this installment of Neuromechanics, how about we characterize some of what we are seeing?

We like to think of pain as having one of four qualities: burning, aching/throbbing, sharp/stabbing, or electric/shooting. Each one tells us something about where it is coming from. Before we talk about that, we need to assess  “What is the pain producing tissue?"  To understand this further, we must delve deeper into tissue types.

We may remember from embryology, around the 3rd week of development, the embryo becomes trilaminar (three layers) forming, the endoderm, the mesoderm and the ectoderm. The endoderm becomes most of our organs (called the splanchnotome), the ectoderm becomes the nervous system, and the mesoderm becomes the muscles, ligaments and bones. The mesoderm coalesces and becomes blocks or segments of tissue called somites.  These somites have 3 distinct parts: the dermatome, the myotome and the scerotome.

The dermatome becomes the skin, with it’s segmental innervation (the spinal cord level that supplies that area of skin). Think about when someone has an outbreak of shingles, which often follows a spinal nerve root distribution. We often test sensation along both dermatomal distributions (segmental) and peripheral nerve distributions (with contriobutions from many segmental nerves).

The myotome becomes the muscle and the segmental nerves which supply it. Each segmental level usually corresponds to a function (S1 does plantarflexion of the foot, L5 does dorsiflexion of the foot, etc). This is one of the reasons we muscle test, to tell us which segments may be involved in a problem.

The sclerotome becomes the bone, ligament and tendon supplied by one segmental level (ex. C5 does most of the upper humerus, lateral scapula and clavicle and shoulder capsule). It is what causes the pain associated with sprains or fractures. This is the pain of connective tissues (remember, connective tissues connect muscle to bone AND make up the ultrastructure of the muscle itself!) This is one of the most common pains we encounter in a clinical setting.

Knowing the tissue of origin often leads to a more specific diagnosis etiology of why your client/patient (or YOU) are having a problem.

Next time we delve deeper into pain. Until then, we remain, 2 good looking, aging, nerdy bald guys, Ivo and Shawn.