There’s always that impressive moment when you are assessing someone and trying to replicate their pain pattern and you perform the all important ‘pressure point find’. You listen patiently to their symptoms and their description and the nature, location and severity fo the pain, all the while forming an opinion in your head. To then simply say to them in a break in the conversation ‘does this hurt here’ and they recoil from your touch and look at you incredulously as if you have just robbed them of their first born child. Its a moment that has a slight sense of satisfaction in that you have been able to pinpoint the issue and the point from which all else radiates!
Now it’s rare to be able to do this quite so succinctly and easily and there is always something sneak lurking within a pain pattern or injury pattern. But it does stand true that there are certain patterns and elements that present in the anatomy that allow us to pinpoint exact locations of symptoms and tie them directly to a specific point and issue located in the body. Enter the spinal column!
Dermatomes are areas on the skeleton that relate directly to a specific and individual spinal segment. The areas designated on the arms and legs relate directly to a single spinal nerve and being able to palpate or pinpoint this area where a client may be experiencing pain, numbness, tingling or other type of ‘nerve pain’ can be traced directly back to that one location in the spine that corresponds to that singular nerve and where it exits the spinal column. Often we look directly to the thoracic cage and view it as a series of discs that stack on top of each other. Pain or sensation that is consistent throughout this area would normally be related to a single spinal nerve ennervation. Likewise on the appendicular skeleton (arms and legs) patterns can be identified although the nature of these patterns are more cylindrical and less obvious in these areas.
What this means is that pain experienced wholly within these patterned areas can be traced back to a single spinal nerve and this means that we could be looking at a spinal occlusion. Where a disc space may be inhibiting free movement of the nerve, a vertebral body may be slightly out of alignment and not necessarily occluding or pinching the nerve, but touching it enough to make it fire. For example if a spinal segment is slightly askew to the L, a person moving their spine towards the L in a toros bend laterally, may create a situation where the nerve is being compressed (for want of a better term) and this makes the nerve fire and gives us the nerve pain in the dermatome area. If we can pinpoint the area and establish the single dermatome we can start to look directly at it’s corresponding spinal location. It doesn’t even have to be a full impingment but any movement that sees the vertebral space being reduced can trigger the nerve to fire if the movement makes the nerve compressed.
These maps are like a pallete of a painter. If we find the consistent pattern then we can be sure to a certain extent that our first location of investigation would be the corresponding nerve root. These patterns are not linear on the appendicular skeleton as they are on the torso and so it does take some investigation to ascertain exactly where the pain is most prominent. You can also have more than one nspinal segment being affected which would result in a ‘multiplicitous area of ennervation’. That is a combination of dermatomes being present.
The type of pain that is experienced is also of great importance. Nerve pain is different to muscular pain. Nerve pain has a different nature to acute pain and can be characterised by a tingling, numbness, prickly heat or radiating sensation. Its not necessarily made better or worse from movement and is more persistent in nature. Sharpness or wincing pain is not usually the modus operandi of nerve pain and it is more associated with a dull ache or numbness.
Dermatomes can also correspond to spinal nerves when we look at communicable diseases. Viruses such as chicken pox and herpes can lie dormant in nerve root ganglia (bodies of nerve cells) and become active when irritated or stimulated. The outbreak of chicken pox in particular areas of the skin can be attributed to the virus lying or residing directly in that nerve root location and hence the dermatome becomes the affected area.
So when we are faced with pain that may radiate along the lines or patterns consistent with dermatomes, you may find a therapist asking more about your spine than your foreleg or hand. It comes down to assessing the origin of the pain and identifying patterns that would make an assessment along the lines of a spinal nerve root more vital to get treated than in rubbing ‘the sore bit’.
Things aren’t always readily identified in the area that is affected. The body is very good at being sneaky and displacing the origin of pain.