Brief Answer:
The Cord is pretty well protected
Detailed Answer:
Hey there! Thanks for following up! Sorry for taking so long to get back to you. Your day is my night. Sorry bout that.
So, lets try and give ourselves some grounding first in the neuroanatomy of the spinal cord. I really wish I could upload a picture or two, but the system is pretty limited as of now. So i want you to imagine a single copper wire. Think of that as a single nerve. It spans from the brain all the way down through the cord all the way down to the feet (now that's not the way it really is.. but humor me). This single wire has insulation all around it to make sure it doesn't short with other wires that bundled with it. Now take a few thousand of these nerve/wires and bundle them together in some plastic sheathing.. That forms a tract of nerves. One such tract may send command impulses to a part of the body... say the left arm or the right leg.. Take about 10 of these tracts and pack them together in a triple layer of sheathing that is suspended in a fluid which acts as a shock absorber... Take THAT entire Cord and encase it in a bony cage called the spinal column.. and now you start to see the architecture of the spinal cord..
It is INCREDIBLY well protected and teh only way to affect the individual 'wires' is to really press down on the cord and press hard so that it gets through all that packaging. It's really tough to cause an injury which presses down on the cord so that it causes
myelopathy.. especially when you consider that that spinal column is also braced by paraspinal muscles and tendons and fat.. etc etc...
That having been said lets get to your questions.
A) "if the arm/
neck pain of a
radiculopathy is, in fact, "a symptom of myelopathy" and if that arm/neck pain is improving greatly compared to five weeks ago, could this mean there is less pressure on the spinal cord now than there was previously."
Unfortunately not.. in a partial compression (which i am assuming you have) the parts of the cord that are being pressed against are going to be superseded by the other 'wires' in the same bundle that are NOT being pressed. So the nervous system modulates the signaling so that fewer impulses travel through the affected segments and more of those impulses travel through the unaffected ones.. this can keep going on until the entire bundle is affected.. then the redundancy fails and the entire bundle fails.
Physical therapists are masters of 'retraining' the CNS and the cord to send impulses through unaffected nerve groups so that the muscles on the effector end, end up working just as well and the sensory receptors that are damaged are progressively ignored by the insular cortex (the part of the brain that filters out the noise and allows only allows sensation to get up to conscious levels).
So in a nut shell. Yes..
physical therapy can vastly improve your performance and symptoms, but it will not ultimately change the pathology behind the problem. The cord will continue to be compressed.
B. "What conclusions can you draw from the fact that I have
spinal cord compression and an abnormal signal; yet no neurological symptoms, what are all the possibilities?"
Simple, you're nervous system is robust and built in with plenty of backup. The MRI takes an image and shows whats THERE.. but it will not show the functioning of the cord in those high signal areas.. Also, i haven't seen your scans.. so i have no idea WHICH bundles are affected.. It could be that the motor tracts are fine and only the sensory tracts are affected (all of the pain.. with non of the physical
disability.. no obvious myelopathic symptoms). It's pretty tought to have a compression that affects ONLY 1 bundle.. they are packed in there pretty tight.. but i've seen it happen.
C. "Is it possible to have pressure on the cord and a abnormal cord signal and to "not" develop neurological symptoms; which would indicate relative stability for 25 years?"
Ohh yes. the injury you had 25 years ago was an injury to a system that had healthier bone, better muscle mass, more collagen in the tendons and better
muscle tone.. over the last 25 years.. the bones have become less dense.. the muscles weaker.. proteins in the tendons degrade and are not repaired and in general we suffer from degeneration of the discs and the vertebrae and surrounding structures.. so as time passes.. an injury that was SUBclinical at first can gradually show up with clinical symptoms.... That would also explain why the PT is helping you... you are basically reversing some of those age related changes (namely the muscle tone and muscle bracing)
In the end.. I think you are going through normal degeneration of the spinal column coupled with an injury that is now beginning to surface. Not the best situation i know.. but that gives us a plan to deal with it.. Turn back the clock.. do whatever you can to strengthen the musculature of the neck.. physical therapy is the key!
It's fun talking to you. Thanks for the follow-up. I hope I'm making sense.. this stuff can get pretty dense. For any further clarification, don't hesitate to contact me.
Vin