(D) WHERE IS THE PAIN COMING FROM?
The tissue origin of low back pain and sciatica: a report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia. Kuslich SD, Ulstrom CL, Michael CJ. Orthop Clin North Am. 1991 Apr;22(2):181-7.
“This article summarizes the results of 193 consecutive patients during the period from 1987 to 1990. All patients underwent decompression operations for herniated disc or spinal stenosis. We used an anesthetic technique known as “progressive local anesthesia…” We stimulated each successive tissue by means of mechanical force using blunt surgical instruments or the application of electrical current… The patients were fully awake or only lightly sedated.”
“Sciatica could only be produced by stimulation of a swollen, stretched, or compressed nerve root.”
“Back pain could be produced by stimulation of several lumbar tissues, but by far, the most common tissue of origin was the outer layer of the annulus fibrosus and the posterior longitudinal ligament.”
“Buttock pain could be produced by the simultaneous stimulation of the annulus and the nerve root.”
“The normal, uncompressed, or unstretched nerve root was completely insensitive to pain.”
“Stimulation of the compressed or stretched nerve root consistently produced the same sciatic distribution pain as the patient had experienced preoperatively. In spite of all that has been written about other tissues in the spine causing leg pain, we were never able to reproduce the patient’s sciatica except by finding and stimulating a stretched, compressed, or swollen nerve root.”
“The annulus was exquisitely tender in about one third of cases, moderately tender in one third, and insensitive in the remaining one third operated for herniated disc or stenosis… …They did, however provide an explanation for the observations made by other authors that some individuals with disc protrusion are asymptomatic, while others are acutely tender.”
“Referral of pain depended upon the exact site of the annulus being stimulated. The central annulus and posterior longitudinal ligament produced central back pain. Stimulation of the right or left of center of the posterior longitudinal ligament directed pain to the side of the back being stimulated. This correlates with the finding of back pain on the one side or the other when a “bulge” in noted on CT scan on that side of the midline.”
“In general when the posterior annulus was tender, the posterior longitudinal ligament was also sensitive.”
“The [facet joint] capsule was sometimes tender, but when it was, it referred pain to the back, or very rarely the buttock–never the leg… The facet synovium was never sensitive. The facet articular cartilage was never sensitive.”
“Could it be that repeated contact between the superior facet and the disc causes an irritation that the patient interprets as low back and the physician interprets as facet syndrome?”
“In spite of all that has been written about muscles, fascia, and bone as a source of pain, these tissues are really quite insensitive.”
“These observations cast doubt on the effectiveness of several commonly used forms of exercises, magnets, toe-tickling, manipulation, muscle relaxants, anti-inflammatory medicines, psychotherapy, and even some surgical procedures. Perhaps we should be spending more time learning how to effectively treat the true source of spinal pain, and less time massaging, manipulating, heating and cooling tissues that have little to do with the production of low back pain and sciatica.”
“Based on the evidence above, we may find a really effective treatment for low back pain and sciatica when we learn how to decompress a nerve atraumatically and, at the same sitting, treat the painful disc by stabilizing the motion segment atraumatically. Such a procedure does not currently exist, although we and others are in the process of developing the technology.”
That’s a lot more quotes than I usually try and take from a single article, but this study was fascinating and covered so much that has been debatable in the treatment of low back pain, and it fits in so well with the biomechanical research on spine degeneration. The annulus of the disc (tensioned by spine flexion) is very frequently a source of pain, though for about third it isn’t. The supraspinous ligament (also tensioned with spine flexion) was painful 25% of the time. Compressed and swollen nerve roots, as you would expect in the later stages of spine degeneration where most likely flexion induced disc herniation resulted in significant disc deflation and pinching of the nerve root between vertebral bone and associated bone spurs (the nerve immediately where it exits the spinal cord). Sciatic pain did not seem to result from pinching of the sciatic nerve anywhere near the piriformis muscle, which would explain why stretching the piriformis muscle for sciatic pain never worked very well, and rarely worked at all in my experience.
I almost fully agree with the authors conclusions on why so many common treatments are ineffective. Interestingly though they said they were developing non-invasive technology to treat low back pain and sciatica, they never published another paper on the topic and it’s been almost 30 years since this paper was published. However, I think we are there now, however with prevention being considerably more effective than treatment after the fact. Though both prevention and treatment are of similar means, to stabilize the disc during the days activities by having both good fitness and good awareness as to what what causes ligament, annulus, and nerve compression and establishing good awareness to avoid those habits. All of which is embodied in my very specific Spinal Flow Yoga™, treating, and better yet avoiding “the true source of spinal pain.”