Years ago a landmark study proved that not all pinched nerves hurt. By looking at multiple cadavers, researchers found many flattened, pinched, crushed nerves that caused no evidence of pain in the person's medical records (Neary and Ochoa 1975). That really puzzled the medical community because the popular thought, at the time, was that all pinched nerves hurt. Since that theory was disproven, scientists have been trying to explain why some nerve damage hurts and some does not.
Within the past 15 years, many studies have shown the effects of inflammation on the nerve. Without any source of physical, mechanical pinching, a nerve can be damaged by the inflammatory chemicals. Such chemicals are equivalent to throwing acid on a nerve. That is why steroid injections work. The steroids block the chemical reaction and cool the nerve. However, some people know that even injections do not help all types of nerve pain. So, there must be more to this puzzle; inflammation is not the only reason why some pinched nerves hurt and some do not.
Another puzzle piece lies deep within the central workings of the nervous system: the dorsal root ganglion, the spinal cord, and the brain. In a process called sensitization, the switch is flipped, the alarm is triggered and the nerve is set on fire. Sometimes this switch is not turned on; hence, not all damaged nerves hurt. One group of researchers has been instrumental to define the parameters of the sensitive nervous system and this sensitization process. The NOI group (Neuro Orthopaedic Institute) in Australia is trying to get everyone to wrap their brains around some new concepts about pain. Eventually, major conceptual shifts will change how the world thinks about pain and treats pain.
In a landmark book, Explain Pain, David Butler and Lorimer Moseley take a reader through examples like phantom limb pain to point out that physical damage to a nerve is not always necessary to cause pain. Even when a limb is gone, pain and sensation in the "phantom" limb is still felt. If pain is felt even in the absence of a peripheral nerve or limb for that matter, the central nervous system must be involved in the pain experience. They compare the nervous system to a sophisticated alarm system that has sensory "reporters" sending "danger messages" to the brain. In this sensitization process, they explain that nerves "backfire" and the alarm system becomes altered enough to "smudge" the signals. If one adds in a "thought virus" or two, the entire nervous system can become one angry alarm that will not shut off. Imagine a car alarm that will not shut off. Annoying and relentless, that is what nerve pain can be like; no pinching, squishing or crushing required.
Why is it so important to understand these concepts about pain and the sensitive nervous system? Some things may be misdiagnosed without a complete understanding about pain. In a recent interview with David Butler, he commented about the misdiagnose of painful conditions like certain types of tendonitis which are really forms of nerve pain such as "achilles tendonopathy (sural nerve), patellar tendonopathy (saphenous nerve) biceps tendonopathies (median nerve). It is not only tendonopathies that are misdiagnosed but other common pain states (diagnoses) are likely to include changes in peripheral and or central nervous systems , for example plantar fasciitis (plantar nerves) and tennis elbow (radial nerve)." For further evidence of how understanding the nervous system can lead to innovative solutions, with permission from the NOI group, here is a story about a poor chap with hand and elbow pain.
"I took over the management of a young man one year after he had cut his thumb (over the distal palmar surface) at work. The cut subsequently became infected and took a long time to heal. He developed mild stiffness in the DIP joint however his main complaint was pain with any kind of gripping activity, and this pain had somehow spread into the elbow...
He had mild flexor policis longus weakness and pain with any active thumb flexion. Passive thumb flexion was pain free. I was unhappy to see that he had received massage and mobilisation to his thumb and forearm for one year following a relatively minor injury and was still complaining of pain. Upon further assessment pain in the thumb was reproduced with median nerve testing and was eased with thoracic mobilisation and stretching exercises. This man was on work cover and was only entitled to one visit per month so I sent him away with a new set of exercises which focused on thoracic mobility and median nerve gliding and tensioning (with and without shoulder shrug). He came back in two weeks to let me know that his pain had almost abolished and it was only bought on now by strenuous activities such as carrying heavy buckets and surfing for over one hour! He was able to "warm" up his arm and thumb by doing the gliding exercises and ease or prevent the pain if he felt it coming on.
Two months of this approach and he was cured!!"*
Could this chronic painful condition from a sensitized nerve have been prevented? According to David Butler, "The notion of preemptive management of chronic pain and stress has hardly been addressed. And only recently have some of the skills used in chronic pain management been used in the acute stage. Our view is that much chronic pain can be prevented with appropriate management in the acute stage. This has to include threat reducing education and control of nocioception." Wow, imagine a day when we can prevent chronic pain. Even if a nerve is "nipped" (as David Butler likes to say because such terminology is less threatening) or not, someday pain can be prevented because not all pinched nerves have to hurt. Stay tuned because new research is surfacing. This new information will likely contain information about stress science and immunology. Once the entire puzzle is put together, everyone will know how to Explain Pain.
For upcoming events to learn more about nerve sensitivity check out www.noigroup.com. The NOI group runs about 100 seminars a year in the area of neurodynamics and pain management.
Thank you to David Butler for his kind contribution.
Coppieters MW, Butler DS 2008 Do sliders slide and tensioners tension? An analysis of neurodynamic techniques and consideration regarding their applications. Man Ther 13: 213-221