The Myth of the 'Pinched Nerve'

An interesting article in the science section of 'Sueddeutsche Zeitung' describes a new shift in the understanding of musculoskeletal pain. It is based on the recent congress on pain symptoms (Deutsche Schmerzkongress) in Duesseldorf and the article contains frequent quotations from the president of that congress, Dr .med. Kay Brune from Erlangen.

 

"The idea that pain in the motor apparatus is dominantly a consequence of 'pinched nerves' and could be ultimately freed by removing the bony or muscular obstructions, is now considered as old fashioned and no longer valid.. Neurophysiologists now assume instead that successful joint manipulation - similar to other physical treatments - reduces the pain by stimulating the nerve fibers which lower the excitability of the cell in the central nervous system."

 

Whereas in the past research and treatment of back pain had been predominantly oriented around biomechanical explanations ("pinched nerve",) contemporary models now seem to give much more emphasis on neurophysiological ("pain memory") aspects of back pain.

According to data published by the renown Emnid Institute, two thirds of all citizens complain of recurring pain in their locomotor system, 61 percent are impaired in their daily activities by it, and every third day of work disability is caused by back pain. Yet 85% of the chronic back patients are not treated sufficiently.

According to Kay Brune "the surest method against backache is no bed rest, no X-ray and no surgery. In the case of acute backache it is rather important to continue with the normal active life. Operations rarely lead to continuous improvement - on the contrary" says Brune. Because quiet periods contributed to make the pains become chronic. The most effective therapy against backache is therefore early mobilization. Once a person gets into the vicious circle of pain and rest it is usually hard to move out of it without medical help. If you reduce your physical activity too much the stability of your spinal column will get worse, which leads together with a bad posture to intensified pain.

But even without any wrong behavior acute troubles may become chronic. Every painful stimulus triggers electric impulses in the peripheral end of thin nerve fibers, which run to a coordinating point in the spinal cord. As a reaction to these impulses, carriers (neurotransmitters) are set free which as chemical 'messenger' give information to the central nervous system.

As nerve cells are able to learn, their way of function changes if they are stimulated either for a long time or repeatedly in the same way. According to Walter Zieglgänsberger of the Max-Planck-Institute for Psychiatry in Munich the intensity of the pain then increases, since the same stimulus then leads to a higher number of electric discharges in the spinal cord (which had been reported before in SZ 26.3.98). If the excitability of the nerve cells increases then also the 'receptive areal' increases which is the area which is sensitive to pain. Then suddenly not only the shoulder hurts but the whole arm. Sometimes these nerve cells produce pain impulses even though there is no real stimulus in the periphery. Similar neural mechanisms have recently been accepted as a basis of the 'phantom limb' pain which amputees frequently feel and which had not been understood before.

Not all persons develop a chronic illness as a result of acute pain experiences. These persons are protected by systems within their own body which dampen the increased excitability of the cells in the spinal cord. In the neighborhood of these excitatory fields there are also areas which hinder the activity of nerve discharges as soon as they are stimulated. And how excitable a cell is depends also on hormonal and immunological factors.

'These neurophysiological findings are very important for the therapy' says Hermann Locher of the 'International Association for Orthopedic Pain Research' (IGOST). The idea that pain in the motor apparatus is dominantly a consequence of 'pinched nerves' and could be ultimately freed by removing the bony or muscular obstructions, is now considered as old fashioned and no longer valid.. Neurophysiologists now assume instead that successful joint manipulation - similar to other physical treatments - reduces the pain by stimulating the nerve fibers which lower the excitability of the cell in the central nervous system. Therefore the common assumption of most physicians that one should not manipulate more than three times repeatedly isn't valid any more.

On the contrary: In order to achieve a permanent reduction of the increased excitability, the pain causing stimulus must be interrupted until the nerve cells have 'forgotten' it. In therapy one should not wait until the pain returns, but one has to intervene before that. 'Therefore today we start to treat more individually than in former times, specially in regards to the frequency of manipulation' reports orthopedic doctor Hermann Locher. For chronic pain patients the 'serial' therapy has been established in which some patients are treated even daily for a while. In his opinion acupuncture can be used in the same way. Furthermore this new neurophysiological modell presents an understanding on the molecular and micro-anatomical aspects about how this method could function.

For Zieglgänsberger acupuncture and electrostimulation are methods which follow the same principles as manual medicine or massage. In his opinion the new neurophysiological concept explains also the influence of psychological and social factors on chronification of pain. Already in the beginning of the 90s US-scientists published a study which showed that for the prognosis of the progression of backpain symptoms of a given patient the situation at work is more important than the severity of the acute pain.

The article - written by Marcela Ullman - appeared on Nov 17. 1998 in the science section of the 'Suedddeutsche Zeitung'. Translation and summary into English by Karin Paleczek.