Reprinted from The RSI Network - Issue 19 - Aug'94
Robert L. Kane, DC, CCUCS
Recently, medical research has been targeting the role of the cervical spine (neck) as it relates to upper extremity injuries (hand, wrist, elbow, arm, and shoulder). Specifically, the role of cervical biomechanics (the motion occurring at the joints of the neck) is now seen to play a significant role in RSI. Alterations in cervical biomechanics can cause muscles to tighten, joints to inflame, and nerves to become irritated. At times this may manifest itself as neck stiffness and/or pain; however, many times this condition serves simply as a primary asymptomatic "crush site" for a double crush injury. In other words, the neck problem may or may not be severe enough to produce neck symptoms but can still be significant enough to cause the muscles and the nerves going into the arm and hand to become irritated. This, in turn, renders the upper extremity anatomy more sensitive to injury from repetitive use (i.e. double crush). Some common conditions that may contain double crush components are carpal tunnel syndrome (CTS), tendinitis, tenosynovitis, myofascial pain syndrome (trigger points), chronic muscle strain, and bursitis.
Research studies using electromyography (a diagnostic test used to measure muscle activity levels) have shown that excessive tightness of certain neck muscles can cause CTS symptoms and abnormal nerve conduction studies. In addition, movements of the head and neck by the CTS patient were shown to increase muscle contractions in the arm and forearm. These studies propose that for individuals with neck involvement, the muscles and nerves of the upper extremity are primarily suffering from the effects of repetitive strain which have been produced by the crush site at the neck. Repetitive use of the upper extremity, combined with existing muscle strain and nerve irritation from the neck, cumulatively produces enough damage to create symptoms in the extremity. Perhaps this explains why some people develop RSI, while others performing similar intensity levels of repetitive motion at their jobs do not. Certainly it would explain why localized treatment at the site of pain is often ineffective in resolving these injuries.
Many patients are now receiving therapies for RSI of the upper extremity which include stretching of the neck muscles. However, medical research has shown that although stretches can be effective at improving RSI, these results are most likely to be temporary. At times, patients report a worsening of symptoms in the arms or hands when performing the stretches as well. What is often overlooked in both these cases is the presence of abnormal motion occurring at the joints of the neck preventing the muscles from permanently relaxing. Until the joints of the neck move properly, the muscles of the neck and arms will remain overworked and continue to produce crush sites for upper extremity problems.
Through recent medical advances in diagnostic technology, it has become apparent that most RSIs are actually a combination of several conditions superimposed on each other. In the last RSI Network newsletter, Peter Bower MD eloquently makes this point and further states that "Addressing just the painful part in therapy and not the entire neck to the fingertips is substandard treatment." The message is clear. The doctor of today must look at RSI as not one condition but as several related conditions. Diagnosis and treatment must be tailored to reflect the true nature of RSI. The role of the neck in RSIs must not be overlooked.
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Last Updated: 10/21/00