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Reprinted from The RSI Network - Issue 19 - Aug'94
Robert L. Kane, DC, CCUCS
David A. Browning, DC
August 1994
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.
References
* Pronsati, Michelle P: Neck Muscles Play Part in Carpal Tunnel Syndrome. Advance for
Physical Therapists, July 6, 1992.
* Korr IM: Proprioceptors and the Behavior of Lesioned Segments. Osteopathic Medicine.
Acton MA, Publication Sciences Group. 1975 pp. 183-199.
About the Author
Robert L. Kane, DC, CCUCS (74021.740@compuserve.com), and David A. Browning, DC. Dr. Kane
is a private practitioner at the Amalu Chiropractic Center, Redwood City CA (415)361-8908.
Dr. Browning is a private practitioner at the Browning Family Chiropractic Center,
Pleasanton, CA (510)484-4647.
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