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Carpal Tunnel Syndrome and Repetitive Stress Injuries

By Siana Goodwin

Copyright 2003. Associated Bodywork and Massage Professionals. All rights reserved.


On a daily basis, massage therapists across the country assist their clients in the prevention of, and recovery from, carpal tunnel syndrome (CTS) and related repetitive stress injuries (RSI). Let's take a look at the anatomy and biomechanics of CTS and related syndromes, and through our understanding of the structural and behavioral origins of this disorder, find ways to prevent it from "impinging" on your own body.


Understanding Structure
Structurally, three sides of the carpal tunnel are formed by carpal bones, and the fourth side by a broad ligament. The bellies of the prime muscular movers of the hand lie in the forearm. The force of these muscles is delivered to the hand by long tendons. Eight of these tendons pass through the carpal tunnel, along with the median nerve. If any one of these nine elements becomes slightly inflamed, it puts pressure on all the other elements, resulting in more inflammation for all members of the group. A vicious cycle begins.

Anti-inflammatory medication may be useful, but it is difficult to deliver the pharmaceutical to tendons because of their low vascularization. A surgical approach is to lengthen the ligament forming the palmar boundary of the carpal tunnel, thereby increasing the volume in the tunnel. This surgery is often quite successful, but I believe prevention is preferable to surgical correction.

It's very common for people to refer to all RSIs of the hand and arm as "carpal tunnel." I have even heard injuries to the elbow being called "carpal tunnel in the elbow." The specific condition of CTS is an impingement of the activity of the median nerve. Presence of CTS is identified by electromyography, which determines the conduction capacity of the nerve. Impingement of the nerve results in pain and tingling in the hand, and muscle weakness in its intrinsic muscles, especially the flexor and opponens pollicis. In severe cases of CTS, these muscles atrophy.

There are conditions that can precede the onset of CTS and these can also produce symptoms of pain and numbness. Usually these are caused by prolonged muscle tension resulting in the restriction of blood flow. When this occurs, not only do muscles and nerves not receive the nourishment they need for repair, but the removal of metabolites from normal muscle functioning is also lessened. The result is edema of surrounding tissues and increased pressure and tension in the area. Many RSI and CTS problems occur in a cycle of tension: restriction of blood flow, edema and consequent further restriction of movement -- all potentially leading to severe problems.

The muscle tension that's part of RSI may be due to repetitive movement or it may be a somato-emotional event resulting from psychological stress. In the long cycle of micro-injury that produces symptoms of RSI, bodywork can be of great help in reducing tension and edema, increasing blood flow and encouraging different movements that may reduce or reverse painful symptoms.


From a Rolfer's Eye
Rolfing can be especially well suited for this kind of work because of its emphasis on altering patterns of movement and strain throughout the entire body, as contrasted to working only for symptom relief. Rolfers are trained to consider the whole body in looking for an overall pattern of tension or restriction in movement, of which the complaint -- RSI or some other condition -- is one manifestation. Thinking about the anatomy of the upper limb, for example, illustrates the sense of this. In the hand, while there are numerous muscles that facilitate finger movements (having origins and insertions only in the metacarpal and/or phalangeal bones), the flexors and extensors of the digits and wrist have their origins either in the bones of the forearm or the arm itself. The structural relationship of the forearm to the arm is, of course, affected by the muscles that cross the elbow. Now we can see a relationship between the muscles of the wrist and those of the arm. The action of the muscles of the arm is also affected by the position of the arm in its socket, relating to the muscles that have origins in the scapula; their function is affected by the muscles spanning the scapula and torso.

From another point of view, tracing the path of the nerve supply to the wrist and hand through this overlapping complex of muscles back to the origins of the brachial plexus in the neck will demonstrate that compression of the median nerve (or radial or ulnar nerve) may occur at any point in its length. To the eye of the Rolfer, a complaint of pain in the hand or wrist may have an origin anywhere along this path. And the manner in which a Rolfer palpates and gathers information from the body, through the web of fascia, can lead her to feel connections related to the complaint, but perhaps distant from it. Two elements are important in this equation: the connectivity of the tissue and the layering of tissue in the body.

Anatomical studies from the West emphasize the separation of muscles and tissues, and we are prone to think of the body as being composed of separate parts stuck together in some mysterious way. However, fascia is a continuous web throughout the body, and it is possible to feel the connection between distant restrictions through it. If a Rolfer or other bodyworker, instead of addressing a tight muscle, can experience the corresponding patterns of tension in the fascia, whole patterns of concurrent strain throughout the body will present themselves. Similarly, the concept of working in the fascial web allows distinctions within muscles, which appear in the concept of layers. Since fascia surrounds not only the gross structures of muscles, organs and bones but also muscle bundles, fasciculi and even individual muscle cells, it is possible to develop a refined approach to working at layers of tissue. The body can be experienced through touch, not only as a collection of muscles, but as infinite layers of connective tissue, any one of which will contain muscle fibers as well as portions of other fascially-encased structures. It's not unusual to find restrictions at a particular layer within the limb, which may not be present at other layers. For instance, the surface muscle tissue of the wrist flexors may appear quite soft, easily compressible to the touch, but hard at a deeper level. What we think of as a muscle that we could dissect from the arm, often has differences in consistency within it. It is in layers of tissue that the differences are felt.


Putting It Into Practice
It was my background as a Rolfer, in looking for overall patterns in the body, and in experiencing the body in fascial layers, that allowed me to make some connections between different phenomena I observed while working at Starkey Laboratories in Eden Prairie, Minn. Starkey -- one of the world's largest manufacturers of custom hearing aids -- was plagued with a high number of repetitive stress injuries, including carpal tunnel syndrome. My job was to reduce their employee incidence of RSI. When I first started, I assumed it to be entirely a problem of the wrist, since that is where the median nerve supplying the muscles of the hand is most vulnerable. But as I worked and studied more, I found a variety of different factors were at play in the injuries people were suffering.

While many of the employees had pain and numbness of the hand or fingers associated with RSI, each had different kinds of jobs. Some were office workers who used computer keyboards, while others were technical workers involved in manipulating small objects by hand or with tools, often kneading or squeezing compressible material or constantly moving their hand between pronation and supination within a small range of movement. In addition, many of these latter employees worked in a confined posture, while constantly gazing into a microscope.

As a result of my work, I found the following conditions also involved in complaints that qualified as RSI syndromes:

Tension in the cubital and proximal flexor compartment associated with continuous flexion of the elbow and sometimes associated with repeated movement between pronation and supination.
I consider this to be overworking of the biceps, especially irritation of the distal tendon, from continual small movements. From the viewpoint of fascial consideration, disturbances or stresses within fascial structures may also be important factors in RSI. Tension can be created in the fascia of the flexor compartment because of the attachment of the distal biceps tendon. Besides attaching directly to the radius, it also spreads out into the flexor fascia in an aponeurosis. If we consider that tension in the fascia can create stress on muscles, it is possible tension in the biceps attachment can produce tension in the fascia to which it is attached. This may contribute to tension in the overall flexor compartment.

Restriction of supination.
Most work with the hands is done from a pronated position. One of the observations of Rolfing is that when a particular position is maintained, so that muscles have a repetitive pattern of contraction, surrounding fascia changes to support the muscle contraction. It often becomes inflexible so that the muscle is unable to return to a lengthened, resting state. In the case of repetitive motion of the hands and arms, this shortening in the pronators of the forearm leads to a condition where the forearm, even when relaxed, is always in partial pronation. This can easily be seen when a person is lying supine, with arms at the sides, and the forearm rests with the thumb pointing vertically, rather than laterally.

A further problem with this condition is that when the forearm is pronated or partially pronated, the interosseous space is compressed, and in pronation the wrist and finger flexor muscles are also compressed. Since the median nerve lies deep in the tissue of these muscles, this kind of squeezing may create additional pressure on the nerve proximal to the carpal tunnel. As the muscle shortening impedes the ability of the forearm to fully supinate, continual contraction of the interosseous fibers also impedes their ability to fully extend and allow the arm to come into supination. (See the sidebar for working with this problem)

Over-contraction of the opponens and flexor pollicis; contraction of the palmar fascia, particularly at the retinaculum of the wrist; and compression of the carpal joints, particularly the trapezium-scaphoid.
These conditions were most common to workers whose jobs required gripping and manipulating small objects. Again, the repeated contraction of muscles results in an inability for the muscle to return to a full resting state. The appearance of the hand when these conditions are present is that the space across the base of the hand, between the ends of the first and fifth metacarpals, seems narrow -- the hand cannot open wide. The thumb and little finger may look as though they're moving toward each other. Sometimes the palm seems to have a little valley in it at the center of the wrist.

The fascia of these intrinsic muscles of the hands is continuous with the thicker fascia that forms the roof of the carpal tunnel, the retinaculum of the wrist. As with the condition of tension in the bicipital aponeurosis in the forearm, continuous tension in the muscle contributes to inelasticity in the retinaculum, as well as an actual narrowing of the space of the carpal tunnel.

We don't usually consider the mobility of the carpal bones as a factor in repetitive strain, since their mobility is relatively limited. However, the gliding joints between these small bones provide the flexion, extension and rotational movement of the wrist. When movement in the wrist is limited, and muscles and fascia begin to lose their elasticity, this gliding property of the joints can be irrecoverable, as their surfaces jam and fluidity in the joint is reduced. It is also important to remember the bones of the wrist form the "floor" of the carpal tunnel. We generally think of trauma in this area resulting from compression within the tunnel by inflammation of tendons; it is a bit of a leap to consider that restriction in the "roof" of the tunnel, the retinaculum, may also be a factor. It's an even bigger leap to think restriction in the floor might also be a problem, but I believe, at the very least, mobility in the wrist bones helps with the problem of fluid movement in this area, which can help diminish inflammation and edema, precursors to more serious repetitive strain problems.

Tension in thumb extensors, sometimes resulting in pressure on the radial nerve.
This was an unusual condition, only appearing in people whose jobs demanded repetitive use of a wide, rather than a narrow grip. Presenting complaints were numbness in the wrist and hand on the dorsal side. Obviously, this would indicate some difficulty with the radial nerve supply, rather than the median or ulnar nerves. The problem, again, was often in the compression of fascial structures associated with tendons - in this case, the tendons of the extensor pollicis muscles. The dorsal surface of the forearm would often have a peculiar flattening of the tissue approximately two inches above the wrist, where these muscles would be in continuous contraction.

Tension in the neck and shoulders, and anterior movement of the scapula on the ribcage.
Neck and shoulder tension in our society is so common we seldom think of it as anything other than just a condition of living. However, whenever I found another condition of muscle tension that seemed to be a precursor to serious RSI problems, I always found neck and shoulder tension. For the majority of people I worked with, this kind of tension was exacerbated by their working position that demanded the head be inclined forward. While it is possible for typists to alter the position of their keyboard and computer monitors, it was not, at least initially, possible for people who worked with microscopes to do so. Over the course of the years I worked at Starkey, various changes were made in the microscope mounting systems that allowed workers to maintain a more upright posture.

Before these changes were made, working to relieve tension in the neck and shoulder girdle was critical. When you consider the roots of the nerves in the arms and hands are in the lower cervical vertebrae, it's easy to see why it's important to have free movement and release of muscle tension in the neck. I also found it was import-ant to work with restrictions in the shoulder girdle. Continuous forward inclination of the head compresses the upper ribs, often shortening pectoralis minor and encouraging the scapula to slide forward on the ribcage. This increases the chances of compression of the brachial plexus near its origin site.


Conclusion
Management of repetitive stress is critical to all those who use their hands in making a living. A thorough understanding of the anatomy involved in RSI and the factors that contribute to stress are important for the practitioner, both for well-being and therapeutic effectiveness. For the practitioner, working in ways that minimize pressure on vulnerable tissues helps keep the strain to a minimum. Being aware that symptoms of RSI caused by restrictions anywhere in the fascial and neural chains can lead to more thorough treatment.

Siana Goodwin has been a practicing Rolfer since 1980. From 1992-1998, she worked with Starkey Laboratories, Inc., to reduce RSI incidence through Rolfing. Within one year, the company had reduced its workers' compensation costs by 87 percent and currently maintains that reduction. She is a mentor to new Rolfers and teaches workshops in working with RSI and in Rolfing processes. For information about her work, e-mail sbg49@earthlink.net or call 612/722-0049.










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