Background

In April of 1992 1 began working, as a Rolfer, for Starkey Laboratories, Inc. A privately owned company, Starkey is the world’s second largest manufacturer of custom hearing aids. In 1992 they were aggressively addressing problems of high workers’ compensation costs, much of which was due to repetitive stress injuries, such as carpal tunnel syndrome. At Starkey, I do soft-tissue work with people who are exhibiting physical symptoms related to the development of repetitive stress disorders. In addition, I advise people on the positioning of equipment at their workstations to help reduce physical stress, and also do some education for stress reduction, exercise, etc. Employees are not required to work with me; it is strictly voluntary. I believe my work at Starkey offers an example for Rolfers in practicing the profession in alternative settings, and providing a service for organizations as well as individuals.

Some background on Starkey will be useful. The main facility is located in Eden Prairie, a suburb of Minneapolis. It has over 800 employees. Approximately half of them are directly involved with the manufacture of hearing aids; the rest are in administrative and support functions. There are presently 22 Starkey facilities of various size around the world. The Starkey facility in New Jersey has Rolfers Bill Harvey, Linda Grace, and Rebecca Carli-Mills working on-site. These are the only two Starkey facilities that currently provide this service.

Starkey’s workers’ compensation insurance premiums are based on anticipated costs, which are based in part on prior years’ claims. A year of high costs means increased costs over the next few years. Conversely, a reduction in claims means not only an immediate expense reduction but also savings on future insurance premiums. The chart in Figure 1 (shown on following page) shows Starkey’s workers’ comp statistics for the years 1991-94. In 1991 there was approximately $460,000 in costs, representing about 60 claims of repetitive stress injuries. I began working regularly at Starkey in June of 1992, and workers’ comp costs and claims declined. In 1993 and 1994, they continued to decline dramatically, the number of claims being reduced by more than half, and the cost of work comp being reduced to 1 % of the 1991 costs. During this period of cost reduction, I was seeing more people on-site, as shown by the gray bar on the graph. It is of course impossible to directly attribute this reduction in cost to on-site Rolfing. However, within the organization itself, the decrease in workers’ comp costs is attributed to Rolfing.

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The diagram above compares the number of worker’s compensation claims and costs at Starkey Laboratories Eden Prairie facility for four years. “Number of employees Rolfed” was calculated on a per session basis; one employee seen 5 times counts as five people. Over the period shown, work-comp claims decreased from 60 to less than 20; and costs dropped from $450,000 to $4,000.

I should add here that I am not doing a Rolfing series or working with the entire body. I only address fascial conditions relating to stress in hands, arms, and necks.

Conditions of Repetitive Stress in an Industrial Setting

Helen James’ article in carpal tunnel syndrome has detailed the anatomy and sources of stress in the neurology of the hand. This article will show how those stresses can be identified in the actual working conditions of hearing aid manufacture. While this is a very specific situation, I believe it can serve as an ex. ample for addressing any workplace.

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Some understanding of the process of making custom hearing aids will help in observing the conditions of repetitive stress syndrome as seen at Starkey. The company specializes in making hearing aids that fit within the ear, either in the outer part of the ear or in the canal. Figure 2 (above) shows these different types of hearing aids. The extremely small size is evident. The components of hearing aids include microphone, receiver, amplifier, and battery. All electronic components are wired into circuit boards, shown underneath each aid. During the wiring process, the circuit board is embedded in a plastic plate (Figure 3 below) that will later be trimmed to fit the custom shell of the hearing aid.

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Because the components of the aids are so small, a microscope is used for the wiring process. Figure 4 (pictured below) shows a wirer at work. It is not so obvious when first looking at it, but the use of the microscope places a peculiar stress on the neck. The neck must be flexed in order to bring the head forward, but must also be extended slightly (from about C4 and C5) in order to see into the eyepiece. This position is obviously a source of muscle strain, and possibly of the “double crush” syndrome mentioned in Helen James’ paper.

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In the process of wiring (Figure 5 below), the wirer holds the component wire in place with tweezers with one hand, while using a soldering iron to connect other wires and components. The continual maintenance of a tight grip on small surfaces is a primary source of muscle stress and consequent circulation restriction and nerve irritation.

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Such stress factors are also present in other jobs connected with hearing aid manufacture. Figures 6, 7, and 8 (below) show the processes of cutting, venting, and surfacing, respectively. In cutting, the plate holding the circuit board is trimmed to fit the shell of the hearing aid. An electrically powered, rotating cutting blade is used for this. In venting, a drill is used to shape the hearing aid shell to accommodate components and provide ventilation. In surfacing, the end of the case is being sanded to fit snugly against the plate. In all of these jobs, the extremely tight pinching movement of the hands is evident. Problems caused by maintaining this tight grip can be exacerbated by the vibration of the tools used. Also, most workers with jobs of this kind have a tendency to bend close to their work. They are unsupported in sitting, even when they use ergonomically designed chairs. This kind of posture also promotes the possibility of nerve stress at the anterior neck.

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Another exacerbating factor is immobility. Sustained positions restrict blood supply to the muscles that maintain that position, which can result in measurable loss of the muscle’s capability. Blood supply to the nerves is also diminished, leading to lessening of nerve efficiency and ultimately nerve damage. And, obviously, the positions which are maintained for long periods of time can also result in nerve compression.

Some Factors in Working With Repetitive Stress Syndrome

Before the completely debilitating symptoms of carpal tunnel syndrome appear, there are usually symptoms of tingling and numbness in the hands or fingers, or a weakening of grip strength. I believe if an intervention (soft tissue work being ideal for this) is made at this point, the continuing irritation on muscle and nerve is reduced, and full-blown carpal tunnel syndrome can be avoided. In this section, I’ll share with you what I’ve observed about conditions that seem to precede carpal tunnel syndrome. Reference to an anatomy atlas, detailing the musculature of the forearm and hand, and the pathways of the median, ulnar, and radial nerves, will be useful for this.

The first factor I’ve found is that stress will often appear in the thumbs. In the maintenance of a tight grip, there is continual contraction of the thenar and hypothenar muscles. Often the first complaints of repetitive stress that I hear are of pain in the carpal-metacarpal joint of the thumb, soreness or pain in the thumb extensor tendons, and cramping or tingling in the flexors and opponents of the thumb.

The possible importance of these symptoms in the thumbs can be seen by looking at the ligaments of the abductor and the opponents group. The fasciae of these ligaments are virtually continuous with the carpal retinacula. Repeated contraction or shortening of these muscles will also affect the resiliency and perhaps length of the retinacula. In my experience, the whole carpal ligament area appears to shorten, so you see a bunched look of the tissues at the carpal ligament. The hand appears narrow just distal to the wrist.

When this shortening, or lessening of resiliency, at the carpal ligament occurs, it also seems to involve the carpals themselves. The carpal ligament attaches to the hamate and the trapezium, which articulate with the metacarpals of the little finger and thumb, respectively. Shortening of the muscle attachment and the connective tissues between the hamate and trapezium not only decreases the length of the proximal carpal ligament, it can cause a slight rotation in the wrist bones. Helen James’ article pointed out that there is a greater degree of play in the proximal ligament of the carpal tunnel, but also that there is less space in the carpal tunnel at this point. The rotation of the carpals can alter the space of the carpal tunnel from the bottom, as well as putting pressure on it from the top. Even though the change may be very small, I believe it can significantly alter the pressure within the carpal tunnel.

My primary approach to these symptoms is to lengthen the area of the carpal ligaments. What I look and feel for is ability of the muscles involved in opposition to extend. I also check for the feeling of the carpal bones being in place and appropriately mobile. The relationships of the thenar metacarpal to trapezium and scaphoid, and the capitate to the scaphoid and lunate seem especially important in this.

Bearing in mind the possibility of “double crush”, I also insure that the finger flexor and thenar extensor compartments in the forearm have free movement. Some specific sites often need attention. One is the area of the biceps tendon attachment. Some anatomy texts show the biceps tendon as having two branches, spreading out into the flexor fascia as well as attaching to the radius. In addition, the biceps tendon is superficial to the brachialis tendon on the inside of the elbow, and the brachialis, in its excursion to its ulnar attachment, makes part of the bed of the median nerve. Tension in the biceps seems to shorten the whole connective tissue web of this area.

Supinator and pronator muscles are also key. Pronator teres as a structure of the anterior elbow can exert pressure on the medial nerve bed. In addition, pronator teres and supinator can also become inelastic due to lack of movement, and fixed positions are a given in many manufacturing jobs. I find it important in distinguishing the function of the wrist, finger, and thumb muscles, to also distinguish the movement of supinator and pronator. My approach to this is to ask for finger flexion, and gentle pronation and supination of the arm, while working.

Often symptoms of pain, tingling, or numbness in the extremities are due to pressure at or near the root of the brachial plexus. Stresses in the neck, and at ribs one and two, are often part of this. It is evident from the pictures of the workers using the microscope, that the peculiar fix of the neck-part flexed and part hyper-extended-exerts an unusual stress, much of it in the scalenes. There is usually compression in this area, with the possibility of rib #2 crowding up against rib #1. When working with symptoms of stress in the hand, I will usually also find muscular stress in the neck, and neck pain and tension often precede symptoms in the hand.

Although the fashionable concern with repetitive stress injuries is with carpal tunnel syndrome, some types of work stress other nerves as well as the median nerve. Resting the forearms on hard or edged surfaces can put pressure on the radial nerve and lead to sensory problems or problems with extending the hand. Jobs that require tight grip such as are illustrated here will often lead to stress on the ulnar nerve, which can produce discomfort, both sensory and motor, before the median nerve may be affected.

Working on-site provides some experience for a Rolfer that isn’t always available in a private practice. You are able to observe conditions that lead to the development of repetitive stress problems, and have the satisfaction of working with them before they become crippling. You are also able to work in a direct way with people’s work habits. On-site coaching in body use, supported sitting, etc. has more immediacy and impact for the client. Often modifications of the physical environment reduce continued physical or repetitive stress. The combination of workplace modification and soft-tissue work can be highly effective in reducing work-related stress disorders.

Bibliography for James and Goodwin Articles

Batement, James E., Trauma to Nerves in Limbs, W.B.Saunders Co., Philadelphia, 1962.

Butler, David S., Mobilization of the Nervous System, Churchill Livingstone, New York, 1991.

Cailliet, Rene, Hand Pain and Impairment ED3, F.A. Davis Co., Philadelphia, 1962.

Chusid, Joseph G., 15th Ed. Correlative Neuroanatomy and Functional Neurology, Lange Medical Publications, Los Altos, CA, 1973.

Guyton, Arthur C., Textboook of Medical Physiology-6th Ed., W.B.Saunders Co Philadelphia, 1981.

Haymaker, Webb and Woodhall, Barnes, Peripheral Nerve Injuries, W.B.Saunders Co Philadelphia, 1953.

Hollinghead, Henry W., Functional Anatomy of the Limbs and Back, W.B.Saunders Co Philadelphia, 1991.

Kelly, Douglas. E., Wood, Richard L., Enders, Allen C., Bailey?s Textbook of Microscopic Anatomy 18th Ed., Williams and Wilkins, Baltimore, 1984.

Liveson, Jay A., and Spielholz, Neil, Peripheral Neurology ? Case Studies in Electacodiagnosis, F.A.Davis Co., Philadelphia, 1979.

McNew, Kristen, artist

Sunderland, Sydney, Nerves and Nerve Injuries, E.&S.Trunstone LTD, Edinburgh and London, 1968.

Warwick, Roger and Williams, peter L., Group Anatomy 35th British Edition, W.B.Saunders Co Philadelphia, 1973.