Medical Effect of Continuous Use of a Microscope
Abstract
The association of prolonged microscope use with the development of chronic pain syndromes has been recognized for nearly 3 decades; yet most pathologists are not well-informed about this hazard until after they develop a problem. The purpose of this article is to make pathologists aware of this risk, discuss current pathogenetic models, and encourage them to proactively integrate prevention strategies into their daily lives.
Although increased neck and back pain have been anecdotally reported by biomedical microscopists for more than a century, 1 no systematic survey of microscopists was published until that of Soderberg 2 in 1980. Subsequently, several large surveys have documented a high prevalence of musculoskeletal disorders (MSDs) among microscopists, 2 of which were based on surveys of cytotechnologists. 3,4 These workers reported a high prevalence of pain of the neck, upper back, lower back, shoulder, and upper extremities Table 1.
A more recent European survey also documented a high prevalence of musculoskeletal pain among microscope workers. 5 These investigators attempted to identify risk factors associated with the development of symptoms. Hours of microscope work, duration of work without breaks, fast work pace, and poor workstation ergonomic conditions were associated with symptoms.
Despite the widespread availability of ergonomically improved microscopes, there continues to be a high incidence of musculoskeletal pain among practicing pathologists. Two recent trends have likely increased the amount of musculoskeletal stress: (1) the ever-increasing quantity of microscopic specimen examinations required to maintain income levels in an environment of decreasing reimbursement and (2) widespread integration of computers into routine pathology practice and daily life. Computer use alone has been strongly associated with MSDs. For pathologists, simultaneous use of microscopes and computers has become routine in daily specimen examination and reporting. Indirectly, however, computer-related MSDs have been helpful to microscope workers in that they have provided the impetus for intense research into the pathogenesis, treatment, and prevention of work-related MSDs, funded by government and by private industry.
Table 1
Survey of Cytotechnologists for Musculoskeletal Pain*
Table 1
Survey of Cytotechnologists for Musculoskeletal Pain*
Cumulative Trauma Disorders: General
Several names have been used for these MSDs, including cumulative trauma disorder (CTD), overuse syndrome, and repetitive stress injury or repetitive strain injury. Activities leading to these disorders feature one or more of the following: excessive force, repetitive movement, awkward posture or prolonged static posture, and vibration. From a medical perspective, the pathophysiology of CTDs has not been fully elucidated. Some skeptics have challenged their classification as injury or trauma, instead attributing symptoms to psychosocial and economic factors. Nevertheless, many of us who have been directly affected by one or more of these disorders think otherwise: the affected pathologists with whom I have worked have been emotionally stable, dedicated physicians with no secondary gain associated with their symptoms. To prevent these work-related MSDs, pathologists need to have greater awareness and better understanding of the risk factors.
Three general (not mutually exclusive) pathophysiologic mechanisms have been postulated as explanations for the development of CTDs: (1) repetitive mechanical irritation, (2) microischemia, and (3) accumulation of metabolic products that promote inflammation or interfere with neuromuscular function. 6–9 Most proposed mechanisms feature a persistent and recurrent cycle of inflammation, tissue injury, and fibrosis leading to episodic pain and to dysfunction of muscles, ligaments, and fascia. The third category also includes a growing body of evidence that increased levels of endogenous substances may interfere with neuromuscular function, activate local pain receptors, or cause hyperexcitability of central nervous system pain responses. 9–12
The following discussion will concentrate on neck and upper back pain; this is the area most intensely affected by microscope use in my personal experience and among pathologists with whom I have worked. The reader should be aware, however, that microscope use has also been associated with MSDs involving the shoulders, arms, wrists, hands, and lower back.
The Neck: Structure and Function
As with other structures, the complexity of normal neck anatomy and physiology is not appreciated until a related medical disorder develops. The functions of the neck are to hold the head upright, maintain normal spinal curvature for weight-centered balance and posture, and move the head in various planes without injury to the spinal cord or nerves. Thus, multiple structures are necessary to provide stability, mobility, and protection from external forces including the following: (1) at least 12 sets of paired muscles, 7 each attached to tendons and fascia (sternocleidomastoid, trapezius, rhomboids, levator scapulae, scalenes, and others); (2) articular structures attached to each vertebral body to facilitate mobility between contiguous vertebrae (the "facet" or "zygapophyseal" joints); (3) ligaments, including small intervertebral ligaments and large ligaments such as the anterior and posterior longitudinal ligaments that are necessary for spinal stability, 8 and they form the "capsules" surrounding and protecting the facet joints; (4) intervertebral disks, which protect the spine from external forces; and (5) vertebral bones that surround and protect the spinal cord.
Without our conscious awareness, our neck holds a "14-lb bowling ball" (the typical weight of an adult human head) upright throughout most of the day, excluding sleep. This is quite a feat! What if you were given two 7-pound dumbbells in the morning and asked to hold them upright at equal height with your biceps in a flexed position all day? Your arms would probably become sore and fatigued.
The Neck: Evidence and Possible Mechanisms for Work-Related Cumulative Trauma
In 1997, the National Institute for Occupational Safety and Health published a critical synopsis of evidence-based medical investigations into the associations between work activities and the development of MSDs. 13 There was strong evidence that high levels of static contraction, prolonged static loads, and awkward postures involving the neck and shoulder muscles were associated with an increased risk for MSDs. At least 12 high-quality studies linking static postures/static loads with "tension-neck syndrome" were cited (odds ratios were greater than 3.0 and statistically significant). There was also some evidence that highly repetitive work involving continuous movement of the arm or hand generates loads on the neck and shoulders and is also associated with the development of MSDs (9 studies with odds ratios greater than 3.0 and statistically significant).
Emphasis must be placed on the term static because most of us do not intuitively associate sitting in a chair for prolonged intervals with tissue injury. This was a surprise to me! Some authors of the cited studies postulated explanations for the association between static loading and CTDs: these included local ischemic injury, local disturbance of energy metabolites, and aberrant muscle contraction-rest cycles in small muscle fibers.
The ischemic or toxic metabolite hypotheses are plausible explanations for the association of sustained postures with the development of MSDs. The neck and back muscles truly are working when we are sitting down viewing slides at the microscope or staring at a computer; this has been confirmed by surface electromyography. 7 In the sitting position, blood flow to these muscles may be suboptimal due to gravitational forces, lack of movement, and increased tension. Moreover, by using surface electromyography to measure muscle activity in the seated posture, some investigators have observed that neck muscles generate more electrical activity (ie, work harder) during cognitive tasks compared with noncognitive tasks. 14
The role of awkward postures also cannot be overemphasized. Until recently, virtually all light microscopes had eyepieces at fixed, acute angles relative to the microscope body. Most users have had to flex the neck and upper back to view through the eyepieces Image 1. Microscopes with tilting and telescoping eyepieces are now commercially available through major manufacturers of medical microscopes; however, because of their higher purchase price, they have not entirely replaced the traditional fixed-angle microscopes. Thus, technologists and pathology residents frequently are still using the traditional type of microscope, which predisposes to the development of MSDs. Also, microscopes with traditional fixed-angle eyepieces remain commonplace in frozen section suites and multiheaded teaching microscopes.
In simple terms, when the neck is in a flexed posture for prolonged intervals, the extensor muscles, tendons, and ligaments are stretched, leading to laxity and weakness. After years of this practice, microscopists tend to develop forward-leaning posture and extensor muscle dysfunction accompanied by symptoms of pain, stiffness, and muscle fatigue.
Therefore, the neck should be in neutral posture during microscope use (ie, looking straight ahead parallel to the floor, similar to looking into a periscope) Image 2. Even with the benefit of a microscope with tilting eyepieces, there may be a tendency for the viewer to lean forward flexing the neck, particularly if the microscope head is too low or the microscope is positioned too far from the edge of the table. In addition to microscope use, pathologists are exposed to numerous other activities that promote forward-leaning posture, such as reading, writing, viewing a computer screen, cutting frozen sections, and dissecting specimens, in addition to activities such as driving a car and sleeping with a thick pillow in everyday life.
It is also important to maintain neutral posture when viewing a computer screen for extended periods. For people who wear corrective lenses, bifocal or progressive lens spectacles can promote repeated extension of the neck to read from a computer screen. Because pathologists frequently combine microscope and computer work, this can pose an additional musculoskeletal hazard. 15,16 In general, single lens spectacles with appropriate correction for the distance between the viewer and computer screen are preferable in these contexts. Progressive lens spectacles can be worn for other daily activities.
Image 1
Traditional medical microscope and postural strain. The fixed, acute angle of the eyepieces promotes excessive flexion of the neck (A) or upper back (B).
Image 2
Ergonomic microscope with adjustable eyepieces. The observer can maintain neutral posture of the neck and upper back.
Treatment
One should seek evaluation and treatment from the onset of work-related musculoskeletal pain, even if symptoms are mild. Initially, it may not be obvious that the pain is related to work activities, so one must maintain a high index of suspicion. A physical medicine specialist is usually the most qualified physician for initial diagnosis and management of these disorders. After initial evaluation and diagnosis, management will likely involve the following: (1) worksite evaluation by a health care provider with expertise in ergonomics, often an occupational therapist or a physical therapist; (2) anti-inflammatory medication; (3) physical therapy to improve posture, flexibility, and muscle endurance in the affected anatomic region (initially requires supervised stretching and strengthening exercises followed by independent home exercise); (4) interventions to mobilize affected structures such as massage therapy for myofascial release; and (5) continued care oversight by a physical medicine physician specialist. It is important to realize that symptoms may not completely resolve, even with optimal treatment. Thus, prevention is the best approach for people at risk.
Prevention of CTD: CDC Guidelines for Microscope Use
The Centers for Disease Control and Prevention (CDC) has published suggestions for microscopists to reduce their risk of developing a CTD. 17 I have modified them slightly, as follows:
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Workstation design: The dimensions of its potential users need to be considered when setting up a microscope workstation. Because laboratory personnel come in many different shapes and sizes, workstations used by different people should be made as adjustable as possible. Ideally, microscopists should be able to adjust the height of the chair, work surface, and microscope.
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Nothing in excess: Rest! (a) Do not use a microscope for more than 5 hours per day. (This interval is the recommendation of the CDC and was not modified.) The number may be arbitrary. However, the message is clear: greater exposure duration to risk-associated activities will increase the probability of developing a CTD. (b) Take frequent short breaks from microscopy work. (c) Vary your activities during the work day to avoid long, uninterrupted periods of microscope work.
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Exercise: During breaks and throughout the day, try to incorporate brief stretching exercises involving the back, neck, shoulders, arms, wrists, and hands.
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Promote neutral spinal posture (avoid forward leaning): The following adjustments can help position the operator in a more upright posture, reducing the tendency for rounding of the shoulders and neck. (a) Try pulling the microscope toward the edge of the work surface to position the operator in a more upright posture. (b) Make sure there is adequate room under the work surface so you can pull the chair up to the microscope eyepieces. (c) Consider using a cutout work table. This puts you close to the scope and gives an area for supporting forearms. (d) If feasible, use a microscope with tilting and telescoping eyepieces. (e) Alternatively, try elevating the microscope or placing it at an angle so you can look directly into the eyepiece.
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Support: Remember that muscles are working and become fatigued even when we are still. (a) Use an ergonomically designed chair that provides adequate upper and lower back support and has an adjustable seat height, adjustable seat angle, and adjustable arm rests. (b) Arm support is essential; however, the arm rests on a chair may prevent sitting close to the table. If so, detach the arm rests from the chair and use table-mounted arm rests to support the forearms. (c) If your feet do not rest squarely on the floor, use a footrest; this will decrease the load on the arms and shoulders.
Computer Workstation
The CDC also has recommendations to reduce the risk of CTDs associated with computer use, some of which overlap with the preceding suggestions 18: (1) Promote upright posture and support with a fully adjustable ergonomically designed chair. (2) Ensure proper keyboard height so that the arms are positioned roughly parallel to the floor. If necessary, install adjustable keyboard platforms under the table. (3) Place the mouse beside the keyboard and at the same height to prevent reaching. (4) Provide for a choice of keyboards and mouse or other input devices for people who have existing musculoskeletal problems. (5) Place monitors so the user's viewing distance is between 18 and 30 inches. (6) Place monitors so the top of the screen is approximately at eye level to allow the eyes to naturally gravitate toward the center of the screen. (7) Use a document holder placed adjacent to and at the same height as the computer screen. (8) Provide footrests, where possible, so people can change leg positions throughout the day. (9) Encourage minibreaks of 3 to 5 minutes for every 20 to 30 minutes of keyboarding or mouse work. These breaks can be spent doing light hand exercises or stretches.
Additional Suggestions
The following are miscellaneous suggestions, most of which have been made by my care providers or encountered by me in medical publications. (1) Be proactive about obtaining an ergonomic evaluation. Do not wait until you have symptoms before requesting an evaluation of your workstation. Most large medical institutions have personnel with expertise in ergonomics available to help employees. In addition to evaluating the equipment and layout of your workstation, be sure that you are also observed while working at the microscope and at the computer so that awkward postures can be corrected and unnecessary repetitive movements reduced. (2) Ask a colleague to observe your posture at your workstation periodically to see if you are maintaining the neutral cervical spine position. (3) Develop a habit of observing and correcting your general posture in the mirror regularly, which can be done concurrently with some stretching and strengthening exercises. (4) Try varying your posture during the sustained work activities to distribute musculoskeletal stress more evenly along the spine. For example, because much time is spent in a seated position for sign-out of microscopic slides, I find it helpful to do some of my computer work in a standing position. Motorized, pushbutton, height-adjustable tables are now commercially available at reasonable costs. At my computers, I have a mouse for each hand. When one side starts to feel sore or fatigued, I switch to the other. (5) If you wear corrective lenses, avoid the use of bifocal or progressive lens spectacles when working at the computer screen for extended periods. Instead, once your workstation has been ergonomically optimized, measure the distance from your typical seated position to the computer screen and ask your eye care professional to prescribe a set of single lens spectacles appropriate for that distance. (6) Be cognizant of other activities that may be sources of musculoskeletal stress, particularly activities that predispose to neck flexion. For example, if you do a lot of reading, consider using a bookstand to hold books in an upright position. (7) Consider taking a day off in the middle of the week to give the muscles a rest. (8) Try to offset the negative effects of prolonged sedentary work activity with regular physical activity outside of work.
Additional Resources
There are multiple Internet-based resources with information on ergonomics in general 19–21 and on ergonomics specific to medical laboratory personnel. 17,22,23 Descriptions of helpful stretching and strengthening exercises are available at multiple Web sites, 24,25 in textbooks of physical medicine, and in specialized publications. 26 Commercial sources of ergonomic products can be found on the CDC Web site and at the sites of microscope manufacturers and office product vendors. 27
Summary
Practicing pathologists are at high risk for the development of MSDs of the neck, upper back, lower back, shoulders, and upper extremities related to cumulative trauma. Current treatments often alleviate pain, but symptoms may persist indefinitely in a significant percentage of affected people. Thus, pathologists are strongly encouraged to adopt preventive measures before symptoms develop and to seek prompt medical evaluation if they experience symptoms.
I thank Allison Lisle, MD, for serving as a photographic model to illustrate microscope postures.
Upon completion of this activity you will be able to:
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become aware of the various musculoskeletal disorders frequently reported by microscope workers.
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learn which general types of activity have been associated with the development of work-related cumulative trauma disorders.
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apply ergonomic principles at workstations based on knowledge of the optimal posture for microscope work.
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proactively reduce the risk of developing a cumulative trauma disorder by following the recommendations from the Centers for Disease Control and Prevention.
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promptly recognize symptoms of a work-related cumulative trauma disorder and seek appropriate medical evaluation.
The ASCP is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The ASCP designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit™ per article. This activity qualifies as an American Board of Pathology Maintenance of Certification Part II Self-Assessment Module.
The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose.
Questions appear on p 669. Exam is located at www.ascp.org/ajcpcme.
Note: The information in this article is largely based on my personal experience, discussions with pathologist colleagues, reading of medical articles, Internet searches, and advice from rehabilitation medicine physicians, physical therapists, and occupational therapists. It should not be interpreted as a critical scientific literature evaluation or used as a substitute for the expertise of physical medicine health care providers. If the reader is experiencing pain related to work or of unclear cause, formal evaluation by a physical medicine physician and appropriate allied health care providers is recommended.
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© American Society for Clinical Pathology
© American Society for Clinical Pathology
Source: https://academic.oup.com/ajcp/article/133/4/543/1760498
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