AJCP / Special Article
Occupational Hazard for Pathologists
Microscope Use and Musculoskeletal Disorders
Evan George, MD
Key Words: Ergonomics; Cumulative trauma disorder; Microscope; Repetitive strain disorder; Work-related musculoskeletal disorder;
Occupational injury
DOI: 10.1309/AJCPUXDS5KJKRFVW
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.
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.
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 Soderberg2 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
© American Society for Clinical Pathology
Am J Clin Pathol 2010;133:543-548
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DOI: 10.1309/AJCPUXDS5KJKRFVW
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CME/SAM
Upon completion of this activity you will be able to:
• become aware of the various musculoskeletal disorders frequently
reported by microscope workers.
• learn which general types of activity have been associated with the
development of work-related cumulative trauma disorders.
• apply ergonomic principles at workstations based on knowledge of the
optimal posture for microscope work.
• proactively reduce the risk of developing a cumulative trauma disorder
by following the recommendations from the Centers for Disease Control
and Prevention.
• promptly recognize symptoms of a work-related cumulative trauma
disorder and seek appropriate medical evaluation.
George / Microscopy and Musculoskeletal Disorders
❚Table 1❚
Survey of Cytotechnologists for Musculoskeletal Pain*
Anatomic Site
Respondents With Symptoms (%)
Any
Headache
Neck
Upper back
Lower back
Elbow
Wrist, left/right
Hands, left/right
85
54
55-60
53
57
35
37/55
38/48
*
From Thompson et al.4
the impetus for intense research into the pathogenesis, treatment, and prevention of work-related MSDs, funded by
government and by private industry.
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
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DOI: 10.1309/AJCPUXDS5KJKRFVW
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
© American Society for Clinical Pathology
AJCP / Special Article
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;
A
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 forwardleaning 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
B
❚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).
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George / Microscopy and Musculoskeletal Disorders
Prevention of CTD: CDC Guidelines
for Microscope Use
❚Image 2❚ Ergonomic microscope with adjustable eyepieces.
The observer can maintain neutral posture of the neck and
upper back.
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.
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) antiinflammatory 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.
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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:
1. 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.
2. 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.
3. Exercise: During breaks and throughout the day, try to
incorporate brief stretching exercises involving the back,
neck, shoulders, arms, wrists, and hands.
4. 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.
5. 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.
© American Society for Clinical Pathology
AJCP / Special Article
Computer Workstation
The CDC also has recommendations to reduce the risk of
CTDs associated with computer use, some of which overlap
with the preceding suggestions18: (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 general19-21 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.
From the Department of Anatomic Pathology, University of
Washington Medical Center, Seattle.
Address reprint requests to Dr George: Dept of Anatomic
Pathology, University of Washington Medical Center, Box
356100, 1959 NE Pacific St, Seattle, WA 98195.
Acknowledgment: I thank Allison Lisle, MD, for serving as a
photographic model to illustrate microscope postures.
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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George / Microscopy and Musculoskeletal Disorders
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© American Society for Clinical Pathology