Epidemiology of Neck Pain
R. Gore, MD,
Medical College of Wisconsin, Milwaukee, Wis.
is a common problem in our society and, at any given time, affects about 10%
of the general population. The sources of pain are caused by conditions that
compress, destroy, or irritate pain-sensitive structures such as the annulus
fibrosus, posterior longitudinal ligament, and the capsule of the
zygapophyseal joints. Involvement of the cervical nerve roots usually results
in pain and neurologic findings in the distribution of the nerve. Referred
pain from visceral disease may cause neck pain and may also be confused with
primary shoulder disease and peripheral nerve entrapments. Common conditions
thought to cause neck pain are degenerative disc disease, with or without disc
herniation, and degenerative arthritis of the zygapophyseal joints. Aside from
patients with disc herniations demonstrated on imaging studies and pain in a
specific nerve root distribution, the relationship with degenerative changes
is not always clear. This is because degenerative conditions are common with
aging and many times are incidental findings in asymptomatic people. Specific
conditions that have been studied but also are not well understood are
post-traumatic neck pain syndrome, commonly known as whiplash injuries, and
pain following repetitive activities in an occupational setting. Although
causes of neck pain are not well understood, outcome studies have shown that
it frequently is not a self-limiting condition and can be a long-term problem.
[© 1998 Medscape, Inc.]
is the branch of medical science that studies the causes, incidence,
prevalence, and control of a disease in a defined population. Although there
are numerous epidemiologic studies of low-back pain, relatively few
investigations of neck pain have been conducted. There are several reasons for
this, the most important being that neck pain is not as common as low-back
pain and, when present, is not as disabling; therefore, it doesn't have the
same economic impact on society as does low-back pain.
Neck pain is a symptom of a disease process. Knowing the etiology of
neck pain aids in understanding its epidemiology.
of Neck Pain
human neck is a complex structure that contains the extension of a number of
vital visceral structures, including the trachea, esophagus, and the carotid
and vertebral arteries, and a musculoskeletal system that provides for support
and motion of the head. The cervical spine itself is a series of seven
separate bone elements, all with intricate articulations and an elaborate
system of ligaments and associated muscles. The first and second cervical
vertebrae are different in size and shape from each other and the remaining
five vertebrae. However, all of the segments have true synovial joints. The
anterior articulations of the vertebrae below C2 occur via intervertebral
discs. Both the anterior and posterior joints are surrounded by a fibrous
capsule and supported by ligaments and muscles. These joints both allow and
limit neck motion. The capsule, ligament, and muscles all contain an abundance
of free nerve endings which are capable of transmitting pain impulses.
Irritation or damage to these structures causes primary neck pain.
cervical vertebrae also protect and allow passage of the spinal cord and
cervical nerve roots. Pathologic processes such as compression, especially of
the nerve roots, are a frequent source of neck pain and referred pain from the
neck. Cervical nerves are both sensory and motor so that damage, in addition
to pain, may cause numbness, tingling, muscle weakness, and reflex deficits in
a specific location. Signs and symptoms along the distribution of a cervical
nerve root are called cervical radiculopathy.
cervical nerve roots C5, C6, and C7 are the most commonly involved and result
in characteristic signs and symptoms in the upper extremities. Because the
distal-most innervation of C4 is to the top of the shoulder, compression of
the C4 nerve root does not produce symptoms below the level of the shoulder,
and usually there is no demonstrable muscle weakness or any reflex
abnormalities. Damage or irritation of C1, C2, and C3 does not result in
reflex or motor deficits but can result in pain in the back of the neck
extending along the back of the head. Pain from neck sources other than
cervical nerve roots does not result in sensory, motor, or reflex deficits and
the pain patterns are not as well defined. Pain reproduction studies have
investigated patients with neck pain but without evidence of specific nerve
root involvement. Discography and zygapophyseal joint injections
were used, indicating that there are a variety of etiologies for neck pain.
Other possible sources of neck pain, whose importance has not been
established, are the cervical sympathetic nerves and the innervation present
in the anterior surface of the dura.
of Neck Pain
originating in and confined to the neck may arise from infections, tumors, and
degenerative changes of the zygapophyseal joints and intervertebral discs.
Cervical radicular pain is pain in the distribution of a cervical nerve root.
This can be caused by any process that compresses or irritates the nerve, the
most common being herniated intervertebral discs (Figure 1a,b) and osteophytes
which narrow the neuroforamen (Figure 2a,b,c). Disc protrusion and osteophytes
can also narrow the spinal canal, causing pressure on the cervical cord and
resulting in a myelopathy (Figure 3).
neck pain is generated by disease in an anatomic structure other than the
neck. Examples of this are visceral diseases such as angina, apical lung
tumors, and subdiaphragmatic irritation as in a subdiaphragmatic abscess. The
most common conditions that may be confused with neck problems are intrinsic
shoulder diseases such as impingement, rotator cuff tears, and adhesive
capsulitis. Peripheral nerve entrapment occurring in thoracic outlet syndrome,
ulnar cubital tunnel syndrome, and carpal tunnel syndrome can simulate
cervical nerve root compression. Systemic diseases such as rheumatoid
arthritis, spondyloarthropathies, fibromyalgia, and herpes zoster may also
cause neck pain. However, in these conditions it is unusual for the only
symptom to be in the neck.
and Prevalence of Neck Pain
pain has most frequently been studied in five different populations
is the number of new cases of a disease which occur during a specified period
of time, whereas prevalence is the number of cases present at any one time.
Most reports in the medical literature are crude prevalence studies. Since
neck pain has many causes, and a number of factors such as age, sex,
occupation, and cigarette smoking effect its occurrence,
it is difficult to compare the results obtained from research done on
differing study populations. In addition, most reports are based on
questionnaires, so the cause of the pain cannot be validated; also, neck,
shoulder, and upper-extremity pain are frequently considered together.
with the limitations mentioned above, some information -- mostly from
Scandinavian countries -- is available. Neck pain occurs half as often as
and is slightly more common in women. In Norway, Bovim and colleagues,
in a random sample of 10,000 persons ages 18-67 years, found a prevalence of
13.8%. In a similar study in Finland, Makela and associates
discovered neck pain in 9.5% of males and 13.5% of females. The United States'
National Center for Health Statistics reported 7.0% of men and 9.4% of women
had neck pain in the period between 1976-1980. In
addition to neck pain being more common in women, Makela
also found that older patients, those involved in both mentally and physically
stressful jobs, and current smokers were more likely to have neck pain.
most common post-traumatic neck pain syndrome is a
whiplash injury and follows an automobile accident. The term was first
used by Crowe
in 1928 in an unpublished report, then in an article by Davis
in 1945, and later by Gay and Abbott in
1953. The original descriptions were of a mechanism of injury rather than a
disease process. Although many now object to its use, the term
"whiplash" is routinely used by laymen, lawyers, and medical
professionals in reference to a patient with neck pain after an automobile
accident in which a more specific diagnosis cannot be made.
most frequent scenario is a patient whose vehicle is struck from behind
causing a hyperextension motion of the neck. The combination of seat belts and
properly adjusted head restraints reduces the likelihood of neck injuries.
Grauer and colleagues have
shown with cadaver studies that in a simulated whiplash injury the neck forms
an S-shaped curve with initial hyperextension of the lower cervical spine and
upper-level flexion, followed by extension of the entire cervical spine. It
would be expected that if physiologic limits of motion are exceeded, than
injury would occur. This physiologic limit of motion was reached in the lower
cervical spine in their studies.
injuries of the neck can damage a number of structures, including the anterior
muscles and ligaments, the disc, and zygapophyseal joints. These injuries have
been demonstrated on cadavers and experimental animals and found in human
autopsy studies of victims of motor vehicle accidents.
Jonsson and coworkers
reported on 50 consecutive patients with whiplash-type cervical spine
distortions in automobile accidents. At 6 weeks, 24 had persistent neck pain
and underwent MRI imaging. Of these, 8 were found to have large cervical disc
protrusions and had surgery. Two patients had posterior fusions for
instability based on lateral flexion and extension films. This
report is in contrast to our own experience and that of others' where, despite
careful evaluation of whiplash patients, conclusive objective pathology is
studied 201 patients with neck pain following automobile accidents. The
patients were randomly divided into two treatment groups. In one group,
immobilization by means of a cervical collar and sick leave from work was
provided. In the other, no immobilization was used, no sick leave was given,
and the patients were instructed to act as usual. At 6 months, the
"act-as-usual" group showed more overall progress, as measured by
subjective symptoms ratings. The researchers found, however, that 10% of this
group still had severe symptoms at 6 months, which
emphasizes that neck pain following an automobile accident in many patients is
not a self-limited condition.
symptom complex most frequently seen is neck pain that may not be present
immediately after the accident but begins in most patients within 24 hours.
Other frequent complaints are headache, dizziness, paresthesia, and cognitive
somatic and psychological sequelae.
unrelated constellation of symptoms without objective evidence of structural
injury has led to speculation that the condition is an emotional rather than a
physical problem. Since the neck pain patient's vehicle has been struck from
behind, causation and therefore liability usually rest with the other driver.
Our current tort system favors documentation which encourages frequent
physician visits, exaggeration of complaints, expensive testing, and extensive
symptomatic treatment, most of which have no proven value in altering the
natural history of the patient's symptoms.
neck pain can be divided into two categories -- those patients who have had
specific injuries and those in whom the onset of neck pain seems to be related
to normal work activity.
injuries that may occur in the workplace include motor vehicle accidents,
falling from a height, and being struck on the head. In these instances,
causation is not hard to determine; neck pain that begins during normal work
activities, however, is more difficult to assess.
in occupations which require repetitive use of the upper extremities such as
machine operators, carpenters, and office workers are more likely to have neck
If work activity is truly the cause the of the patient's complaints then a
strong relationship with the activity and the onset and persistence of the
symptoms should be evident. For instance, it must be established that the
symptoms began after performing the activity and the complaints improve or
completely subside if that activity is eliminated. Usually the distinction
between work causation and other factors is not clear because preexisting
disease and activities that are not involved with work cloud the picture. In
addition, there is no conclusive evidence in the medical literature that
overuse results in structural damage. There is, however, a segment of the
population with permanent symptoms after a period of overactivity at a
specific task. In these situations, evaluation and treatment proceeds as with
any other group of patients but causation usually cannot be established.
Intervertebral Cervical Discs
contrast to studies of patients with neck pain as a syndrome, a herniated
cervical disc is a specific diagnosis. The only published study that provides
an incidence rate was done by Kondo and colleagues.
They analyzed residents of Rochester, Minn, from 1950 to 1974 and found an
annual herniated disc incidence of 5.5/100,000 people. The most frequent level
involved was C5-6, followed by C4-5 and C6-7. In reviews of surgically-treated
patients, these are also the most frequent levels involved.
and associates reported
on 88 people with cervical disc protrusions living in New Haven and Hartford,
Conn. Forty were surgically treated after the diagnosis of herniated cervical
disc was made. Based on their clinical appearance, 20 were listed as probable
and 28 as possible disc protrusions. Fifty-two patients were men and 36 were
women, and most patients were in their 40s and 50s. The researchers compared
cervical disc protrusion patients with age- and sex-matched controls. A strong
association was found between protrusion and recurrent lifting of heavy
objects on the job, cigarette smoking, and frequent diving from a board.
Driving vibrating equipment and time spent in motor vehicles were weakly
associated. Frequent twisting of the neck on the job and sitting on the job
were not associated with the clinical diagnosis of herniated disc.
association of lifting heavy objects and driving vibrating equipment with
prolapsed disc is not surprising, but the relationship with smoking is not as
easily explained. Cigarette smoking has been implicated in impeding bone
metabolism and in interfering with fracture repair, in nonunions in fractures,
in arthrodesing procedures, and in increasing the rate of postoperative wound
A number of studies have identified smoking as a risk factor for low-back
pain, and although several explanations have been proposed, the mechanism has
not been elucidated.
changes of the intervertebral discs cause disc-space narrowing, osteophyte
formation, and sclerosis of the vertebral body end plates (Figure 4). These
changes are easily seen on lateral roentgenograms but are the response of the
vertebrae to disc degeneration and so appear after the process is well
developed. Therefore, any study based on plain roentgenograms underestimates
the prevalence of disc degeneration. Degenerative changes in the zygapophyseal
joints include joint-space narrowing, sclerosis, and osteophyte formation; but
the changes are not as easily seen or quantified on plain roentgenograms
(Figure 5). The joints are paired and located behind the vertebral bodies, so
they can only be isolated by oblique views; and even then, one oblique view
usually does not show all the joints. For these reasons, little information is
available on the frequency of degenerative changes in these joints.
lateral roentgenogram showing end-plate sclerosis, narrowing of the
intervertebral disc space, and anterior osteophyte formation.
(click image to zoom) Plain lateral roentgenogram showing sclerosis,
narrowing, and osteophyte formation in the C3-4 zygapophyseal joint.
changes of the cervical spine, as seen on plain roentgenograms and more
sophisticated imaging studies, are common in both symptomatic and asymptomatic
people and are thought to be part of the normal aging process (Figure 6).
Degenerative findings are considered to be pathologic when they produce
symptoms. However, with the exception of patients with radicular pain,
localizing neurologic deficits, and nerve root compression as seen on MRI or
CT myelogram studies, the relationship with the patient's neck pain is
image to zoom) A. Normal, plain
lateral roentgenogram of 44-year-old, asymptomatic female. B.
Plain lateral roentgenogram of 54-year-old female, indicating degenerative
changes of zygapophyseal joints most severe at C4-5 and intervertebral disc
degenerative changes at C6-7.
of the most perplexing clinical challenges is to distinguish the source of a
patient's pain when degenerative changes are present. In a review of 200
asymptomatic women, we found that by age 60 to 65, 95% and 70% of women had
degenerative changes as seen on plain roentgenograms.
Boden found MRI abnormalities of the cervical spine in 19% of 63 asymptomatic
volunteers. Fourteen percent occurred in subjects under the age of 40, and 28%
in those over 40.
Zapletal and colleagues
evaluated the atlanto-odontoid joint in 500 consecutive patients who underwent
computed tomography of the brain or paranasal sinuses. They found no
abnormalities before the fourth decade but thereafter the prevalence increased
steadily with age, so that by the ninth decade over 60% had degenerative
changes. In a separate article, Zapletal and associates
evaluated 355 occipital frontal radiographs of the paranasal sinuses for
evidence of osteoarthritis of the lateral C1-C2 joints. Degenerative changes
were found ranging from 5.4% in the sixth decade to 18.2% in the ninth. They
emphasize that these degenerative changes could be a source of upper neck pain
and occipital headaches (Figure 7).
open-mouth roentgenogram showing unilateral degenerative changes at C1-2.
1982, Rothman stated,
"It does not appear that cervical disc degeneration is a brief
self-limited disorder but rather a chronic disease productive of significant
pain and incapacity over an extended period of time."
discussed in the previous sections, degenerative disease of the cervical spine
and neck pain are not synonymous. Degenerative changes are often present in
asymptomatic people, and in some people with neck pain no structural
abnormality can be demonstrated. However, in our experience, Rothman's
statement holds true for patients with neck pain with or without degenerative
1987, we reported on a review of 205 patients initially seen for neck pain in
an office setting.
Patients with previous neck surgery, objective neurologic deficits,
malignancies, or rheumatoid arthritis were excluded. The patients were
re-examined and interviewed an average of 15 years (10 to 25 years) after the
onset of their neck problems. In all patients, lateral roentgenograms were
available for comparison between the initial visit and the final evaluation.
follow-up, 79% had a decrease in pain, and of these, 43% were pain-free;
however 32% had moderate or severe residual pain. Patients who had been
injured and initially had severe pain were most likely to have an
unsatisfactory outcome; however, no other clinical features were of value in
predicting the final result. Initially, 121 patients had injuries, of which 76
were due to motor vehicle accidents. Sixty-eight were involved in litigation,
58 in personal injury claims, and 10 in workman's compensation claims. At
final evaluation, all but 4 claims had been settled, and all of these patients
stated their initial pain had decreased in severity. Interestingly, 23
patients were dissatisfied with the outcome of their litigation. However,
there was no statistical relationship between their level of satisfaction and
the amount of pain or pain relief reported at final interview.
roentgenographic features measured were degenerative changes at each
intervertebral disc space, sagittal diameters of the spinal canal at each disc
space, and cervical lordosis. None of the roentgenographic findings present
initially or developed in the follow-up period correlated with pain or had any
predictive value for pain relief.
important, this study emphasizes that neck pain is frequently not a
self-limited problem, and that many patients will have long-term symptoms that
may be moderately disabling.
is a common problem in our society and at any given time affects about 10% of
the general population. The actual cause of the problem is frequently
difficult to determine. Neck pain in as many as one-third of patients is not
self-limiting and may produce moderate long-term disabilities.
is important to note that extensive research has been performed on low impact
accidents, and how injuries result to occupants from these accidents.
One such research project was performed by The National Highway Traffic
Safety Administration, published by E. Horton, "Why Don't We Buckle
Up," Science Digest, Feb. 1985, in which they state, "a ten-mile an
hour collision is equivalent to catching a two-hundred pound bag of cement
dropped from a second story window. People
don't understand the dynamics of crashes!"
Extrapolate this evidence to a non low impact collision and the
potential effects become even more dramatic.
research study done by The Engineering Society For Advancing Mobility Land Sea
Air and Space, at the University of Texas Health Science Center, page 28,
concluded that in rear-end accidents of 2.5 mph, "Despite having
experienced no neck excursions beyond their voluntary range limits, three of
our four subjects transiently had very mild, but clinical neck discomfort
symptoms." This occurred in
healthy individuals that were prepared for a read-end collision of 2.5 mph!
The research was completed in 1993 and published in the SAE Technical
Paper Series in March 1-5, 1993 issue.
insurance company claims adjusters have assumed that collision injuries
correlate to the vehicle external structural damage and the cost of repair of
the vehicle. The assumption that injuries relate to the amount of external
vehicle damage is in all types of crashes has no scientific basis. (Nordhoff
and Emori 1996).
absence or presence of vehicle damage is not a reliable indicator of injury
potential in rear end impacts. Based upon the principle of conservation of
energy, any energy, which does not go into damaging the vehicle, must be
converted into kinetic energy, which is the source of patient/occupant injury
of the very large mass of motor vehicles, even the smallest speed collisions
generate significant kinetic energy. The kinetic energy is transferred into
the struck vehicle. (Kinetic Energy of the striking vehicle is equal to the
Kinetic Energy after impact plus the vehicle damage- Newton's 3-rd law of
mechanics) The physical facts dictate that the magnitude of passenger injury
can not be totally correlated with vehicle damage. In fact, the smaller the
vehicle damage the greater the kinetic energy available to cause and injury!
This effect is especially relevant in low speed, rear impact collisions (Navin
and Romilly, Smith, Nordhoff and Emori).
development of safety or "no damage" bumpers has been the standard
for the last few decades. They are designed specifically to minimize vehicle
damage in low impact collisions, and there is clear evidence that insurance
property losses have decreased dramatically as a result (Smith).
Unfortunately, when vehicle damage energy is reduced, the energy is
transferred into kinetic energy that causes patient injury. Current bumper
standards have the effect of reducing property damage while subjecting the
occupants to a more violent ride and increasing the probability occupant
injury. (Navin, Smith). Published experts (Navin and Rommily) in motor vehicle
accidents have completed experiments and made observations that degree of
patient/passenger injury is not related to the size, speed, or magnitude of
damage of the involved vehicles.
cervical spine is especially vulnerable to trauma because of the physical
dynamics involved in the actual force, as well as the inherent weakness of the
cervical spine or manner in which the injury occurred. Even a slight impact
can produce a large number of pounds of force on the head and neck. For
example, a 3500 lb. automobile traveling a mere 10 miles per hour would strike
an immovable car with some 25 tons of force. This force on the patients
cervical spine is magnified because the base of the neck acts as a fulcrum and
the actual neck itself is a lever which propels the head and neck backwards,
forwards and side to side.
cervical spine is the weakest area of the spine and also the most mobile. The
bones of the neck are the smallest in the spine, and comprised of over 30
small joints. Each joint about the size of an adult human's smallest finger.
Because of the small size and greater mobility, there is greater potential for
injury. Adding to the neck's weakness is the fact that the cervical spine is
perched on top of a relatively immobile thoracic spine. This situation makes
the base of the neck a fulcrum. Much like a bamboo stick, stuck in the ground.
If the stick is forced backward, forward, left or right, it will break where
it is inserted in the ground. The cervical spine also contains the smallest
shock-absorbing disk in the spine, especially between the second and third
vertebrae. The cervical spine serves as a support and foundation to the head,
which weights from 8-12 lbs. The head is therefore supported on an unstable
platform, much like a house being built on quicksand.
vehicle collision patient/passenger injury and clinical prognosis for
recovery, is not related to the damage of their vehicle. Rather, injury and
prognosis are coupled with direction of impact (rear end, awareness, and
head/neck rotation or inclination).