Pain in the back may be caused by strain on muscles or a "slipped" intervertebral disk, or it may be
affiliated with some type of disorder of the bones and
parts of the spinal column.
The twenty-four
vertebrae that make up the spinal column (seven cervical, twelve thoracic, and five lumbar) extend from the base of the
skull to the sacrum, the triangular "centerpiece" of the pelvis. The vertebrae are separated by pads of tough, elastic cartilage---the
intervertebral disks---which give the
spine its flexibility and also act as shock absorbers. The bones are also bound together by
strong ligaments and by
several groups of powerful
muscles that run mainly in two bands on
either side of the backbone. The spine acts as the central girder of the skeleton; it also provides a protective
tunnel for the spinal cord (which reaches from the brain down to the level of the
second lumbar vertebra) and the nerves that branch from it.
Most commonly, backache is caused by strain of the
muscles around the lower part of the spine. This may be due to unaccustomed exercise---a weekend
spent shoveling snow, for example---or to sitting for
prolonged periods in an
incorrect posture. Strain on the spine is least when the back is straight; a chair that
forces the spine into a curve is likely to provoke chronic back strain.
A separate,
acutely painful type of
backache also originating in the muscles is lumbago. Here the pain often is localized to one
extremely painful spot in the muscles, usually in the lower lumbar region and slightly to one side of the midline.
Lumbago is often experienced
after a combination of
unaccustomed exercise and cold---digging the garden in spring, for example---and may be
severe enough for the
victim to be unable to move out of bed. The cause is
believed to be spasm of a group of
muscle fibers. Even with no treatment other than rest and simple pain-relieving drugs, such as aspirin, the condition resolves within a few days; in some cases recovery may be hastened by injection of a mixture of a local anesthetic and
steroid drug into the "trigger spot."
The
second common cause of
sudden severe backache is
damage to one of the intervertebral disks in the lumbar region of the spine. Damage is most likely to occur when the person is
lifting a heavy weight
while his back is curved. Pressure on the disk, which consists of a tough capsule with a soft, elastic center, may rupture the capsule and allow part of the central nucleus to protrude. If this protrusion
extends into the spinal
canal it may press on one of the
spinal nerves or even on the spinal cord. Typically, this pressure causes pain extending down the main sciatic nerve, which runs from the buttocks to the foot. The pain is made worse by coughing, straining, or
bending the back. If the symptoms persist there may also be loss of feeling in the foot or lower part of the leg and some muscular weakness.
The basic treatment of
prolapsed disk (or "slipped disk") is rest, with the person lying flat on his back in bed. Rest for two weeks, sometimes more, often
allows the disk to
reabsorb the protrusion and the damaged capsule to heal. If the symptoms from pressure on the
spinal nerves are severe, or if they do not resolve with simple rest, traction may be added: Weights are attached to the legs to
lengthen the spine, thus
pulling the vertebrae apart and promoting return of the disk to its
normal condition. The most
radical treatment, which may be necessary if the prolapse, is surgical excision of the damaged portion of the disk.
Unfortunately, anyone who has
suffered a prolapsed disk is at risk of recurrence; once the acute
symptoms have settled, some
program of preventative treatment is important. This will
include exercises to strengthen the muscles that support the spine and instruction on posture and the safe, correct way to lift weights, tie one's shoes, and perform other
simple daily activities. Sometimes a physician may advise the wearing of a
protective and supporting corset.
The third common
cause of sudden backache is a minor displacement of one vertebra relative to its neighbors. Just how frequently this problem
occurs is a matter of dispute within the
medical profession. Some physicians (and all osteopaths and chiropractors) believe that most
episodes of backache can be relieved by manipulation of the spine, thus
encouraging the bones to
return to their normal alignment. Without a doubt,
spinal manipulation often does
relieve symptoms, but reliance on this method can be dangerous if the pain is due to one of the rarer
causes of backache, such as a tumor or an infection such as tuberculosis.
Chronic backache may be caused also by arthritis of the
spinal joints. Ankylosing Spondylitis is a severe form of spinal arthritis, especially
common in young men and related to Rheumatoid Arthritis, which may also
affect the spine; both
diseases cause progressive pain and stiffness of the spine. The common degenerative
Osteoarthriitis also affects the spine; most people over the age of 50 have some stiffness of the back from minor
arthritic changes. No specific
treatment is needed for this form of arthritis
unless symptoms develop.
Among the many other
causes of backache are
infections (tuberculosis was especially
common in the last
century and is still a major problem in
developing countries), tumors of the bones and of the spinal cord and nerves, and the metastasis (spread) of cancer cells to the spine. For that reason, full investigation---including X-ray studies of the
spine and blood tests---is
needed before treatment is
given in any case in which the cause of the pain is not obvious.
Most
episodes of backache are preventable: With correct posture, care in lifting weights, and regular exercise to
maintain muscle tone, the
joints in the back
should remain as trouble-free as those elsewhere in the body.