Disc
pain:
Painful conditions
of the disc account for up to 85% of all low back pain.
Discs are located between the bones that make up the spine,
and are made up of two parts. The hard outer wall, called
the annulus, contains the more liquid, gel-like inner
material, called the nucleus. The nucleus acts as a shock
absorber, but is flexible enough to allow motion. With
aging, degeneration or injury, cracks can occur in the
outer annulus. As the nucleus tries to do its job as a
shock absorber, parts of it are forced into the cracks,
spreading the cracks apart, which can be painful. If the
contents of the nucleus leak outside the annulus, chemical
and allergic reactions occur which can inflame the nearby
nerve roots, causing pain.
Facet
joint and supporting structure pain:
The spine is divided
into levels. In addition to the disc in front, the bones
of the spine are separated in the back, at each level,
by two small joints called facet joints. These joints
are designed to guide motion, not to bear weight. If they
should become weight bearing, they can become a source
of pain. Causes of weight bearing include injury or natural
aging. The joints can be injured by overloading or excessive
motion from a fall or motor vehicle accident (traumatic
arthritis). If a disc should degenerate as described before,
the space between the discs becomes smaller, and the facet
joints start to bear weight, which leads to painful degeneration
(osteoarthritis). Bone spurs and enlargement of the supporting
structures (ligaments) can then narrow the openings through
which the nerves have to pass to exit the spine, possibly
causing pinching or irritation of said nerves.
Of all patients with chronic low back and neck pain,
the facet joints are responsible 10% of the time in the
low back, and 35% of the time in the neck. If pain is
caused by injury, the percentages increase to 35% in the
low back and 70% in the neck.
Spinal
Stenosis:
Narrowing by bulging
or herniated discs, bone spur formation, and enlargement
of the supporting structures can leave too little room
for the nerve tissues. This can lead to pinching, irritation
and inflammation, all of which can be painful.
Alignment
Problems:
The sacroiliac joints
are located where the spine joins the pelvis. Alignment
problems can be experienced in both of the sacroiliac
joints. In the low back, alignment problems account for
about 5% of chronic back pain, but are the most common
cause of acute intermittent pain. As with all of the other
conditions discussed here, alignment problems can exist
without pain. These are treated with specific exercises
and not by injection. It is important to correct such
alignment problems, if possible, even if they are not
a cause of pain, because injections for other diagnoses
will be more effective and will last longer.
Muscle
and Tendons
Although rarely the
origin of low back pain, the muscles are usually involved,
especially if there is protective muscle spasm. With pain
from other causes, activity usually decreases and the
back muscles become weak. Weak muscles fatigue more easily
and fatigued muscles are painful. Injury to where the
muscles attach to the bones is more common, and leads
to painful chronic inflammation. Weak muscles are treated
by exercise, especially after the cause of the pain has
been treated. Inflamed attachments are treated by medication,
exercise, and injection.
In the neck, muscles are a more common cause of pain,
especially if there has been an injury. Muscles are the
main supporting structure of the head on the flexible
spine. Another area that is easily injured is where the
arm joins the chest. This attachment is made entirely
of muscle and forces are often transmitted up the arm
to this "weak link."
Myofascial
Pain Syndrome (MFPS) and Fibromyalgia
MFPS is a muscle condition
caused by injury that is characterized by small pea shaped
nodules called trigger points. It is more common in the
neck, but can cause pain in the low back as well. The
injury can be one big injury or smaller repetitive injuries.
The trigger points are treated by injection, stretching
and physical therapy. They usually do not respond to anti-inflammatory
medications. Fibromyalgia is a generalized condition the
cause of which is unknown. It is characterized by tender
points, weakness and fatigue. The tender points are different
from trigger points because they do not respond to medication.
The treatment for fibromyalgia is aerobic exercise, careful
strengthening, medications for pain, sleep, and inflammation,
and relaxation.
Other Resources
