This page contains general information about spinal stenosis.
It describes the causes of spinal stenosis, symptoms of spinal stenosis,
diagnosis of spinal stenosis, and treatments for of spinal stenosis.
Spinal stenosis is a narrowing of spaces in the spine
(backbone) that results in pressure on the spinal cord and/or nerve
roots. This disorder usually involves the narrowing of one or more of
three areas of the spine: (1) the canal in the center of the column
of bones (vertebral or spinal column) through which the spinal cord
and nerve roots run, (2) the canals at the base or roots of nerves branching
out from the spinal cord, or (3) the openings between vertebrae (bones
of the spine) through which nerves leave the spine and go to other parts
of the body. The narrowing may involve a small or large area of the
spine. Pressure on the lower part of the spinal cord or on nerve roots
branching out from that area may give rise to pain or numbness in the
legs. Pressure on the upper part of the spinal cord (that is, the neck
area) may produce similar symptoms in the shoulders, or even the legs.
Who Gets Spinal Stenosis?
This disorder is most common in people over 50 years of
age. However, it may occur in younger people who are born with a narrowing
of the spinal canal or who suffer an injury to the spine.
Anatomy of the Spine - What Structures of the Spine Are Involved?
The spine is a column of 26 bones that extend in a line
from the base of the skull to the pelvis (see
Figure 1). Twenty-four of the bones are called vertebrae. The bones
of the spine include 7 cervical vertebrae in the neck; 12 thoracic vertebrae
at the back wall of the chest; 5 lumbar vertebrae at the inward curve
(small) of the lower back; the sacrum, composed of 5 fused vertebrae
between the hip bones; and the coccyx, composed of 3 to 5 fused bones
at the lower tip of the vertebral column. The vertebrae link to each
other and are cushioned by shock-absorbing disks that lie between them.
The vertebral column provides the main support for the
upper body, allowing humans to stand upright or bend and twist, and
it protects the spinal cord from injury. Following are structures of
the spine most involved in spinal stenosis.
Intervertebral disks - pads of cartilage between vertebrae
that act as shock absorbers.
Facet joints - joints located on both sides and on the top and
bottom of each vertebra. They connect the vertebrae to each other
and permit back motion.
Intervertebral foramen (also called neural foramen) - an opening
between vertebrae through which nerves leave the spine and extend to
other parts of the body.
Lamina - part of the vertebra at the upper portion of the
vertebral arch that forms the roof of the canal through which the
spinal cord and nerve roots pass.
Ligaments - elastic bands of tissue that support the spine by
preventing the vertebrae from slipping out of line as the spine
moves. A large ligament often involved in spinal stenosis is the
ligamentum flavum, which runs as a continuous band from lamina to
lamina in the spine.
Pedicles - narrow stem-like structures on the vertebrae that
form the walls of the bottom part of the vertebral arch.
Spinal cord/nerve roots - a major part of
the central nervous system that extends from the base of the brain
down to the lower back and that is encased by the vertebral column.
It consists of nerve cells and bundles of nerves. The cord connects
the brain to all parts of the body via 31 pairs of nerves that
branch out from the cord and leave the spine between vertebrae
(see Figure 2).
Synovium - a thin membrane that produces fluid to lubricate
the facet joints, allowing them to move easily.
Vertebral arch - a circle of bone around the canal through
which the spinal cord passes. It is composed of a floor at the back
of the vertebra, walls (the pedicles), and a ceiling where two
laminae join.
What Causes Spinal Stenosis?
The normal vertebral canal (see Figure 3) provides adequate room for the
spinal cord. Narrowing of the canal, which occurs in spinal stenosis, may be inherited or acquired.
Some people inherit a small spinal canal (see Figure 4) or
have a curvature of the spine (scoliosis) that produces
pressure on nerves and soft tissue and compresses or stretches ligaments.
In an inherited condition called achondroplasia, defective bone formation
results in abnormally short and thickened pedicles that reduce the diameter
of (distance across) the spinal canal.
Acquired Conditions
Acquired conditions that can cause spinal stenosis are explained in more
detail in the sections that follow.
Degenerative (Aging) Conditions, Including Osteoarthritis
Spinal stenosis most often results from a gradual, degenerative
aging process. Either structural changes or inflammation can begin the
process. As people age, the ligaments of the spine may thicken and calcify
(harden from deposits of calcium salts). Bones and joints may also enlarge,
and osteophytes (bone spurs) may form. When the health of one part of
the spine fails, it usually places increased stress on other parts of
the spine. For example, a degenerative condition affecting the facet
joints may eventually cause secondary changes, such as a herniated (bulging)
disk that places pressure on the spinal cord or nerve root (see Figure 5).
When a segment of the spine becomes too mobile, the capsules
(enclosing membranes) of the facet joints thicken in an effort to stabilize
the segment, and bone spurs may occur. This decreases the
space (neural foramen) available for nerve roots leaving the spinal
cord.
Aging - Aging with secondary changes is the most common cause
of spinal stenosis. Two forms of arthritis that may affect the spine
are osteoarthritis and rheumatoid arthritis.
Osteoarthritis is the most common form of arthritis and is more likely
to occur in middle-aged and older people. It is a chronic, degenerative
process that may involve multiple joints of the body. It wears away
the surface cartilage layer of joints, and is often accompanied by overgrowth
of bone, formation of bone spurs, and impaired function. If the degenerative
change affects the facet joint(s) and the disk, the condition is sometimes
referred to as spondylosis. This condition may be accompanied by disk
degeneration, and an enlargement or overgrowth of bone that narrows
the central and root canals.
Spondylolysthesis - Spondylolysthesis, a condition in which one
vertebra slips forward on another, may result from a degenerative condition
or an accident, or may be acquired at birth. Poor alignment of the spinal
column when a vertebra slips forward onto the one below it can place
pressure on the spinal cord or nerve roots at that place.
Rheumatoid Arthritis - Rheumatoid arthritis usually affects people at an earlier
age than osteoarthritis does and is associated with inflammation and
enlargement of the soft tissues of the joints. Although not a common
cause of spinal stenosis, damage to ligaments, bones, and joints that
begins as synovitis (inflammation of the synovial membrane) has a severe
and disrupting effect on joint function. The portions of the vertebral
column with the greatest mobility (for example, the neck area) are often
the ones most affected in people with rheumatoid arthritis.
Nonarthritic Acquired Spinal Stenosis
Conditions not related to arthritis or degenerative disease are causes of
acquired spinal stenosis:
Tumors of the Spine - Tumors of the spine are abnormal growths of
soft tissue that may affect the spinal canal directly by inflammation
or by growth of tissue into the canal. Tissue growth may lead to
bone resorption (bone loss due to overactivity of certain bone cells)
or displacement of bone and the eventual collapse of the supporting
framework of the vertebral column.
Trauma - Trauma (accidents) may either dislocate the
spine and the spinal canal or cause burst fractures that produce
fragments of bone that penetrate the canal.
Post-Surgery - Although surgery that involves fusion (union) of vertebrae may be
skillfully performed, tissue swelling after surgery may place pressure
on the spinal cord.
Paget's Disease - Paget's disease of bone is a chronic (long-term)
disorder that typically results in enlarged and deformed bones.
Excessive bone breakdown and formation cause thick and fragile bone.
As a result, bone pain, arthritis, noticeable deformities, and fractures
can occur. The disease can affect any bone of the body, but is often
found in the spine. The blood supply that feeds healthy nerve tissue
may be diverted to the area of involved bone. Also, structural deformities
of the involved vertebrae can cause narrowing of the spinal canal,
producing a variety of neurological symptoms.
Fluorosis - Fluorosis is an excessive level of fluoride
in the body. It may result from chronic inhalation of industrial
dusts or gases contaminated with fluorides, prolonged ingestion
of water containing large amounts of fluorides, or accidental ingestion
of fluoride-containing insecticides. The condition may lead to calcified
spinal ligaments or softened bones and to degenerative conditions
like spinal stenosis.
What Are the Symptoms of Spinal Stenosis?
Spaces within the spine can narrow without producing any
symptoms. However, if narrowing places pressure on the spinal cord (spinal cord compression) or
nerve roots, there may be a slow onset and progression of symptoms.
The back itself may or may not hurt. More often, people experience numbness,
weakness, cramping, or general pain in the legs that occurs during flexing
the lower back while sitting. (The flex position "opens up"
the spinal column, enlarging the spaces between vertebrae at the back
of the spine.) If a disk between vertebrae is compressed, people may
feel pain radiating down the leg (sciatica).
People with more severe stenosis may experience abnormal
bowel and bladder function and foot disorders. For example, cauda equina
syndrome is a partial or complete loss of control of the bowel or bladder
and sometimes sexual function; it is due to compression of the collection
of spinal roots that descend from the lower part of the spinal cord
and occupy the vertebral canal below the cord. In very rare instances,
compression above the area where the lumbar vertebrae and sacrum meet
results in partial or complete paralysis of the legs.
How Is Spinal Stenosis Diagnosed?
The doctor may use a variety of approaches to diagnose spinal stenosis and
rule out other conditions.
Medical history - The patient tells the doctor details about
symptoms and about any injury, condition, or general health problem that
might be causing the symptoms.
Physical Examination - The doctor, (1) examines the patient to
determine the extent of limitation of movement; (2) checks for pain or
symptoms when the patient hyperextends the spine (bends backwards);
and (3) looks for the loss of extremity reflexes, which may be related to
numbness or weakness in the arms or legs.
X-ray - An x-ray beam is passed through the back to produce a
two-dimensional picture. An x ray may be done before other tests to look
for signs of an injury, tumor, or inherited abnormality. This test can
show the structure of the vertebrae and the outlines of joints, and can
detect calcification.
MRI (magnetic
resonance imaging) - energy from a powerful magnet (rather than x
rays) produces signals that are detected by a scanner and analyzed by
computer. This produces a series of cross-sectional images ("slices")
and/or a three-dimensional view of parts of the back. An MRI is particularly
sensitive for detecting damage or disease of soft tissues, such as the disks
between vertebrae or ligaments. It shows the spinal cord, nerve roots,
and surrounding spaces, as well as enlargement, degeneration, or tumors.
Computerized Axial Tomography (CAT) -
X-rays are passed through the back at different angles, detected by a
scanner, and analyzed by a computer. This produces a series of
cross-sectional images and/or three-dimensional views of the parts of
the back. The scan shows the shape and size of the spinal canal, its
contents, and structures surrounding it.
Myelogram - With a myelograma, a liquid dye that x-rays cannot
penetrate is injected into the spinal column. The dye circulates
around the spinal cord and spinal nerves, which appear as white
objects against bone on an x-ray film. A myelogram can show pressure
on the spinal cord or nerves from herniated disks, bone spurs, or
tumors.
Bone scan - With a bone scan, an injected radioactive material
attaches itself to bone, especially in areas where bone is actively
breaking down or being formed (hot spots). The test can detect fractures,
tumors, infections, and arthritis, but may not tell one disorder from
another. Therefore, a bone scan is usually performed along with other
tests.
Nonsurgical treatment of spinal stenosis may be provided
by internists or general practitioners. The disorder is also treated
by specialists such as pain management physicians, rheumatologists, who
treat arthritis and related disorders; and neurologists, who treat nerve
diseases. Orthopaedic surgeons and neurosurgeons also provide nonsurgical
treatment and perform spinal surgery if it is required. Allied health
professionals such as physical therapists and massage therapists may also
help treat patients.
What Are Some Nonsurgical Treatments for Spinal Stenosis?
In the absence of severe or progressive nerve involvement, a doctor may
prescribe one or more of the following conservative treatments:
Opioid Therapy - Opioid Therapy (use of narcotic medication) is an appropriate option
despite most physicians opiod-phobic concerns. Incidence of addiction from
opioid therapy is less than 1% of those treated. There is a difference
between dependence and addiction, they are NOT interchangeable
More on the approipriate
use of opioid therapy...
Nonsteroidal Anti-inflammatory Drugs - Nonsteroidal
anti-inflammatory drugs, such as aspirin, naproxen, ibuprofen (Advil, Motrin), or
indomethacin (Indocin), to reduce inflammation and relieve pain. Caution must be used
with long-term use as severe bleeding problems such as stomach ulcers,
can occur.
Analgesics - Analgesics, such as acetaminophen
(Tylenol), to relieve pain. Extreme caution must be used.
Acetaminophen is highly toxic to the liver in amounts greater than 3000mg
per day, and long-term use beyond 7 days can be fatal.
Corticosteroid injections - Corticosteroid injections
into the outermost of the membranes covering the spinal cord and nerve
roots to reduce inflammation and treat acute pain that radiates to the
hips or down a leg. Caution must be used. Make sure this procedure is
performed with fluoroscopy (a type of x-ray) guidance. Also, a condition
called Syringomyelia can occur from
improperly performing this procedure
Restricted activity - Restricted activity (varies
depending on extent of nerve involvement).
Allied Health Professionals - Physical therapy, massage
therapy and/or prescribed exercises to maintain motion of the spine and
build endurance, which help stabilize the spine. Remember, if it hurts to do
it, DON'T DO IT!
External Braces - A lumbar brace or corset to provide
some support and help the patient regain mobility. This approach is
sometimes used for patients with weak abdominal muscles or older patients
with degeneration at several levels of the spine. For cervical spinal
stenosis, a soft, or hard collar can be used to restrict movement.
When Should Surgery Be Considered and What Is Involved?
In many cases, the conditions causing spinal stenosis
cannot be permanently altered by nonsurgical treatment, even though
these measures may relieve pain for a time. To determine the extent
to which nonsurgical treatment will help, a doctor seldom recommends
surgery during the first 3 months of treatment. However, surgery might
be considered within the 3-month period if a patient experiences numbness
or weakness that interferes with walking, impaired bowel or bladder
function, or other neurological involvement.
The purpose of surgery is to relieve pressure on the spinal
cord or nerves and restore and maintain alignment and strength of the
spine. This can be done by removing, trimming, or adjusting diseased
parts that are causing the pressure or loss of alignment. The most common
surgery is called decompressive laminectomy: removal of the lamina (roof)
of one or more vertebrae to create more space for the nerves. A surgeon
may perform a laminectomy with or without fusing vertebrae or removing
part of a disk. Various devices may be used to enhance fusion and strengthen
unstable segments of the spine following decompression surgery.
Patients with spinal stenosis caused by spinal trauma or achondroplasia
may need surgery at a young age. When surgery is required in patients with
achondroplasia, laminectomy (removal of the roof) without fusion is usually
sufficient.
Surgery is almost never performed when the only presenting symptom is pain.
Pain can be managed by a pain management physician specialist.
All surgery, particularly that involving general anesthesia
and older patients, carries risks. The most common complications of
surgery for spinal stenosis are a tear in the membrane covering the
spinal cord at the site of the operation, infection, or a blood clot
that forms in the veins. These conditions can be treated but may prolong
recovery.
A condition known as Syringomyelia, while
uncommon, is a risk factor.
What Are the Long-Term Outcomes of Surgical Treatment for Spinal Stenosis?
Removal of the obstruction that has caused the symptoms
usually gives patients some relief; most patients have less leg pain
and are able to walk better following surgery. However, if nerves were
badly damaged prior to surgery, there often is some remaining pain or
numbness or no improvement. Also, the degenerative process will likely
continue, and pain or limitation of activity may reappear 5 or more
years after surgery. Pain management from a qualified pain management
physician specialist would be appropriate for pain.
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