Herniated disk
You’ve probably heard people say they have a "slipped" or
"ruptured" disk in the back. What they’re actually describing is a
herniated disk, a common source of lower back pain.
Disks are soft, rubbery pads found between the hard bones (vertebrae) that make up the
spinal column. In the middle of the spinal column is the spinal canal, a hollow space that
contains the spinal cord and other nerve roots. The disks between the vertebrae allow the
back to flex or bend. Disks also act as shock absorbers.
The outer edge of the disk is a ring of gristle-like cartilage called the annulus. The
center of the disk is a gel-like substance called the nucleus. A disk herniates or
ruptures when part of the center nucleus pushes the outer edge of the disk into the spinal
canal, and puts pressure on the nerves
Information about herniated disk
The spinal column is made up of 26 vertebrae that are joined together and permit
forward and backward bending, side bending, and rotation of the spine. Five distinct
regions comprise the spinal column, including the cervical (neck) region, thoracic (chest)
region, lumbar (low back) region, sacral and coccygeal (tailbone) region. The cervical
region consists of seven vertebrae, the thoracic region includes 12 vertebrae, and the
lumbar region contains five vertebrae. The sacrum is composed of five fused vertebrae,
which are connected to four fused vertebrae forming the coccyx. Intervertebral disks lie
between each adjacent vertebra.
Each disk is composed of a gelatinous material in the center, called the nucleus
pulposus, surrounded by rings of a fiberous tissue (annulus fibrosus). In disk herniation,
an intervertebral disk's central portion herniates or slips through the surrounding
annulus fibrosus into the spinal canal, putting pressure on a nerve root. Disk herniation
most commonly affects the lumbar region between the fifth lumbar vertebra and the first
sacral vertebra. However, disk herniation can also occur in the cervical spine. The
incidence of cervical disk herniation is most common between the fifth and sixth cervical
vertebrae. The second most common area for cervical disk herniation occurs between the
sixth and seventh cervical vertebrae. Disk herniation is less common in the thoracic
region.
Predisposing factors associated with disk herniation include age, gender, and work
environment. The peak age for occurrence of disk herniation is between 20-45 years of age.
Studies have shown that males are more commonly affected than females in lumbar disk
herniation by a 3:2 ratio. Prolonged exposure to a bent-forward work posture is correlated
with an increased incidence of disk herniation.
There are four classifications of disk pathology:
- A protrusion may occur where a disk bulges without rupturing the annulus fibrosis.
- The disk may prolapse where the nucleus pulposus migrates to the outermost fibers of the
annulus fibrosis.
- There may be a disk extrusion, which is the case if the annulus fibrosis perforates and
material of the nucleus moves into the epidural space.
- The sequestrated disk may occur as fragments from the annulus fibrosis and nucleus
pulposus are outside the disk proper.
Causes of herniated disk
Disks have a high water content. As people age, the water content decreases, so the
disk begins to shrink and the spaces between the vertebrae get narrower. Also, the disk
itself becomes less flexible. Other conditions that can weaken the disk include:
- wear-and-tear
- excessive weight which can squeeze the softer material of the nucleus out toward the
spinal canal
- bad posture
- improper lifting
- sudden pressure (which may be slight)
The fibrous outer ring may tear. As the disk material pinches and puts pressure on the
nerve roots, pain results. Sometimes fragments of the disk enter the spinal canal where
they can damage the nerves that control bowel and urinary functions.
Symptoms of Herniated disk
Low back pain affects four out of five people. So pain alone isn’t enough to
recognize a herniated disk. However, if the back pain is the result of a fall or a blow to
your back, don’t hesitate to contact a doctor. The most common symptom of a herniated
disk is sciatica, a sharp, often shooting pain that extends from the buttocks down the
back of one leg. This is caused by pressure on the spinal nerve. Other symptoms include
- Weakness in one leg
- Tingling (a "pins-and-needles" sensation) or numbness in one leg
- Loss of bladder or bowel control (If you also have weakness in both legs, you could have
a serious problem. Seek immediate attention.)
- A burning pain centered in the back
Diagnosis of herniated disk
Your medical history is key to a proper diagnosis. You may have a history of back pain
with gradually increasing leg pain. Often a specific injury causes a disk to herniate. A
physical examination can usually determine which nerve roots are affected (and how
seriously). A simple x-ray may show evidence of disk or degenerative spine changes.
Treatment
Drugs
Unless serious neurologic symptoms occur, herniated disks can initially be treated with
pain medication and up to 48 hours of bed rest. There is no proven benefit from resting
more than 48 hours. Patients are then encouraged to gradually increase their activity.
Pain medications, including antiinflammatories, muscle relaxers, or in severe cases,
narcotics, may be continued if needed.
Epidural steroid injections have been used to decrease pain by injecting an
antiinflammatory drug, usually a corticosteroid, around the nerve root to reduce
inflammation and edema (swelling). This partly relieves the pressure on the nerve root as
well as resolves the inflammation.
Physical therapy
Physical therapists are skilled in treating acute back pain caused by the disk
herniation. The physical therapist can provide noninvasive therapies, such as ultrasound
or diathermy to project heat deep into the tissues of the back or administer manual
therapy, if mobility of the spine is impaired. They may help improve posture and develop
an exercise program for recovery and long-term protection. Appropriate exercise can help
take pressure off inflamed nerve structures, while improving overall posture and
flexibility. Traction can be used to try to decrease pressure on the disk. A lumbar
support can be helpful for a herniated disk at this level as a temporary measure to reduce
pain and improve posture.
Surgery
Surgery is often appropriate for conditions that do not improve with the usual
treatment. In this event, a strong, flexible spine is important for a quick recovery after
surgery. There are several surgical approaches to treating a herniated disk, including the
classic discectomy, microdiscectomy, or percutanteous discectomy. The basic differences
among these procedures are the size of the incision, how the disk is reached surgically,
and how much of the disk is removed.
Discectomy is the surgical removal of the portion of the disk that is putting pressure
on a nerve causing the back pain. In the classic disectomy, the surgeon first enters
through the skin and then removes a bony portion of the vertebra called the lamina, hence
the term laminectomy. The surgeon removes the disk material that is pressing on a nerve.
Rarely is the entire lamina or disk entirely removed. Often, only one side is removed and
the surgical procedure is termed hemi-laminectomy.
In microdiscectomy, through the use of an operating microscope, the surgeon removes the
offending bone or disk tissue until the nerve is free from compression or stretch. This
procedure is possible using local anesthesia. Microsurgery techniques vary and have
several advantages over the standard discectomy, such as a smaller incision, less trauma
to the musculature and nerves, and easier identification of structures by viewing into the
disk space through microscope magnification.
Percutaneous disk excision is performed on an outpatient basis, is less expensive than
other surgical procedures, and does not require a general anesthesia. The purpose of
percutaneous disk excision is to reduce the volume of the affected disk indirectly by
partial removal of the nucleus pulposus, leaving all the structures important to stability
practically unaffected. In this procedure, large incisions are avoided by inserting
devices that have cutting and suction capability. Suction is applied and the disk is
sliced and aspirated.
Athroscopic microdiscectomy is similar to percutaneous discectomy, however it
incorporates modified arthroscopic instruments, including scopes and suction devices. A
suction irrigation of saline solution is established through two entry sites. A video
discoscope is introduced from one site and the deflecting instruments from the opposite
side. In this way, the surgeon is able to search and extract the nuclear fragments under
direct visualization.
Laser disk decompression is performed using similar means as percutaneous excision and
arthroscopic microdiscectomy, however laser energy is used to remove the disk tissue.
Here, laser energy is percutanteously introduced through a needle to vaporize a small
volume of nucleus pulposus, thereby dropping the pressure of the disk and decompressing
the involved neural tissues. One disadvantage of this procedure is the high initial cost
of the laser equipment. It is important to realize that only a very small percentage of
people with herniated lumbar disks go on to require surgery. Further, surgery should be
followed by appropriate rehabilitation to decrease the chance of reinjury.
Chemonucleolysis
Chemonucleolysis is an alternative to surgical excision. Chymopapain, a purified enzyme
derived from the papaya plant, is injected percutaneously into the disk space to reduce
the size of the herniated disks. It hydrolyses proteins, thereby decreasing water-binding
capacity, when injected into the nucleus pulposus inner disk material. The reduction in
size of the disk relieves pressure on the nerve root.
Spinal fusion
Spinal fusion is the process by which bone grafts harvested from the iliac crest (thick
border of the ilium located on the pelvis) are placed between the intervertebral bodies
after the disk material is removed. This approach is used when there is a need to
reestablish the normal bony relationship between the vertebrae. A total discectomy may be
needed in some cases because lumbar spinal fusion can help prevent recurrent lumbar disk
herniation at a particular level.
Alternative treatment
Acupuncture involves the use of fine needles inserted along the pathway of the pain to
move energy locally and relieve the pain. An acupuncturist determines the location of the
nerves affected by the herniated disk and positions the needles appropriately. Massage
therapists may also provide short-term relief from a herniated disk. Following manual
examination and x-ray diagnosis, chiropractic treatment usually includes manipulation to
correct muscle and joint malfunctions, while care is taken not to place an additional
strain on the injured disk. If a full trial of conservative therapy fails, or if
neurologic problems (weakness, bowel or bladder problems, and sensory loss) develop, the
next step is usually evaluation by an orthopedic surgeon.
Prognosis
Only 5-10% of patients with unrelenting sciatica and neurological involvement, leading
to chronic pain of the lumbar spine, need to have a surgical procedure performed. This
strongly suggests that many patients with herniated disks at the lumbar level respond well
to conservative treatment. For those patients who do require surgery for lumbar disk
herniation, the reviewed procedures of nerve root decompression caused by disk herniation
is favorable. Results of studies varied from 60-90% success rates. Disk surgery has
progressively evolved in the direction of decreasing invasiveness. Each surgical procedure
is not without possible complications, which can lead to chronic low back pain and
restricted lifestyle.
Prevention
Proper exercises to strengthen the lower back and abdominal muscles are key in
preventing excess stress and compressive forces on lumbar disks. Good posture will help
prevent problems on cervical, thoracic, and lumbar disks. A good flexibility program is
critical for prevention of muscle and spasm that can cause an increase in compressive
forces on disks at any level. Proper lifting of heavy objects is important for all muscles
and levels of the individual disks. Good posture in sitting, standing, and lying down is
helpful for the spine. Losing weight, if needed, can prevent weakness and unnecessary
stress on the disks caused by obesity. Choosing proper footwear may also be helpful to
reduce the impact forces to the lumbar disks while walking on hard surfaces. Wearing
special back support devices may be helpful if heavy lifting is required with combinations
of twisting. |
