Disk herniation is a rupture of fibrous material surrounding the disks that separate the vertebrae of the spine. Each disk is made up of a jelly-like center surrounded by a tough ring of fibres arranged in concentric layers like those of an onion. Any forceful vertical pressure on the disks can cause them to push their fluid contents outward, placing pressure on a spinal nerve thatcan cause both nerve damage and considerable pain. Herniation may occur suddenly from lifting, twisting, or direct injury, or gradually from degenerativechanges. The condition most frequently occurs in the low back region and is also called herniated nucleus pulposus, prolapsed disk, ruptured intervertebral disk, or slipped disk. Disk herniation can also occur in the neck, and lesscommonly, in the chest area.
Depending on the location, the ruptured material may press directly on nerveroots or on the spinal cord, causing a shock-like pain (sciatica) down the legs, weakness, numbness, or problems with bowels, bladder, or sexual function.
The peak age for occurrence of disk herniation is between 20-45 years of age.Males are more commonly affected than females by low-back disk herniation bya 3:2 ratio. A prolonged, bent-forward work posture is linked to increased cases of disk herniation.
X rays, computed tomography scans (CT or CAT scans), and magnetic resonance imaging (MRI) are useful for confirming disk herniation. Myelography is a special x ray in which a dye or air is injected into the patient's spinal canal.The patient lies strapped to a table as the table tilts in various directionsand spot x rays are taken of the spine. Electomyograms (EMGs), measuring theelectrical activity of muscle contractions, assess muscle fatigue associatedwith low back pain.
Unless serious symptoms occur, herniated disks can initially be treated withpain 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. Medications including antiinflammatories, muscle relaxers, or in severe cases, narcotics, may be continued if needed.
Physical therapists can use therapies such as ultrasound or diathermy to project heat deep into the tissues of the back. They can also administer manual therapy, if mobility of the spine is impaired. Physical therapy may also helpimprove posture and develop an exercise program for recovery and long-term protection. Traction can be used to try to decrease pressure on the disk. A lumbar support can be helpful as a temporary measure to reduce pain and improveposture.
Surgery is often appropriate for conditions that do not improve with the usual treatment. A strong, flexible spine is important for a quick recovery aftersurgery. 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 puttingpressure on a nerve causing the back pain. The surgeon first enters throughthe skin and then removes a bony portion of the vertebra called the lamina, hence the term laminectomy. The disk material that is pressing on a nerve is removed. Rarely is the entire lamina or disk removed.
In microdiscectomy, the offending bone or disk tissue is removed with the surgeon using an operating microscope. This procedure can be done under local anesthesia. Advantages include a smaller incision, less injury to the muscles and nerves, and easier identification of structures.
Percutaneous disk excision is performed on an outpatient basis, is less expensive than other surgical procedures, and does not require general anesthesia.The purpose is partial removal of the disk's soft center, leaving all the structures important to stability practically unaffected. In this procedure, large incisions are avoided by inserting devices that have cutting and suctioncapability.
Athroscopic microdiscectomy is similar to percutaneous discectomy. A video scope is introduced through one entry site and surgical instruments through another site. The surgeon is able to search and extract material while directlyobserving what he is doing.
Laser disk decompression is also similar to percutaneous excision and arthroscopic microdiscectomy, however laser energy, introduced through a needle, vaporizes a small portion of the disk's center.
It is important to realize that only a very small percentage of people with herniated low-back disks require surgery. Further, surgery should be followedby appropriate rehabilitation to decrease the chance of reinjury.
Spinal fusion is the process by which bone grafts harvested from the pelvis are placed between the vertebrae after the disk material is removed. In the low back, spinal fusion can help prevent further disk herniation.
Chemonucleolysis is an alternative to surgery. Chymopapain, a purified enzymederived from the papaya plant, is injected into the disk space to relieve pressure on the nerve root.
Acupuncture is an alternative therapy involving the use of fine needles inserted along the pathway of the pain to relieve pain. Massage therapists may also provide short-term relief from a herniated disk. Chiropractic treatment usually includes manipulation to correct muscle and joint malfunctions.
Many patients with herniated disks in the low back respond well to conservative treatment. Only 5-10% of patients with unrelenting sciatica and chronic low-back pain need to have a surgical procedure performed. For those patients who do require surgery, success rates for the above-mentioned procedures varies from 60-90%. Disk surgery has progressively become less invasive, but eachprocedure has possible complications that can lead to chronic low back pain and restricted lifestyle.
Proper exercises to strengthen the lower back and abdominal muscles are key in preventing excess stress on the disks. Good posture, a flexibility program,losing weight, and proper lifting of heavy objects are all important. Properfootwear may reduce impact forces while walking on hard surfaces. Special back-support devices may help if heavy lifting is required with combinations oftwisting.