Herniated = from “hernia,” a part of the body that bulges out through an abnormal opening
Disc = the disk-shaped cushions between the bones of the spine
The vertebral column (also called the spinal column or backbone) is made up of 33 bones known as vertebra (plural, vertebrae). Each vertebra is separated from the adjacent vertebrae by intervertebral discs, a spongy but strong connective tissue. The intervertebral discs, along with ligaments and facet joints, connect the individual vertebrae to help maintain the spine’s normal alignment and curvature while also permitting movement.
The image at left shows the entire spinal column from beside and from the front. The bones of the spinal column are orange in color, and the intervertebral discs are white.
In the center of the spinal column there is an open channel called the spinal canal. The spinal cord and spinal nerves are located in the spinal canal, where they are surrounded by spinal fluid and protected by the strong spinal column. On each side of the spine, small openings between adjacent vertebrae called foramina (singular, foramen) allow nerve roots to enter and exit the spinal canal.
The spine is divided into the following distinct regions:
- Cervical spine – consists of seven vertebrae in the neck. These vertebrae are small and allow for the mobile nature of the neck.
- Thoracic spine – consists of 12 vertebrae in the upper and mid-back. These are larger and stronger than the cervical vertebrae. Each thoracic vertebra is attached to a rib on either side. This provides significant stiffness and strength to the thoracic portion of the spine.
- Lumbar spine – usually consists of five vertebrae in the lower back, but may vary between four and six. These vertebrae are the largest because they withstand the greatest amount of force in the spine. The lumbar spine is also more mobile than the thoracic spine. Because of these factors, the lumbar spine is the most frequently affected by degenerative conditions, spinal stenosis, and herniated discs.
- Sacrococcygeal – the very lowest portion of the spine. The sacrococcygeal region consists of one single bone, made of fused vertebrae in the sacrum (five vertebrae) and coccyx (four vertebrae). It attaches to the pelvis on either side. In a small number of people, there may be a disc between the first and second sacral vertebrae. Alternatively, the fifth vertebra in the lumbar (lower) spine may occasionally be fused to the sacrum, leaving only 4 lumbar vertebrae.
A herniated disc occurs when the fibrous outer portion of the disc ruptures or tears, and the jelly-like core squeezes out. When the herniated disc compresses a nearby nerve, as in the image below, the result can be a pinched nerve. A pinched nerve may cause pain, numbness, tingling or weakness in the arms or legs. The substance that makes up the disc’s jelly-like core can also inflame and irritate the nerve, causing additional pain.
A bulging disc occurs when the outer wall of the disc weakens but doesn’t rupture, and “bulges” outward. A herniated disc may actually begin as a bulging disc whose outer wall is then ruptured by a great amount of pressure.
A cervical herniated disc may put pressure on a cervical spinal nerve and can cause symptoms like pain, pins and needles, numbness or weakness in the neck, shoulders, or arms. A large disc herniation in the cervical spine may compress the spinal cord within the spinal canal and cause numbness, stiffness, and weakness in the legs and possibly some difficulty with bowel and bladder control.
A thoracic herniated disc may cause pain in the mid back around the level of the disc herniation. If the disc herniation compresses a thoracic spinal nerve as it travels through the foramen, then pain or numbness may travel around the rib cage from the back to the front of the chest or upper abdomen. A large disc herniation in the thoracic spine may compress the spinal cord within the spinal canal and cause numbness, stiffness and weakness in the legs and possibly some difficulty with bowel and bladder control.
A lumbar herniated disc may cause the following symptoms:
- Intermittent or continuous back pain (this may be made worse by movement, coughing, sneezing, or standing for long periods of time)
- Spasm of the back muscles
- Sciatica — pain that starts near the back or buttock and travels down the leg to the calf or into the foot.
- Muscle weakness in the legs
- Numbness in the leg or foot
- Decreased reflexes at the knee or ankle
- Changes in bladder or bowel function
- Difficulty walking
The symptoms of disc disease may resemble other conditions or medical problems. Always consult a doctor for a diagnosis.
Causes and Risk Factors
Herniated discs can often be the result of degenerative disc disease. As people age, the intervertebral discs lose their water content and ability to cushion the vertebrae. As a result, the discs are not as flexible. Furthermore, the fibrous outer portion of the disc is more likely to rupture or tear.
Acute disc herniations can occur in young, healthy people as a result of an injury or tear to the outer layer of the disc (called the annulus fibrosis) that allows the central, jelly-like portion of the disc (called the nucleus pulposis) to herniate into the spinal canal or foramen.
Tests and Diagnosis
If a patient presents with symptoms associated with disc herniation, the doctor may order the following diagnostic procedures:
- Magnetic resonance (MR) imaging – the best overall method of imaging the spinal cord, nerve roots, intervertebral discs, and ligaments.
- Computerized tomography (CT) scan – a series of X-rays, assembled by a computer into 3-dimensional images of the body’s structures
- Myelography – a procedure that involves injecting a liquid dye into the spinal column followed by a series of X-rays and a computerized tomography (CT) scan. This procedure may provide useful images that reveal indentations of the spinal fluid sac caused by bulging or herniated discs, or bone spurs that might be pressing on the spinal cord or nerves.
- Electromyography (EMG) – tests the electrical activity of a nerve root to help determine the cause of pain.
Since a herniated disc may cause similar symptoms to other degenerative spinal conditions, a surgeon may order a variety of diagnostic procedures to rule out other possible conditions.
Before discussing surgery as an option, the surgeon may initiate the following nonoperative treatments:
- Activity modification
- Patient education on proper body mechanics (to help decrease the chance of worsening pain or damage to the disc)
- Physical therapy, which may include ultrasound, massage, conditioning, and exercise programs
- Weight control
- Medications (to reduce inflammation, control pain and/or relax muscles)
Surgical treatment for a herniated disc will be based on the following:
- The history, severity and duration of pain
- Whether or not the patient has received previous treatments for disc disorders and how effective the treatments were
- Whether or not there is any evidence of neurologic damage such as sensory loss, weakness, impaired coordination, or bowel or bladder problems
Surgery for patients with disc disorders of the spine is usually recommended for those patients who do not find relief with non-operative treatment over a period of 6-12 weeks. Surgery is also recommended in patients who have a neurologic deficit (numbness, weakness or reduced function due to pressure on the spinal cord or nerves). Early intervention in those cases is best in order to maximize the likelihood of neurologic recovery.
Your surgeon may perform the following surgical procedures:
- Microdiscectomy: A procedure that uses a microscope and microsurgical tools to remove the portion of the disc that is pressing against the nerve, relieving the pressure caused by a herniated disc. Microdiscectomy is frequently performed for herniated discs in the certical, thoracic, and lumbosacral spine. This procedure is performed under general anesthesia through a small skin incision over the spine. The muscles of the spine are gently elevated or spread apart to expose a small segment of the spine. A small amount of the back part of the spine, called the lamina and facet joint, is trimmed under high magnification of the microscope to provide safe access to the spinal canal. Using microsurgical techniques, our neurosurgeons identify and remove the herniated piece of the disc while protecting the compressed nerve. Most patients may go home either on the day of surgery or the next morning.
- Anterior (from the front) or lateral (from the side) surgical approaches may be required for large or calcified thoracic disc herniations that cause spinal cord compression.
- Anterior Cervical Discectomy and Fusion (ACDF): a procedure that involves the removal of the herniated disc in the cervical spine through the front of the neck. A fusion surgery may be required to make the spine stable after the discectomy.