Back Pain and Disk Disease — The Dana Guide


by Thomas N. Byrne

March, 2007

sections include: watching your backdisk herniationspondylosiscervical spondylotic myelopathylumbar spinal stenosis 

Nearly all of us suffer back or neck pain sometime in our lives. In the United States, that problem is second only to colds as the chief reason individuals see their primary care physicians. When we total up lost productivity and medical costs, backaches are the most expensive chronic illness among Americans 30 to 60 years of age. Fortunately, most people with back and neck pain can return to their usual activities after a few days or weeks of rest and, perhaps, pain-relieving medicines. Most of these cases are probably due to strains and sprains of muscles and ligaments.

Back pain can also herald a serious underlying disease, however, such as cancer, aneurysm, vertebral compression fracture, or infection. Or the problem can arise within the spinal structure, such as a herniated disk or bone spur in the wrong place; these problems can cause severe symptoms (paralysis, sensory loss, and incontinence among them) and eventually irreversible nerve damage. It is important, therefore, to identify the cause of serious back and neck pain. The problems discussed in this section are disk herniation, spondylosis, cervical spondylotic myelopathy, and lumbar spinal stenosis.

Watching Your Back

To understand how pain can arise in the spine, and how problems in the spine can cause you to feel pain elsewhere in your body, it helps to begin with the anatomy of the spine. The spinal column is composed of 30 vertebral bones divided into five regions—cervical, thoracic, lumbar, sacral, and the coccyx (tailbone). Every vertebra is identified according to its place along the spine: for example, L5 is the fifth bone in the lumbar region, and S1 is the first bone in the sacral region. Together the vertebrae form the spinal canal, through which the spinal cord runs from the skull to about the second lumbar vertebra. Below the spinal cord is the cauda equina, a group of nerve roots that innervate our legs and pelvic region. Thus, when doctors perform a spinal tap, or lumbar puncture, the needle enters the spinal canal below the spinal cord.

Each vertebra has two facet joints that fit between the facet joints of the vertebrae immediately above and below. This arrangement makes the spine very flexible while still protecting the spinal cord. Nerve roots exit the cord to each side through spaces between pairs of vertebrae. (In the thoracic and lumbar areas, each root is numbered with the vertebra above it: for example, T12, L1, and so on. In the cervical area, each nerve root is numbered with the vertebra below it: for example, C5, C6.) These nerve roots carry sensory impulses from all parts of the body below the head to the spinal cord, which in turn carries them to our brain. These roots also carry all motor impulses to our muscles. Bundled in them are the autonomic nerves that connect to our internal organs, including the heart, lungs, intestines, bladder, and sweat glands. Obviously, proper functioning of these nerve roots is essential to how our bodies work.

This anatomical arrangement also explains how our first sign of a spinal problem can be pain that we feel in other parts of the body, a condition known as referred pain or radicular pain. The best known example is sciatica. A herniated disk or bone spur can put pressure on a low lumbar or sacral nerve root (L4, L5, or S1). When this root is irritated, a person can feel “pins and needles” or pain from the back down through the buttock into the back of the thigh and calf and, at times, even into the foot. A physician can sometimes diagnose the precise nerve root involved from listening to the patient’s history of pain and numbness and performing an examination. For example, if the numbness goes into the big toe, the problem is apt to be with the L5 nerve root. If the numbness extends into the little toe and a person’s ankle reflex is diminished, the nerve root affected is more likely to be S1.

Similarly, doctors can investigate problems in the cervical area by testing deep tendon reflexes in a person’s arms. Our reflex in the biceps muscle depends predominantly on the C5 nerve root, in the triceps on the C7 root, and in the brachioradialis on the C6 root. These tests are done by tapping the tendon for muscle contraction.

Disk Herniation

In the cervical, thoracic, and lumbar regions of the spine, there is a disk between each pair of vertebrae. You can think of these intervertebral disks as being like jelly doughnuts. In the middle is a gelatinous material, called the nucleus pulposus, that is surrounded by a fibrous container called the annulus fibrosus. When a disk herniates, a portion of the nucleus pulposus protrudes through its covering. If that material presses on a nearby nerve root or (in rare cases) on the spinal cord itself, it can cause pain and nerve damage. Although severe injuries can cause disks to herniate, more commonly the problem arises from the wear and tear of daily living.

Disk herniations may cause mild to severe pain in the back or neck, muscle spasm, and pain which travels along the course of the nerve root being pinched. Often people feel these symptoms more when they cough, sneeze, or strain.

Most disk herniations occur at the low cervical and low lumbar regions. The problem in the lumbar spine may cause pain to radiate into the buttock and leg (sciatica), or produce numbness or weakness in the leg. If the cauda equina is compressed, a person may suffer bowel and bladder incontinence, leg weakness, sensory loss, and other neurological problems. Sitting may exacerbate the pain of a lumbar disk herniation because that position puts more pressure on the disks than standing or lying down.

Disk herniations in the neck may cause pain that radiates down one arm as far as the hand. If the nerve root is severely compressed, a person may notice arm numbness and weakness. When a herniated disk compresses the spinal cord, the results may be leg weakness, gait difficulties, or bowel and bladder incontinence.

Diagnosis and Treatment

Diagnosis begins with a physician taking a thorough history and conducting a physical examination. Routine X rays of the spine do not show the herniation of a disk but may reveal related problems, such as spondylosis (degenerative disease) and fractures. Magnetic resonance imaging (MRI) and computed tomography (CT) scans may identify the disk herniation and whether it is compressing a nerve root or the spinal cord. Myelography, which requires injecting dye into the spinal canal, is less common since MRI and CT became available.

Neurologists may also conduct electrodiagnostic studies such as EMG (electromyography) to identify damage to the nerve roots. This involves placing a needle in a muscle and measuring the pattern of electrical activity when the muscle is relaxed or contracted. The results help to show if the nerve feeding the muscle has been damaged.

For most people, the symptoms of herniated disks disappear with several weeks of rest and analgesics. In some cases, a supervised exercise and physical therapy program may relieve the acute symptoms and help prevent them from recurring. Pain due to muscle spasm is common, and treatment with ice, heat, massage, stretching, and sometimes traction may be helpful.

A physician may recommend surgery to remove the disk herniation if a person has severe or worsening nerve damage such as weakness or incontinence, or if the pain does not respond to nonsurgical treatments. The surgeon may choose to approach the disk from the back, removing a small piece of bone (laminectomy) and the disk material. Alternatively, the surgeon may choose to approach the disk from the front, especially when it is in the neck; in this case, the doctor often considers fusing the vertebrae on either side of the damaged disk. 

Spondylosis

Spondylosis, also referred to as degenerative joint disease or osteoarthritis, is a condition of normal aging. Cervical and lumbar spondylosis is especially common; nearly all of us have it by late middle age. Bone spurs (osteophytes) form on the edges of the disks and the facet joints where the vertebrae link to each other. These bone spurs commonly result in stiffness, loss of range of motion, and discomfort.

In more severe cases, spondylosis can lead to back and neck pain, muscle spasms or guarding (that is, stiffening of muscles to avoid precipitating pain), and the radiating of pain into extremities. These symptoms are similar to those of disk herniation, but they tend to be less acutely severe and more chronic and intermittent. Spondylosis and disk herniation may also occur together and both may contribute to a person’s difficulties.

If bone spurs form between vertebrae, they can irritate the adjacent nerve roots, producing such symptoms as pain in a limb and, less often, loss of sensation or weakness in the area served by that nerve root. If a bone spur forms in the spinal canal, the result can be cervical spondylotic myelopathy or spinal stenosis.

Diagnosis and Treatment

Physicians start with a thorough medical and neurological history and examination while considering other diseases that can mimic spondylosis. Imaging the spine with X rays, CT, or MRI may identify bone spurs and whether they are likely to be compressing nerves. Discomfort from spondylosis usually responds to rest, analgesics such as aspirin, and nonsteroidal anti-inflammatory agents. A physician may also recommend physical therapy and an exercise program of stretching and strengthening. If there is severe nerve or spinal cord compression, however, the doctor may recommend surgery.

Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy refers to a condition in which spondylosis leads to compression of the spinal cord itself. Usually the first symptom is discomfort in the neck or shoulders and arms over a number of months or years, followed by problems with walking and running, weakness or sensory loss in the legs, or bowel and bladder difficulties. Symptoms may be intermittent over many years or become steadily worse. A person may develop dulled reflexes in the arms when the nerve roots are compressed and spastic “jumping legs” because the compression interferes with the inhibitory impulses from the brain to the legs.

Diagnosis and Treatment

Doctors do a neurological examination, looking for these hypoactive and hyperactive reflexes and other symptoms and signs. They may also test for the Babinski sign: stroking the sole of the foot and watching for an upward movement of the big toe. Diagnosis is usually confirmed by MRI, which can show the offending osteophyte(s) and disk material as well as the spinal cord and nerve roots. If the spinal cord is significantly compressed, the MRI may even show it as distorted.

At the same time, physicians consider many neurological diseases with similar symptoms, such as multiple sclerosis, vitamin B12 deficiency, amyotrophic lateral sclerosis, brain tumors, inherited and degenerative diseases of the nervous system, and syringomyelia.

Managing cervical spondylotic myelopathy depends on an individual’s particular condition, but in general it includes both surgical and nonsurgical treatments. In some people whose neurological deficits are mild and not worsening, physicians may recommend rest, a collar to stabilize the neck, and neck-strengthening exercises. These individuals are usually followed closely by their doctors in order to identify any changes.

Alternatively, the patient and physician may decide that the best course is surgery to decompress the spinal cord. There are several different procedures possible. These include approaching the spinal area from the front or the rear and spinal fusion. Selecting the most appropriate operation is important.

Lumbar Spinal Stenosis

In lumbar spinal stenosis, a person’s lumbar spinal canal becomes narrowed, usually because of bone spurs and sometimes because of disk herniation as well. The initial symptoms are therefore similar to those described above. If the stenosis becomes severe, however, the nerves of the cauda equina may be compressed. This condition is most likely to occur in individuals who are born with a narrow spinal canal and develop spondylosis later in life. 

The symptoms of lumbar spinal stenosis are sometimes called neurogenic claudication. They include difficulty in walking, which develops gradually but becomes apparent after an individual has gone some distance. Commonly the signs are discomfort in the back and legs and numbness and tingling in the legs, which gets worse the longer one walks. As the condition progresses, the distance one can walk comfortably diminishes. Characteristically, a person’s symptoms improve if he or she bends forward; in this position the spinal canal becomes wider, reducing the nerve root compression. Thus, a person may be able to walk much farther leaning on a shopping cart than walking upright. In advanced cases, people develop symptoms from simply standing for extended periods.

Diagnosis and Treatment

Physicians usually diagnose lumbar spinal stenosis using MRI and CT scanning. Electrodiagnostic studies such as EMG may help identify damaged nerve roots that are causing weakness in the lower extremities. Neurogenic claudication must be distinguished, however, from claudication due to diminished blood circulation to the legs.

In some cases, neurogenic claudication from lumbar spinal stenosis may be alleviated by surgery to stop the nerve compression. If it is decided that the risk of an operation outweighs the possible benefits, doctors may prescribe anti-inflammatory agents, encourage weight loss, and recommend an exercise and conditioning program.  

back to top