Myelopathy

What Is Myelopathy?

The word myelopathy (my-uh-LOP-uh-thee) comes from the prefix myelo–, meaning “spinal cord,” plus the suffix –pathy, meaning “suffering.” Sometimes myelopathy is confused with radiculopathy.

Here’s the difference: Myelopathy is spinal cord compression, whereas radiculopathy is compression of spinal nerves. It’s also easy to confuse myelopathy with myopathy. The prefix myo– comes from the Greek word myos, meaning “muscle.” Myopathies, then, are muscular disorders, not spinal cord disorders.

xray image of spinal cord — Image courtesy Bruce Blausen, Wikimedia Commons.

Myelopathy is compression of the spinal cord. It causes pain, impairs normal functioning, and puts patients at a high risk of disability. The underlying conditions that cause myelopathy tend to get worse if left untreated. In turn, neurologic (nervous system) functioning continues to deteriorate as the spinal cord becomes more and more compressed. Thus, doctors categorize myelopathy as a progressive disorder. In fact, many physicians have begun to call the disease degenerative cervical myelopathy (DCM).

Types of Myelopathy

Myelopathy can be categorized according to the location of the spinal cord compression:

Lumbar Myelopathy: In most people, the spinal cord ends just above the lumbar spine (see diagram). Thus, lumbar myelopathy is rare and occurs only in those with unusual spinal anatomy.
Thoracic Myelopathy: Myelopathy affecting the spine at the thoracic (mid-back) level is possible, but it’s much less common than cervical myelopathy.
Cervical Myelopathy: Cervical myelopathy refers to spinal cord compression at the level of the cervical spine.

How Common Is Myelopathy?

Cervical myelopathy affects perhaps 5% of adults age 40 and over. In those age 55 and older, most cervical myelopathy is attributable to spondylosis. As the U.S. population ages, myelopathy and surgical correction of myelopathy have both become more common. This trend is expected to continue.

Myelopathy Symptoms

Myelopathy causes clumsiness and gait disturbances (such as stiffness, unsteadiness, or a change in the rhythm or speed of walking). In a small study of patients with cervical myelopathy, 100% of study participants (22 patients) reported that this nonspecific gait change was their earliest symptom.

Myelopathy impairs normal functioning, making it a chore to do such things as button your shirt, pick up a cup of coffee, or eat a bowl of soup. You may lose sensation in your arms, legs, or hands. Your legs may feel weak, and you might lose your balance or drop things more often than you used to. You might lose manual dexterity and have difficulty writing or combing your hair.

Other symptoms include spasticity of the arms or legs, neck or shoulder pain, occasional bladder incontinence (because nerves branching off the spinal cord send faulty signals to the bladder), and sensory abnormalities such as blurred vision, tinnitus (ringing in the ears), and dysphagia (difficulty swallowing).

Sometimes patients with nonspecific symptoms like these are told that they’re just stressed out or getting older. Changes in gait or balance, in particular, are often attributed to the aging process and thought to be healthy. Trouble with your arms or hands may be misdiagnosed as carpal tunnel syndrome—failure to recognize these subtle symptoms as evidence of myelopathy delays diagnosis by six years on average.

Myelopathy Causes

Myelopathy has a broad range of causes, from congenital disorders to degenerative processes and acute conditions.

Congenital Causes of Myelopathy
Certain congenital disorders, such as hypoplasia of the atlas (underdevelopment of the first cervical vertebra) can cause myelopathy or predispose a person to developing it. For example, some people are born with unusually narrow spinal canals (see Stenosis).

Degenerative Processes
Myelopathy can develop as we age. For some patients, the condition takes hold rapidly and leads quickly to disability. For others, it produces steadily declining functioning and gradually increasing pain throughout years, as with, say, spinal arthritis.

For most patients, however, the disease proceeds in a sort of “one step forward, two steps back” fashion. Symptom flare-ups follow periods during which there is no decline. Sometimes a minor trauma, such as a fall, exacerbates symptoms. These periods of equilibrium don’t represent remission of the disease, however. After each flare-up, the patient returns to a new, diminished level of functioning.

Spondylosis
Spondylosis is the leading cause of cervical myelopathy. For that reason, the condition is often called cervical spondylotic myelopathy (CSM). Spondylosis involves a complex series of age-related changes: degenerative disc disease, the collapse of the disc space, formation of bone spurs within this space, and calcification of key ligaments and other surrounding structures. These changes predispose a person to developing myelopathy.

Herniated Disc
When a disc herniates, its contents are usually expelled to the side, where nerves enter and exit the spinal column. Sometimes, however, a disc herniates straight backward, expelling the nucleus into the spinal canal and putting pressure on the spinal cord. This is called central disc herniation.

Spinal Stenosis
The average spinal canal is 17 to 18 mm in diameter—about the same as the diameter of a U.S. dime. Spinal stenosis is a condition in which the diameter of the spinal canal narrows or a person is born with a narrow canal.

A diameter of less than 12 mm leaves little room for anything to go wrong. Degenerative changes become problematic more quickly than they would in a patient whose spinal canal is of normal proportions.

Acute Causes of Myelopathy

Injury
Injury to the spinal cord can cause myelopathy. The cord can sustain a traumatic injury, such as a fall, or it can be injured in other ways. For example, the cord might be compromised when radiation is applied to a tumor in the area.

Infection
Infection of the spinal cord (for example, with tuberculosis) can cause myelopathy. Cytomegalovirus infection of the spinal cord, a neurologic complication of AIDS, can cause spasticity, weakness, and loss of sensation in the extremities.

Disease Processes
Various disease processes are associated with spinal cord compression. In people with multiple sclerosis, myelopathy can cause difficulty walking. Autoimmune conditions like rheumatoid arthritis can affect the bones and joints of the spinal column, compressing the spinal cord and causing myelopathy.

Other Causes of Myelopathy
Any mass that takes up residence in the spinal column can encroach on the spinal cord. For example, a blood clot can lodge in the spinal canal, or a tumor, cyst, or osteophyte (bone spur) can grow there.

How Myelopathy Is Diagnosed

Early diagnosis of myelopathy increases the likelihood of a good outcome and reduces the risk of permanent disability. Diagnosing back pain always requires some detective work, but recognizing myelopathy is especially challenging. That’s because it produces vague, puzzling, seemingly unrelated symptoms that can throw off even an astute clinician.

For example, one symptom of cervical myelopathy is urinary urgency, frequency, or hesitancy. Hearing this complaint, a doctor might refer the patient to a urologist or simply advise him or her to cut back on his or her coffee or soda intake.

To make an accurate diagnosis, your doctor will need to gather information from many different sources. He or she will ask when and how your walking difficulties began, whether the trouble is constant or intermittent, and how intense your pain is. Your physician or surgeon will also ask about your general health and lifestyle habits.

The doctor may also want to perform imaging studies, such as an MRI scan, which can reveal spinal cord compression and associated stenosis, spondylosis, disc degeneration, or disc herniation. Electromyography (EMG) may be needed to rule out conditions that can mimic myelopathy, such as amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease) and multiple sclerosis (MS).

Conservative Myelopathy Treatments

Treatment of myelopathy is aimed at improving mobility, restoring fine motor skills, reducing pain, and preventing progression of the disorder. Before deciding on a specific treatment, your doctor will explain your options. Be sure to ask questions if anything is unclear.

Non-Surgical Myelopathy Treatments

Your doctor will probably begin with conservative treatment options, such as:

NSAIDs (nonsteroidal anti-inflammatory medications)
Physical or occupational therapy
You may be fitted with a special collar or brace

If your condition is mild or you’re still relatively young or both, such measures can decrease your pain and improve your neurologic functioning so you can return to normal activities.

Myelopathy Surgery: What are Your Options?

Conservative measures might delay the need for surgery, but remember: Myelopathy is a progressive disorder. Studies show that patients over age 60 and those with significant impairment or dysfunction who have surgery have better results than those who opt for nonsurgical treatment.

The surgical treatment of myelopathy is called spinal decompression surgery. Decompression is generally recommended for those who are already severely disabled when myelopathy is diagnosed.

Fortunately, studies have shown that both younger and older patients benefit significantly from surgical decompression surgery. Older patients have a slightly higher rate of complications, but their likelihood of functional improvement and symptom relief is as high as that of younger patients.

Minimally Invasive Myelopathy Surgery

The less invasive the surgical approach is, the lower the rate of complications. Open surgical procedures have the highest complication rate, and minimally invasive procedures have the lowest.

Minimally invasive spinal surgery requires a much smaller incision and can be performed quickly, which reduces risks associated with being under anesthesia. Even patients who smoke and those with obesity who may be poor candidates for open surgical procedures may still be eligible for minimally invasive spinal surgery.

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