Published on June 3, 2009

What Are the Causes of Back Pain?

It is important to understand that back pain is a symptom of a medical condition, not a diagnosis itself. Medical problems that can cause back pain include the following:

Mechanical problems: A mechanical problem is a problem with the way your spine moves or the way you feel when you move your spine in certain ways. Perhaps the most common mechanical cause of back pain is a condition called intervertebral disc degeneration, which simply means that the discs located between the vertebrae of the spine are breaking down with age. As they deteriorate, they lose their cushioning ability. This problem can lead to pain if the back is stressed. Other mechanical causes of back pain include spasms, muscle tension, and ruptured discs, which are also called herniated discs.

Injuries: Spine injuries such as sprains and fractures can cause either short-lived or chronic pain. Sprains are tears in the ligaments that support the spine, and they can occur from twisting or lifting improperly. Fractured vertebrae are often the result of osteoporosis, a condition that causes weak, porous bones. Less commonly, back pain may be caused by more severe injuries that result from accidents or falls.

Acquired conditions and diseases: Many medical problems can cause or contribute to back pain. They include scoliosis, which causes curvature of the spine and does not usually cause pain until middle age; spondylolisthesis; various forms of arthritis, including osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis; and spinal stenosis, a narrowing of the spinal column that puts pressure on the spinal cord and nerves. Although osteoporosis itself is not painful, it can lead to painful fractures of the vertebrae. Other causes of back pain include pregnancy; kidney stones or infections; endometriosis, which is the buildup of uterine tissue in places outside the uterus; and fibromyalgia, which causes fatigue and widespread muscle pain.

Infections and tumors: Although they are not common causes of back pain, infections can cause pain when they involve the vertebrae, a condition called osteomyelitis, or when they involve the discs that cushion the vertebrae, which is called discitis. Tumors also are relatively rare causes of back pain. Occasionally, tumors begin in the back, but more often they appear in the back as a result of cancer that has spread from elsewhere in the body.

Although the causes of back pain are usually physical, emotional stress can play a role in how severe pain is and how long it lasts. Stress can affect the body in many ways, including causing back muscles to become tense and painful.

How Is Back Pain Diagnosed?

Diagnosing the cause of back pain requires a medical history and a physical exam. If necessary, your doctor may also order medical tests, which may include x rays.

During the medical history, your doctor will ask questions about the nature of your pain and about any health problems you and close family members have or have had. Questions might include the following:

• Have you fallen or injured your back recently?
• Does your back feel better – or hurt worse – when you lie down?
• Are there any activities or positions that ease or aggravate pain?
• Is your pain worse or better at a certain time of day?
• Do you or any family members have arthritis or other diseases that might affect the spine?
• Have you had back surgery or back pain before?
• Do you have pain, numbness, or tingling down one or both legs?

During the physical exam, your doctor may:

• watch you stand and walk
• check your reflexes to look for slowed or heightened reflexes, either of which might suggest nerve problems
• check for fibromyalgia by examining your back for tender points, which are points on the body that are painful when pressure is applied to them
• check for muscle strength and sensation
• check for signs of nerve root irritation.

Often a doctor can find the cause of your pain with a physical and medical history alone. However, depending on what the history and exam show, your doctor may order medical tests to help find the cause.

Following are some tests your doctor may order:

X rays: Traditional x rays use low levels of radiation to project a picture onto a piece of film (some newer x rays use electronic imaging techniques). They are often used to view the bones and bony structures in the body. Your doctor may order an x ray if he or she suspects that you have a fracture or osteoarthritis, or that your spine is not aligned properly.

Magnetic resonance imaging (MRI): MRI uses a strong magnetic force instead of radiation to create an image. Unlike an x ray, which shows only bony structures, an MRI scan produces clear pictures of soft tissues, too, such as ligaments, tendons, and blood vessels. Your doctor may order an MRI scan if he or she suspects a problem such as an infection, tumor, inflammation, or pressure on a nerve. An MRI scan, in most instances, is not necessary during the early phases of low back pain unless your doctor identifies certain "red flags" in your history and physical exam. An MRI scan is needed if the pain persists more than 3 to 6 weeks or if your doctor feels there may be a need for surgical consultation. Because most low back pain goes away on its own, getting an MRI scan too early may sometimes create confusion for the patient and the doctor.

Computed tomography (CT) scan: A CT scan allows your doctor to see spinal structures that cannot be seen on traditional x rays. A computer creates a three-dimensional image from a series of two-dimensional pictures that it takes of your back. Your doctor may order a CT scan to look for problems including herniated discs, tumors, or spinal stenosis.

Blood tests: Although blood tests are not used generally in diagnosing the cause of back pain, your doctor may order them in some cases. Blood tests that might be used include the following:

Complete blood count (CBC), which could point to problems such as infection or inflammation

Erythrocyte sedimentation rate (also called sed rate), a measure of inflammation that may suggest infection. The presence of inflammation may also suggest some forms of arthritis or, in rare cases, a tumor.

It is important to understand that medical tests alone may not diagnose the cause of back pain. In fact, experts say that up to 90 percent of all MRI scans of the spine show some type of abnormality, and sometimes the x rays and CT scans of people without pain show problems. Similarly, even some healthy pain-free people can have elevated sed rates.

Only with a medical history and exam - and sometimes medical tests - can a doctor diagnose the cause of back pain. Many times, the precise cause of back pain is never known. In these cases, it may be comforting to know that most back pain gets better whether or not you find out what is causing it.

Note: This material is provided for information purposes only. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.