Cause of Back Pain and MRI as a Diagnostic Tool

The back and spine are designed to provide a great deal of strength, protecting the highly sensitive spinal cord and nerve roots, yet flexible, providing for mobility in all directions. However, there are many different parts of the spine that can produce back pain, such as irritation to the large nerve roots that run down the legs and arms, irritation to small nerves inside the spine, strains to the large back muscles, as well as any injury to the disc, bones, joints or ligaments in the spine.

Because the causes of back pain are often complex and multi-factorial, it is often more difficult to get an accurate diagnosis for back pain than for other medical conditions. While some spinal diagnoses are relatively straightforward (such as tumors, infections, or fractures), for many conditions there is little agreement among spine specialists about a diagnosis.

The challenge for healthcare providers is to diagnose the correct disease so they can recommend the appropriate treatment. While there are a number of diagnostic imaging tests physicians can use to determine the cause of a patient’s pain—CT scans, MRIs, nuclear imaging studies—choosing the most appropriate test is not always a straightforward decision, and experts often disagree on the best course of action.

Diagnostic Process

The medical diagnosis, also called a clinical diagnosis, serves to identify the underlying cause of the patient’s back pain. Medical professionals determine the cause of the patient’s pain through a combination of the following two to three steps:

A Review of the Patient’s Medical history

The physician will spend time asking the patient a series of questions, such as a description of when the low back pain, sciatica, or other symptoms occur, a description of how the pain feels, what activities, positions, or treatments make the pain feel better and more.

A Physical Examination

The physicians will conduct a thorough physical exam of the patient, such as testing nerve function and muscle strength in certain parts of the leg or arm, testing for pain in certain positions, and more. Usually, this series of physical tests will give the spine professional a good idea of the type of back problem the patient has.

Diagnostic Testing (Maybe)

After the physician has a good idea of the source of the patient’s pain, a diagnostic test, such as a CT scan or an MRI scan, may be recommended in order to confirm the presence of the suspected cause of the patient’s pain. For example, if a disc problem is suspected, an imaging test can provided a detailed image showing the location and size of the herniated disc and affected nerve roots.

Should You Have an MRI for Your Back Pain?

MRIs are powerful but can lead doctors on a wild goose chase. At what point should your doctor take a look inside your back with a high-tech MRI or CT scan, or even an old-fashioned X-ray? In most cases, the answer is later rather than sooner.

The rap against MRIs as a diagnostic tool for low back pain is not that the scans usually reveal nothing, or even that they’re expensive, it’s that they often show a lot of abnormalities in the back that may have nothing to do with the source of your pain. With aging, the hard-working spine begins to show signs of wear and tear, such as degeneration of disks and arthritis in joints. But for a pain condition that in most cases resolves itself in less than two months without dramatic intervention, that kind of information isn’t particularly helpful.

MRIs do not expose your body to radiation. But CT scans and X-rays do, which make them especially risky for women with lower back pain who are in their childbearing years.

When do imaging tests make sense?

It can be a good idea to get an imaging test right away if you have signs of severe or worsening nerve damage, or a serious underlying problem such as cancer or a spinal infection. “Red flags” that can alert your doctor that imaging may be worthwhile include:

• A history of cancer.
• Unexplained weight loss.
• Fever.
• Recent infection.
• Loss of bowel or bladder control.
• Abnormal reflexes, or loss of muscle power or feeling in the legs.

Your doctor might recommend an MRI if he or she suspects that your low back pain is caused by something more serious than muscle strain. This may be the case if:

• Your history and physical examination show signs of a serious problem, such as a fracture, tumor’s, infection, or nerve damage.
• You are older than 70. Your doctor may also recommend testing if you are older than 50 and also have osteoporosis or a history of compression fracture.
• You have had osteoporosis for a long time or you have diabetes.
• Your body’s defense system (immune system) is not able to fight infection.
• You have a history of long-term steroid use or a history of a drug problem.
• You have a history of a previous spine injury or back surgery.
• You have symptoms related to compression on a certain nerve root or roots.
• Back pain has not improved after at least 6 weeks of home treatment that may include pain relievers, heat or ice, and exercises.

The information in this document does not replace a medical consultation. It is for personal guidance use only. We recommend that patients ask their doctors about what tests or types of treatments are needed for their condition.