TECHNIQUES FOR DIAGNOSING THE OFTEN ELUSIVE CAUSES OF BACK PAIN

Persistent or serious back pain will often motivate your doctor to order one or more imaging studies to pinpoint or confirm the cause of the pain. Each of these studies has benefits and limitations, but provide a view of the bones and the soft tissues (muscles, ligaments, cartilage, tendons, and blood vessels) that is especially important if the possibility of surgery looms. Read on for a comparison of the various studies available.

X-RAYS
Your doctor will probably opt for x-rays as the first imaging study for chronic back pain and for new-onset back pain lasting longer than four to six weeks. They are especially useful for detecting fractures and invasion of bone by multiple myeloma (tumors of the bone marrow). People over age 50 are more likely to need spinal x-rays because these individuals have a greater risk of malignancy and vertebral fractures. People should not be concerned about the possible risks of modern x-rays; the radiation doses are low and there is no evidence of harm even from repeated x-rays. Conventional x-rays are available almost anywhere and are relatively low in cost ($150 to $200).

COMPUTED TOMOGRAPHY (CT) SCANS
A CT scan, also called a computerized axial tomography (CAT) scan, involves a series of x-rays that are taken as a special detector rotates 360° around the patient. A computer combines all the information into a cross-sectional picture. CT scans, 10 to 20 times more sensitive than x-rays, provide better soft-tissue detail and good detail of the vertebrae. Although MRI scans or CT myelograms (see below) are even more useful for examining the soft tissues (for example, herniated disks), CT scans are still best for studying bone problems — for example, bone destruction due to infection. CT scans are considerably more expensive and deliver more radiation than conventional x-rays (approximately $550).

CT MYELOGRAM
A CT myelogram involves a CT scan after the injection of a contrast material into the spinal canal. The injection carries the risk of infection and such side effects as nausea, headaches, and pain or discomfort at the site of injection. In addition, a person is required to sit or lie with the head elevated for six to eight hours afterward. These scans offer the best detail of bone and soft tissue. CT myelograms are usually performed only prior to surgery or after failed surgery (about $600).

MAGNETIC RESONANCE IMAGING (MRI)
In MRI, the most sensitive imaging technique, the patient is surrounded with a powerful magnet while radio waves are passed through the body. No x-rays are involved. This test provides the best images of soft tissues and is completely safe. However, MRI may not give a useful image of the bones in the spine. MRI is not recommended for early diagnosis of back pain unless the doctor suspects a serious condition, such as cauda equina syndrome (pressure on the nerve bundle that ends near the first lumbar vertebra; can have any number of causes and may cause serious and/or permanent nerve damage). Despite their sensitivity, studies have shown that MRIs should be reserved for preoperative evaluation or for people with a suspected herniated disk whose back pain symptoms do not respond to conservative treatment after four to six weeks.

MRI commonly visualizes disk abnormalities. In one study, at least one disk was affected in 64 percent of people who had no back pain. Disk herniation was present in 27 percent of these subjects (this number increased with age). Thus, the abnormalities revealed by an MRI are not necessarily the cause of a person’s back pain. In addition, this technique is costly, and MRI devices are not available everywhere.

Because people must lie perfectly still for between 30 minutes and two hours in a relatively small space, MRIs may be uncomfortable and poorly tolerated by those who are claustrophobic. (Open MRIs produce less claustrophobia but generally do not provide high-quality views and are not recommended.) In addition, depending on which part of the spine requires the MRI, it usually cannot be used in people with intrauterine devices, metal joint replacements, aneurysm clips, implantable cardioverter-defibrillators, or pacemakers (about $1,000).

BONE SCANS
Bone scans measure the amount of radioactivity emitted from bone after the injection of a bone-seeking compound that contains technetium, a radioactive metal. The bone is scanned two to three hours after the injection, and information about the distribution of the radioactive compound in the bone is fed to a computer, which produces a two-dimensional image of the bone. An area of bone that displays an increased uptake of technetium has a higher rate of bone turnover, which can be the result of a fracture not identified on an x-ray as well as metastatic cancer, Paget’s disease, or osteomyelitis (a bacterial infection of the spine). The amount of radiation delivered is similar to that of a CT scan. This technique can be used to identify fractures in both the central and peripheral areas of the body (about $500).

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Disclaimer: The purpose of this weblog is not to dispense medical advice nor in any way is meant to be construed as diagnostic or prescriptive. Always check with your physician before beginning any new program or trying any of the items discussed in the posts that appear on this site.

Comments

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[Acupuncture Services]

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