Diagnostic Tests

A Patient's Guide to Diagnostic Tests for Spine Problems

History

Before a health care professional can diagnose your condition and design a treatment plan, a complete history and physical examination are necessary. There are so many possible internal causes of pain; it is important to determine what is and is not causing the problem. After the physician has a better idea of what is causing your discomfort, diagnostic tests of may be recommended.

First, you will be asked for a complete physical history of your condition. This may begin by filling out a written form that asks you a number of questions relating to your pain. The more information you share with the provider, the easier your problem will be to diagnose. Your physical history is important because it helps your doctor understand: when the pain began, anything that could have caused an injury, your lifestyle, physical factors that might be causing the pain, and your family history of similar problems. After reading through your written history, your physician will ask more questions that relate to the information you have given. Some typical questions include:

  • When did the pain begin?

  • Was there an injury that could be related to the pain?

  • Where do you feel the pain? What is the intensity?

  • Does the pain radiate to other parts of the body?

  • What factors make the pain feel better or worse?

  • Have you had problems with your bladder or bowels?

  • Is there a history of osteoporosis in your family?

Physical Examination

After taking your history, the physician will give you a physical examination. This allows the doctor to rule out possible causes of pain and try to determine the source of your problem. The areas of your body that will be examined depend upon where you are experiencing pain - neck, lower back, arms, legs, etc. The following are some of the things that are checked in a typical exam:

  • Motion of Spine and Neck - Is there pain when you twist, bend, or move? If so, where? Have you lost some flexibility?

  • Weakness - Your muscles will be tested for strength. You might be asked to try to push or lift your arm, hand, or leg when light resistance is put against them.

  • Pain - The doctor may try to determine if you have tenderness of certain areas.

  • Sensory Changes - Can you feel certain sensations in specific areas of the feet or hands?

  • Reflex changes - Your tendon reflexes might be tested, such as under the kneecap and under the Achilles tendon on your ankle.

  • Motor skills - You might be asked to do a toe or heel walk.

  • Special signs - The physician will also check for any "red flags" that could indicate something other than spinal/vertebrae problems. Some signs of other problems include tenderness in certain areas, a fever, an abnormal pulse, chronic steroid use (leads to loss of bone mass), or rapid weight loss.

Diagnostic Tests

You may be asked to take a variety of diagnostic tests. The tests are chosen based upon what your physician suspects is the cause of your pain. These are the most common diagnostic tests:

X-rays

An X-ray is a painless process that uses radioactive materials to take pictures of bone. If your doctor suspects vertebral degeneration, X-rays can be used to verify a decrease in the height of space between discs, bone spurs, nerve bundle sclerosis (hardening), facet hypertrophy (enlargement), and instability during flexion or extension of limbs. X-rays show bones, but not much soft tissue, so they will definitely be used if fractures, infections, or tumors are suspected.

During X-rays, you will be asked to lie very still on a table and hold certain positions while photographs are taken of your spine.

MRI Scan (Magnetic Resonance Imaging)

The MRI scan is a fairly new test that does not use radiation. By using magnetic and radio waves, the MRI creates computer-generated images. The MRI is able to cut through multiple layers of the spine and show any abnormality of soft tissues, such as nerves and ligaments. The test also can be used to verify loss of water in a disc, facet joint hypertrophy (enlargement), stenosis (narrowing of spinal canal), or a herniated disc (protrusion or rupture of the intervertebral disc).

During an MRI test, you lie on a table that slides into a machine with a large, round tunnel. The machine's scanner then takes many pictures that are watched and monitored by a technician. Some newer MRI machines, called OPEN MRIs, are likely to be more comfortable for patients who experience claustrophobia. The procedure takes 30-60 minutes.

CAT Scans (Computer Assisted Tomography)

The CAT scan is an X-ray test that is similar to both the MRI and a regular X-ray, because it can show both bones and soft tissues. CAT scans are also able to produce X-ray "slices" taken of the spine, allowing each section to be examined separately. The scan forms a set of cross-sectional images that can show disc problems and degeneration of bones, such as bone spur formation or facet hypertrophy (enlargement). CAT scan images are not as clear as either X-rays or an MRI. To make the soft tissues easier to see, the CAT scan it is often combined with a myelogram.

Like an MRI, with a CAT scan you will lie on a table that slides into a scanner. The scanner is essentially an X-ray tube that rotates in a circle taking many pictures. The procedure takes 30-60 minutes.  

Myelogram

A myelogram is an older test that is used to examine the spinal canal and spinal cord. During this test, a special X-ray dye is placed into the spinal sac. This will require a spinal tap to be performed by your doctor. This procedure is performed by inserting a small needle in the lower back and into the spinal canal. Through the needle, dye is injected which mixes with the spinal fluid.
The dye shows up on X-rays. Therefore, when the X-ray is taken, the dye outlines the spinal cord and nerve roots so that disc and bone spur problems can be seen.

To conduct the myelogram, the patient lies on a tilting table. As the table tilts, the movement of the dye shows the outline of the spinal sac. X-rays are taken as the patient is titled to show the flow of the dye through the spinal region, helping doctors determine if there is any unusual indentation or an abnormal shape. This indentation could be from a herniated or bulging disc, lesions, tumors, or injury to the spinal nerve roots. The myelogram is often combined with a CAT scan to get a better view of the spine in cross section.

In many cases, the MRI has replaced both the myelogram and the CAT scan. Sometimes the myelogram still shows the problem better than the MRI, but today it is used less frequently than the MRI. 

Bone Scan

A bone scan can be used to locate the problem area of the spine. The bone scan works by injecting a radioactive chemical, sometimes called a "tracer", into the bloodstream through an IV. The chemical will attach itself to any areas of bone that are undergoing rapid changes. A special camera takes pictures of the area of the skeleton where the problem lies.

Problem areas will show up as dark areas on the film. This is because the chemical tracer travels to spot where the problem lies. Over a period of several hours, a lot of the tracer accumulates in the area. The chemical tracer is radioactive, and therefore sends out radiation that can be captured by the camera. The film produced by the camera identifies the "hotspots" or specific problem areas.

A bone scan is very useful when it is unclear exactly where the problem is in the skeleton. The ability to take a picture that lights up the area where the problem seems to be coming from allows the doctor to pinpoint where to look next. After locating the problem areas, other tests can be done to show more aspects of those specific spots. The bone scan can identify problem areas such as bone tumors and compression fractures. A bone scan can also be used to determine bone density and the bone-thinning condition of osteoporosis.

EMG/SSP (Electrodiagnostic Study)

An electromyogram (EMG) is a test that looks at the function of the nerve roots leaving the spine. The test is done by inserting tiny electrodes into the muscles of the lower extremity. By looking for abnormal electrical signals in the muscles, the EMG can show if a nerve is being irritated, or pinched as it leaves the spine. Think of how you test the wiring on a lamp. If you place a working bulb into the lamp, and the bulb lights up, you assume that the wiring is okay. However, what if the bulb does not light up? You can safely assume that something is probably wrong with the wiring, like the lamp is unplugged, or a short circuit has occurred. By using the muscles like the light bulb in the lamp, the EMG is able to determine the condition of the nerves that supply those muscles, like the wiring on the lamp. If the EMG machine finds that the muscles (the light bulb) are not working properly, the doctor can assume that the nerves (the wiring) must be getting pinched somewhere.

Facet Joint Block

Like any joint in the body, facet joints can cause pain if they are irritated or inflamed. The facet joint block is a procedure where a local anesthetic medication (such as lidocaine or Novocain) is injected into the facet joint. This same type of medication is used by a dentist to numb your jaw, or a doctor to sew up a laceration. The lidocaine actually numbs the area around the facet joint. If all your pain goes away, the doctor can assume that the facet joint is a problem.

Laboratory Tests

Further lab tests may be done to check for problems that are not related to deterioration of the spine. Other testing can help determine the presence of serious problems such as: an infection, arthritis, cancer, or an aortic aneurysm. The most frequent lab test is blood sampling.

Spinal Tap

A spinal tap is done in order to get a sample of the cerebrospinal fluid that surrounds the spinal cord. The fluid is usually very clear. It contains proteins, sugar, and other substances that can be found in blood. It typically does not contain red blood cells or many white blood cells. A spinal tap checks the pressure and content of the fluid. Signals that there may be problems include: evidence of bleeding, an increase in white blood cells (infection fighting cells, dead cells are "pus"), an increase in protein level, or inflammation. This could mean infection, tumors, or a hemorrhage around the brain or spinal cord. To obtain the fluid sample, a needle will be inserted into the spinal canal in the lumbar region.

Discogram

A discogram is an X-ray examination of the intervertebral discs. This test is used to determine which disc(s) are damaged and if surgery is necessary. The test is performed by injecting dye into the center of the injured disc(s). The dye makes the disc clearly visible on X-ray film and a fluoroscope screen. This test is better than an X-ray or myelogram for determining if there is a disc problem. The dye helps the physician make an accurate diagnosis. A simple X-ray shows only the vertebrae, and a myelogram is best for assessing the spinal canal.

With a discogram, you will be given medication to help you relax, then a local anesthetic. The procedure usually lasts about 40 minutes.

This page was last updated: July 3, 2013

         
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