Herniated disc diagnosis begins with a complete history and physical exam. The doctor will ask questions about symptoms and how the problem is affecting daily activities. Questions about pain location and whether there is numbness or weakness in the legs. The doctor will also want to know what positions or activities make symptoms worse or better.
Then the doctor physically examines to determine which back movements cause pain or other symptoms. Skin sensation, muscle strength, and reflexes are also tested.
X-rays are of minor help in diagnosing a herniated disc. The discs don’t show up on X-rays. However, doctors can tell if the space between the vertebrae is smaller than normal. This can be an indication that wear and tear on one or more discs is causing problems. Many peoples’ X-rays show degeneration of the discs due to normal aging. The question is whether there is more than normal degeneration due to work-related activities.
A CT scan may be ordered, a detailed X-ray that lets doctors see slices of the body’s tissue. The image can show if a herniated disc is putting pressure on a spinal nerve.
Doctors may combine the CT scan with myelography. To do this, a special dye is injected into the space around the spinal canal, called the subarachnoid space. When the CT scan is performed, the dye highlights the spinal cord and nerves. The dye can improve the accuracy of a standard CT scan for diagnosing a herniated disc.
Finally, if disc herniation is suspected, the doctor may order magnetic resonance imaging (MRI). The MRI machine uses magnetic waves rather than X-rays to show the soft tissues of the body. It gives a clear picture of the discs and whether a herniation is present. Like the CT scan, this machine creates pictures that look like slices of the area your doctor is interested in. The test does not require special dye or a needle.
Doctors sometimes order a specialized X-ray test called discography. In this test, dye is injected into one or more discs. The dye is seen on X-ray and can give some information about the health of one or more discs. This test may be used when surgery is being considered to determine which disc is causing problems.
Doctors may also order electrical tests to locate more precisely which spinal nerve is being squeezed. Several tests are available to see how well the nerves are functioning, including the electromyography (EMG) test. This test measures how long it takes a muscle to work once a nerve signals it to move. The time it takes will be slower if a herniated disc has put pressure on a spinal nerve.
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