Initial examination

Your health professional will evaluate your symptoms of leg and back pain using a medical history and physical examination. Your diagnosis will be based on any features that point to irritation of one or more spinal nerves and to the loss of strength, sensation, or reflexes that are normally associated with the nerve or nerves. If your medical history and physical examination suggest you have a herniated disc, you will probably not need additional tests during your first medical visit.

Follow-up tests sometimes used

Imaging tests may help confirm a diagnosis of a herniated disc or may be needed when nonsurgical treatment has not worked to relieve pain. If you still have symptoms after 4 weeks of nonsurgical treatment, your doctor may recommend imaging tests. If the results of an imaging test are not expected to change a treatment decision, the test is probably not needed.

• Magnetic resonance imaging (MRI) may be done to confirm a diagnosis as well as the location and severity of a herniated disc or to look for another serious condition, such as an infection or tumor. An MRI provides detailed images of the soft tissues of the spine, such as the muscles, spinal nerves, tendons, ligaments, discs, and the softer inner part (marrow) of the bones of the spine.³
• Computed tomography (CT) scan may be done to help confirm a diagnosis as well as the location and severity of a herniated disc and to look for any other problems in the bones of the spine. A CT scan can provide detailed images of bony structures of the spine.

An MRI is generally preferred over a CT scan for diagnosing a suspected herniated disc in the lower back (lumbar spine).

X-rays generally are not useful or needed for diagnosing a herniated disc.³ However, if your medical history and physical exam suggest a more serious underlying condition (such as a tumor, infection, fracture, or severe nerve damage), or if your leg pain and other symptoms do not get better after 4 weeks of nonsurgical treatment, your health professional may order X-rays. Other tests, such as blood tests, may be done to rule out other conditions.

Follow-up tests occasionally used

The following imaging tests are not used as often as an MRI or a CT scan, but they may give your health professional additional information:

• Electromyogram and nerve conduction test, which can be used to diagnose certain nerve and muscle disorders, may be done in some cases for people who have signs of prolonged pressure on a nerve root.
• Myelogram, an X-ray study of the spinal canal that uses dye to more clearly outline the space containing the spinal cord. When myelography is used, it is almost always combined with a CT scan.
• Discography, which involves the injection of a dye into the jellylike center of a spinal disc to help diagnose disc problems
• Selective nerve root block, in which local anesthesia is injected beside a spinal nerve to confirm which nerve is causing the problem