HERNIATED LUMBAR DISKS: Diagnosis

When you first experience pain, consult your doctor. Your doctor will take a complete medical history to understand your symptoms, any prior injuries or conditions, and determine whether any lifestyle habits are causing the pain. Next a physical exam is performed to determine the source of the pain and test for any muscle weakness or numbness.

Your doctor may order one or more of the following imaging studies: X-ray, MRI scan, myelogram, CT scan, or EMG. Based on the results, you may be referred to a neurologist, orthopedist, or neurosurgeon for treatment.

> X-ray
This test uses X-rays to view the bony vertebrae in your spine and can tell your doctor if any of them are too close together or whether you have arthritic changes, bone spurs, or fractures. It's not possible to diagnose a herniated disc with this test alone.

MRI showing herniation at L3-4 		> MRI (Magnetic Resonance Imaging) scan
This is a noninvasive test that uses a magnetic field and radiofrequency waves to give a detailed view of the soft tissues of your spine. Unlike an X-ray, nerves and discs are clearly visible. It allows your doctor to view your spine 3-dimensionally in slices, as if it were sliced layer-by-layer like a loaf of bread with a picture taken of each slice. The pictures can be taken from the side or from the top as a cross-section. It may or may not be performed with a dye (contrast agent) injected into your bloodstream. An MRI can tell your doctor which disc is damaged and if there is any nerve compression. It can also detect bony overgrowth, spinal cord tumors, or abscesses.

> Myelogram
A myelogram is a specialized X-ray where dye is injected into the spinal canal through a spinal tap. An X-ray fluoroscope then records the images formed by the dye. Myelograms can show a nerve being pinched by a herniated disc, bony overgrowth, spinal cord tumors, and spinal abscesses.

Regular X-rays of the spine only give a clear picture of bones. The dye used in a myelogram shows up white on the X-ray, allowing the doctor to view the spinal cord and canal in detail. This test may be followed by a CT scan.

> Computed Tomography (CT) scan
A CT (computed tomography) is a safe, noninvasive test that uses an X-ray beam and a computer to make 2-dimensional images of your spine. Similar to an MRI, it allows your doctor to view your spine in slices, as if it were sliced layer-by-layer with a picture taken of each slice. It may or may not be performed with a dye (contrast agent) injected into your bloodstream. This test is especially useful for confirming which disc is damaged.

> Electromyography (EMG) & Nerve Conduction Velocity (NVC)
Electromyography (EMG) measures your muscle response to electrical stimulation. Small needles are placed in your muscles, and the results are recorded on a special machine. NCV is similar, but it measures how well your nerves pass an electrical signal from one end of the nerve to another. Because a herniated disc causes pressure on the nerve root, the nerve cannot supply feeling and movement to the muscle in a normal manner. These tests can detect nerve damage, both old and new.