Diagnostic Tests: Bone Density, Nerve Function, Discography, Lab Tests


A Bone Scan may help to detect very fine stress fractures, arthritis, infections, or tumors. The patient is first injected with a liquid material that settles into the bone over a period of a few hours. During the test, the patient lies on the scanning table and a camera moves back and forth over the entire body. An area of increased activity will light up brighter (termed a hot spot or spot) than other parts possibly indicating a problem. This is a nonspecific test. When the results are positive (meaning abnormal) further investigation may be needed.

A Bone Density Scan is also called a Bone Mineral Density (BMD) test. This test measures the density or compactness of bone and is important in the diagnosis of osteoporosis (os-t-o-pour-o-sis). Further, a bone density scan may provide an early warning for the risk of developing osteoporosis. Computerized scanning equipment using a low dose of radiation measures bone density in the hip and spine. The test takes about 15 minutes.

Nerve Function Tests
Electromyography (elec-tro-my-ah-gra-fee, EMG), Nerve Conduction Velocity (NCV) and Discography (dis-ah-gra-fee) are tests used to confirm or deny nerve involvement. Sciatica (sy-attic-ka) is a symptom presenting as pain that radiates from the buttock down the leg. Nerve tests help to answer the question "is the pain coming from a leg muscle or is it a sign of nerve compression in the spine?"

Electromyography (EMG) may be used to determine if muscle function is normal or abnormal. An EMG tests for the nerve impulse coming from the brain and spinal cord. The nerve pulse is followed enroute to its final destination to determine if the nerve is blocked or delayed and where.

Nerve Conduction Velocity (NCV) is a sensitive test that is performed with an EMG. NCV stimulates a specific nerve and records the nerve's ability to transmit an impulse. This study may reveal where the nerve is unable to function normally.

Discography or a discogram is a type of x-ray used to view the intervertebral disc space. The abnormal disc is injected with an illuminating fluid under x-ray. The fluid injection may replicate the patient's symptoms, which may include leg pain. Abnormalities related to disc function or anatomical disorders might be determined by discography.

Laboratory Tests
A simple blood test may reveal infection, tumor or other spinal condition. Sometimes these disorders cannot be seen on an x-ray. A urinalysis (yu-ri-nal-is-sis) may reveal kidney stones or infection, which may cause severe back pain. Further, a urinalysis may detect by-products from muscle breakdown created by trauma or muscle disease.

In Summary
Osteoporosis (os-t-o-pour-o-sis) is an excellent example how diagnostic tests are used to help prevent and diagnose disease. When osteoporosis is found early, it can be easily treated.

This article is an excerpt from the book Save Your Aching Back and Neck: A Patient’s Guide, edited by Dr. Stewart Eidelson.

Updated on: 11/02/10
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Diagnostic Tests: X-Ray, CT Scan, MRI
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Diagnostic Tests: X-Ray, CT Scan, MRI

X-ray, CT Scan and MRI are types of tests used to help diagnose certain spinal disorders. Learn about these and other diagnostic tests.
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