Diagnosis

Electrodiagnostic Tests

Electrodiagnostic tests that analyze the electric waveforms of nerves and muscles may be useful for detecting nerve abnormalities that may be causing back pain and identifying possible injuries. They are also useful to determine if any abnormal structural findings on an MRI or other imaging test have real significance as a cause of the back pain. It should be noted that any nerve injuries that affect these tests may not be present for two to four weeks after symptoms begin.

Nerve conduction studies and electromyography are the electrodiagnostic tests most commonly performed.

Nerve Conduction Studies. To perform nerve conduction studies, surface electrodes are attached to the skin. Small electric shocks are then applied to measure the speed of nerve conduction.

Electromyography. To perform electromyography, a fine, sterile, wire electrode is inserted briefly into a muscle and the electrical activity is displayed on a viewing screen. Electromyography can be quite painful, and some experts question, in fact, whether it adds any valuable diagnostic information. They suggest it be limited to unusual cases or when other tests indicate that the condition is aggressive and may increase the risk for rapid, significant injury.

Other Tests

Blood and urine samples may be used to test for infections, arthritis, or other conditions.

Injecting a drug that blocks pain into the nerves in the back helps locate the level in the spine where problems occur.

A procedure called a facet block is also useful in locating areas of specific damage.

Provocative diskometry is a test that uses an injection of saline solution into the suspected disk to reproduce the pain, which is then followed by injection of an anesthetic to dull the pain.