In order to identify a neuromuscular disorder, neurologists utilize a range of diagnostic tools. In addition to a clinical evaluation and a family history, these may include:
Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that control them. These nerve cells, or motor neurons, transmit electrical signals that cause muscles to contract. An EMG translates these signals into graphs, sounds or numerical values that a specialist interprets. During a needle EMG, a needle electrode inserted directly into a muscle records the electrical activity in that muscle. EMG results can reveal nerve disorders, muscle dysfunction or problems with nerve-to-muscle signal transmission.
Evoked Potential Testing
|An Evoked Potential Test
An evoked potential test measures the time it takes for nerves to respond to stimulation as well as the size of the response. Depending on a patient’s symptoms and areas of complaint, nerves from different areas of the body may be tested. Types of evoked potential tests may include:
Visual evoked response or potential (VER or VEP), which is when the eyes are stimulated by looking at a test pattern. This type of evoked potential test is most commonly used to diagnose of multiple sclerosis (MS).
Auditory brain stem evoked response or potential (VER or VEP), which is when hearing is stimulated by listening to a test tone.
Somatosensory evoked response or potential (SSER or SSEP), which is when the nerves of the arms and legs are stimulated by an electrical pulse. Each type of response is recorded by measuring brain waves via electrodes taped to the head.
Evoked potential tests are non-invasive and painless, using sensory stimuli like strobe lights, auditory tones or electrical pulses to determine nerve function.
Serum Enzyme Tests
Serum enzyme tests can measure key enzyme levels associated with various neuromuscular diseases as well as increased muscle protein levels that build up as muscles are destroyed, making them an important aid in the diagnosis of neuromuscular diseases.
For some neuromuscular diseases, a final diagnosis depends on the analysis of a muscle biopsy. By removing a small amount of muscle tissue, your physician can test it for cellular protein abnormalities or characteristic changes in muscle composition. This is considered a minimally invasive surgical procedure which generally done under local anesthesia.
In addition to neuromuscular tests, your neurologist may order a CAT scan or MRI to get a more detailed look at your brain, spinal cord or musculature in order to detect deterioration or other abnormalities. CAT scans and MRIs use non-invasive, cutting-edge technology to take pictures of physical structures of the body from many angles.