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The state-of-the-art EMG Laboratory at HSC, staffed by Drs. Felice, Whitaker, and Andrews, performs nerve conduction studies, needle EMG, single-fiber electromyography (SFEMG), and other specialized procedures. Disorders from carpal tunnel syndrome to ALS are evaluated by experienced staff with patient comfort in mind. Physicians may refer patients directly for EMG testing by faxing the necessary information and reason for referral to 860.827.6286.
What is EMG?
Electromyography (EMG) is a clinical test for evaluating and recording the electrical activity of nerves and muscles. EMG testing is utilized by neurologists, neuromuscular medicine specialists, physiatrists, and orthopedic surgeons for evaluation of neuromuscular disorders including focal conditions like carpal tunnel syndrome, and generalized disorders like amyotrophic lateral sclerosis (Lou Gehrig disease), peripheral neuropathies, muscular dystrophies and myasthenia gravis.
A typical EMG test takes about 45-60 minutes and is composed of two parts - nerve conduction studies (NCS) and concentric needle electromyography (CNE). Nerve conduction studies test how well sensory and motor nerves conduct electrical signals. With surface electrodes attached to nerves and muscles, small electrical currents are used to stimulate individual nerves. Responses or action potentials are then measured. The size, shape and timing of these potentials provide information regarding the health of the nerves and muscles being tested. For example in carpal tunnel syndrome, a focal neuropathy, the median nerve is compressed in the wrist, and the timing of the action potentials is delayed. The compression and delay in these signals are the cause of carpal tunnel syndrome symptoms including nighttime hand numbness and pain. In generalized neuropathies like those associated with diabetes mellitus, NCS abnormalities are more diffuse.
Concentric needle electromyography usually follows NCS testing. For this test, small electrical wires or concentric needles are inserted into selected muscles for evaluation of electrical activity associated with both movement and rest of the muscle. Abnormal muscle signals during rest may indicate recent nerve injury or may show changes associated with certain types of muscle disorders (e.g., myotonic muscular dystrophy). Changes in muscle signals with activity are used to differentiate disorders affecting muscle from those affecting nerves. Occasionally, specialized EMG studies are needed to diagnose certain disorders. For example, a specialized procedure called single-fiber electromyography (SFEMG) is sometimes needed to diagnose a disorder called myasthenia gravis.
EMG studies should be performed by physicians experienced or trained in this testing. Some labs also employ an EMG technologist to assist the physician during the test. Prior to performing the test, the physician performs a physical examination. The clinical exam and the referral information guide the EMG physician on how to proceed with testing. Following the test, a report and interpretation are generated by the EMG physician and results are then faxed and mailed to the referring physician. Minor discomfort is sometimes noted during the needle examination; however, having an experienced staff usually helps to minimize needle-site discomfort.
The EMG Lab at Hospital for Special Care is staffed by two neuromuscular neurologists and an experienced EMG technologist, and utilizes all the latest and best equipment. Drs. Felice and Whitaker are board certified in neurology, clinical neurophysiology (EMG) and neuromuscular medicine, and both have extensive experience in EMG testing.
For further information about the EMG Lab or the Neuromuscular/ALS Center at Hospital for Special Care, please contact Sharon McDermott at 860.612.6305. Referral information for EMG testing or neuromuscular patient evaluation can be faxed to 860.612.6304 or e-mailed to email@example.com.