The EMG Clinic at UCSF Medical Center offers EMG (electromyography) testing which assesses the health of your muscles and the nerves controlling those muscles. You may have an EMG if you are experiencing symptoms of weakness and/or signs of impaired muscle strength. The test can help to differentiate primary muscle conditions from muscle weakness caused by neurologic disorders.
We also offer nerve conduction velocity (NCV) testing, which is often performed with an EMG. NCV tests the speed of signals through a nerve and is used to diagnose nerve damage or destruction. Occasionally, the test may be used to evaluate nerve or muscle diseases, including myopathy, Lambert-Eaton syndrome or myasthenia gravis.
In most cases, no special preparation is necessary. Avoid using any creams or lotions on the day of the test. Risks are rare, but you may experience some minimal bleeding or infection at the electrode sites.
For an EMG, a needle electrode is inserted through the skin into the muscle. The electrical activity detected by this electrode is displayed on an oscilloscope, and may be heard through a speaker.
After placement of the electrodes, you may be asked to contract the muscle (for example, by bending your arm). The presence, size, and shape of the wave form — the action potential — produced on the oscilloscope provide information about the ability of the muscle to respond when the nerves are stimulated.
You may feel some pain or discomfort when the electrodes are inserted, but most people are able to complete the test without significant difficulty. Afterward, the muscle may feel tender or bruised for a few days.
Before the test, you must maintain normal body temperature as low body temperature slows nerve conduction. Tell your doctor if you have a cardiac defibrillator or pacemaker, as precautions may need to be taken. There are essentially no risks associated with NCV.
Patches called surface electrodes, similar to those used for ECG are placed on the skin over the nerve at various locations. Each patch gives off a very mild electrical impulse, which stimulates the nerve.
The nerve's resulting electrical activity is recorded by the other electrodes. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to determine the speed of the nerve signals.
The impulse may feel like an electric shock. You will feel it to varying degrees, depending on how strong the stimulus is; it may be uncomfortable you. You should feel no pain once the test is finished.
You'll need a referral from your primary care provider or specialist to make an appointment. Once you have the referral, please call the number below.
400 Parnassus Ave., Eighth Floor
San Francisco, CA 94143
Phone: (415) 353-4965
Fax: (415) 353-2898
Hours: Monday to Friday, 8 a.m. – 5 p.m.
This clinic uses UCSF MyChart, an online patient service. Message your provider, request medication refills, view some test results and more.
Public parking for an hourly fee at UCSF Medical Center is available in the seven-level Millberry Union Garage at 500 Parnassus Ave. There are two garage entrances — one on the north side of Parnassus Avenue and another on Irving Street, just east of Third Avenue.
Another garage with an hourly fee, at 350 Parnassus Ave., is open Monday to Friday from 6 a.m. to 10 p.m.
Metered street parking is rarely available.
Patients being admitted to the hospital may be dropped off at the circular driveway leading to the main entrance at 505 Parnassus Ave. This area also may be used to pick up patients who are being discharged.
For more information about parking at Parnassus, call Campus Parking Services at 476-2566.
Valet parking service is available at the Ambulatory Care Center (ACC) at 400 Parnassus Ave. from 8 a.m. to 3 p.m. The valet service is free but patients must pay regular parking fees. For more information about the valet service, call (415) 476-6200.
A UCSF "greeter" also is available at the ACC from 8 a.m. to 5 p.m. to assist patients find their way.
UCSF Medical Center is accessible via Muni streetcar line N-Judah*, which stops at Second Avenue and Irving Street, and the following Muni bus lines, which stop in front of the hospital:
For more information about Muni visit, www.sfmuni.com.
* Wheelchair accessible bus routes