Laryngeal Electromyography
 |
Figure 1: Example of Laryngeal Electromyography procedure. We utilize a team approach. The voice specialist places the electrodes, while the neurologist runs the equipment and takes readings. Results are interpreted by both physicians. |
 |
Figure 2: Example of a tracing from a Laryngeal Electromyography study. The tracings are interpreted to give an idea of what is occurring within the muscle during certain maneuvers. |
Laryngeal electromyography (LEMG) is a test that gives information about the motor activity within the tiny muscles that control the vocal cords. This information is not available by any other test. This activity is important because it has implications for diagnosis and for predicting recovery of function. Diagnostically, LEMG is essential in determining the neuromuscular status of the vocal cords. Subtle weakness in the vocal cords may not be seen on endoscopic examination, and may only be evident after LEMG is performed. In cases of vocal cord motion impairment, LEMG can effectively distinguish vocal cord paralysis from impairment due to scarring. LEMG may also be useful in determining the need for further x-rays or scans to look for tumors.
The ability to predict recovery is an important function of LEMG. Following the onset of vocal cord paralysis, recovery has been noted to occur spontaneously up to 12 months following injury. Traditionally, patients with vocal cord paralysis have been treated with a "wait and see" policy. While this policy allowed some patients to avoid surgery, it also allowed some patients to continue to have symptoms (without treatment) for a full year, only to find out that in their paralysis was permanent. LEMG offers an alternative to the "wait and see" policy in that it often allows the physician to predict whether or not the paralysis is temporary or permanent early in the course of the problem. The physician can then make treatment decisions based on this information.
LEMG is performed routinely at the NYU Voice Center. The test is performed in conjunction with a neurologist specifically trained in interpreting electromyography. During a typical diagnostic LEMG test, the patient is laid down on an exam table with his/her head extended. Sticky pads are placed on the patient's face. The laryngologist sits at the patient's side, and inserts tiny needles into the various muscles being tested. The patient is asked to perform certain vocal tasks for each muscle tested. Typically, each patient examination takes less than 5 minutes. The patient may experience brief pain or discomfort during insertion of the needles, but most patients tolerate the test well. Following the test the patient may experience temporary bleeding or bruising at the needle insertion sites, a feeling of a "lump in the throat," and/or hoarseness for 1-2 days. It is important to inform the doctor if you are on any blood-thinning medications or if you have a bleeding disorder prior to having LEMG performed.
Patients having LEMG testing are encouraged to wear a shirt or top that allows access to the lower neck and to avoid neck jewelry on the date of the exam. A referral may be needed depending upon your health insurance coverage.
