Explain the procedure of single-fiber electromyography (SFEMG).
Once the patient has been placed in the ideal position for performing single-fiber electromyography, the amplitudes of action potential are optimized by adjusting the electrode position whenever required. As the nerve starts firing action potential, rising phases and amplitudes of action potential is recorded. Action potential is measured from 20 pairs of muscle and on each muscle 3-4 incisions are made. Then the jitter value is displayed on the screen and mean value of consecutive differences of successive interpotential intervals (MCD) is calculated. The normal mean MCD value varies from 10–50 µs among different muscles.