Explain single-fiber electromyography (SFEMG).
Single fiber electromyography is a sensitive test that can give us information about the connection between the muscle, nerve and neuromuscular junction. Single fiber electromyography (SFEMG) was first established by Stalberg and Eskedt in the 1960s, and is of proven value in the diagnosis of neuromuscular disorders, especially myasthenia gravis. It allows the identification of action potential from individual muscle fiber and measures two features of the motor unit- fiber density and neuromuscular jitter. It is a very selective technique as it uses a small recording surface which is exposed at a port on one side of the electrode.