Muscles are controlled by electrical impulses from the body's nerves. When there is a problem with nerve function muscles can behave abnormally, such as twitching or paralysis. Pain and numbness are also possibilities and should be checked out. There are tests available to help determine the cause of such problems such as an EMG (electromyogram) which records the electrical activity of muscles. This test involves the insertion of a needle electrode into a muscle. There are also nerve conduction studies, which can find nerve damage to areas in the peripheral nervous system. In this case, several electrodes are placed so that when electrical pulses are given, the speed of response can be measured.
About the Tests
The EMG may seem intimidating, but it is quite safe—you won't feel more than a poke, and the needles are sterile. If you are undergoing either of these tests, it is important your doctor know if you are taking any medication or blood thinners, and if you have a pacemaker. Also avoid consuming anything containing caffeine for a few hours before the test.