A muscle twitch is a small, involuntary contraction caused by a muscle or group of muscles. This minor but uncontrollable twitching often is visible beneath the skin's surface and can look like a small ripple. Many times, muscle twitches — also called fasciculation — are brought on by stress and anxiety. This type of repetitive twitching typically occurs in areas such as the thumb, eyelid, and calf.
Also described as spasms, a variety of other factors can cause muscle twitches, including fatigue, exercise, dehydration, and diet deficiency. A muscle twitch can develop after ingesting too much caffeine. An adverse reaction to prescription drugs, including estrogen, corticosteroids, and diuretics, also can cause muscle spasms. When a muscle twitch occurs as a result of any of these factors, it is considered benign or harmless, and usually disappears within a few days. Benign muscle twitching is common and generally doesn’t require medical attention.
If a person suspects his spasms are caused by exercise, caffeine, or anxiety, there are several things he can try to reduce or eliminate them. He may want to stretch before and after a workout to relax the muscles. Eliminating drinks high in caffeine, like soda and coffee, may also help. To reduce stress, he may want to take a yoga or meditation class. Getting a good night's rest can also help most people.
A muscle twitch that lasts more than a few days could indicate a more serious condition, including a disease or nervous system disorder. Diseases that cause muscle spasms include amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease; muscular dystrophy; weak muscles or myopathy; and spinal muscular atrophy. A damaged nerve leading to a muscle also can produce a muscle twitch.
In addition to muscle twitches, symptoms indicating a nervous disorder are weakness; diminishing muscle size; and changes in — or loss of — sensation. In the case of long-term muscle twitches, a doctor may need to perform a physical exam to determine the cause. The doctor also may take a medical history to help make an accurate diagnosis.
There are several questions a doctor can ask to help narrow down the cause of persistent muscle twitches. She may ask about what muscles the twitches affect and if they usually happen in the same spot. The doctor may want to know how long the twitches last and how often they occur, as well as when the patient first noticed them. Along with the medical history, many medical professionals use diagnostic tests to determine the cause and severity of prolonged muscle fasciculation.