What are muscle spasms?

A muscle spasm is a painful, involuntary movement or contraction of a muscle. A muscle spasm is also known as a muscle cramp. Muscle spasms and cramps are not the same as muscle twitching, which refers to very fine involuntary movements (fasciculations) of a small segment of muscle.

Skeletal muscles are muscles attached to bones that you control to move your body. Normally your skeletal muscles create movement by voluntary contraction. This occurs when muscles respond to a message sent from the brain through the nerves, which causes the muscles to contract, then relax. Normal voluntary muscle contraction involves a series of steps and requires normal amounts of oxygen, electrolytes (such as potassium and calcium), and glucose, all of which are supplied by your blood. Problems with the brain and nervous system, as well as the other required elements, may result in muscle spasms.

Skeletal muscle spasms are common and most people experience a temporary skeletal muscle spasm at some point in their life. The skeletal muscles that most commonly contract involuntarily include:

  • Back of thigh (hamstrings)
  • Calf muscle (gastrocnemius)
  • Front of thigh (quadriceps)

Leg cramps, sometimes called charley horses, are sudden and uncontrollable muscle contractions or spasms. They can occur with exercise or while sleeping and usually resolve just as quickly as they came. The pain from muscle cramps can be intense, but can often be relieved with gentle stretching and massage.

Skeletal muscle spasms and cramps are usually caused by overuse of the muscle, either from exercise or a repetitive motion. Spasms can also occur if a muscle is overstretched or held in the same position for too long. The muscle essentially becomes hyperexcitable and fails to relax. In some cases, the muscle may need to be massaged in order to release the contraction. Muscle cramps are often caused by or worsened when you are dehydrated and not getting enough fluids.

Muscle spasms and cramps can also be caused by neuromuscular disorders, such as multiple sclerosis or a spinal cord injury. Movement disorders called dystonias also lead to forceful contractions. Dystonias can also be a complication of stroke. Certain medications can cause involuntary muscle contractions as well.

Other types of muscle spasms

Although we often think of skeletal muscle spasms or cramps, other kinds of muscle, such as smooth muscle, can spasm or cramp. Smooth muscles are found in the walls of hollow organs in your body, such as your stomach, bladder, and blood vessels, and play an important role in normal organ function. For example, the muscles in your esophagus, the hollow tube that connects your throat to your stomach, are vital to swallowing, but they can suddenly contract and spasm and cause severe pain in the chest.

Cardiac muscle, which makes up the heart and is responsible for pumping blood throughout your body, is another type of involuntary muscle. An immediately life-threatening condition called ventricular fibrillation is rapid, disorganized and ineffective contractions of heart muscle.

Muscle spasms and cramps can be a sign of a serious disease, disorder or condition, such as multiple sclerosis, spinal cord injury, or stroke. In addition, angina and heart attack may be caused by spasms of the coronary arteries that supply blood to the heart. Seek prompt medical care if your muscle spasms and cramps last for a long time, recur, or are causing you concern.

Seek immediate medical care (call 911) if you, or someone you are with, have chest pain, difficulty breathing or swallowing, progressive muscle weakness, change in consciousness, inability to move a body part, or stiff neck.


What other symptoms might occur with muscle spasms?

Muscle spasms may occur with other symptoms, which vary depending on the underlying disease, disorder or condition. For example, severe skeletal muscle spasms may be accompanied by bruising and swelling of the area. Muscle spasms that are caused by a disorder affecting your whole body, such as hypothyroidism, may be associ... Read more about muscle spasmssymptoms


What causes muscle spasms?

Skeletal muscle spasms and cramps often occur when a muscle has been overused or overstretched. Muscle cramps can also be caused or worsened by dehydration and not getting enough fluids.

Muscle spasms and cramps can also be due to neuromuscular disorders and various diseases and conditions that affect the whole body, including Read more about muscle spasmscauses

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 6, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Bones, Joints and Muscles

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