Definition

• When muscle fibers contract involuntarily, this is a muscle spasm. It can be for a short twitch or a prolonged period of time until the fibers relax. Muscle spasms can occur as a result from cerebral or nerve issues firing signals to the muscles. They can also be caused by dehydration, muscle strains or trauma to the muscle itself.
  
  

Spasm vs. Cramp

• Muscle cramps are also involuntary contractions of a muscle. This contraction results in a hard, bulging muscle mass that is generally relieved within a few minutes. Cramps are generally connected to one motor neuron affecting one muscle and often occur from muscle overuse or sudden chilling. They can be overcome by stretching the area and are different than spasms, which affect more than one muscle and can be prolonged for hours.
  
  

Joint Locking

• One of the major symptoms of a spasm is the surrounding joint may lock. For instance, back and neck spasms are the most common types of spasms. If neck muscles have been strained by playing tennis and the person gets a chill, she may have a neck spasm. The result is a "crick" in the neck, preventing mobility. The person may not be able to turn his head in a certain direction for days or maybe even weeks. A back spasm may cause the back to lock up, rendering the person immobile until the spasm is relaxed.
  
  

Knots

• Normal stress can lead to an accumulation of fluids that create painful knots in muscles, which can be relieved with massage. A spasm will create a super-knot comprised of several muscles locked in contraction.
  
  

Other Spasm Symptoms

• Another type of spasm is angina where the chest muscles spasm as the heart tries to get more blood pumped into it. This type of muscle spasm suggests an underlying problem of atherosclerosis. Flu and colic often cause spasms in the stomach muscles leading to intense pain. An imbalance in electrolytes can lead to spasms thought to be associated with the flu and possibly colic in babies. Cerebral palsy and multiple sclerosis are two diseases that affect neural interaction and have a high spasm frequency in patients.