"A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ such as the heart.
A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle cramp which is accompanied by a sudden burst of pain. A muscle cramp is usually harmless and ceases after a few minutes. It is typically caused by ion imbalance or muscle overload.
There are other causes of involuntary muscle contractions, and some of these may cause a health problem." - (en.wikipedia.org 26.11.2019)
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