Spasm

In medicine a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes. Spasmodic muscle contraction may also be due to a large number of medical conditions, including the dystonias.

Hypertonic muscle spasms are caused by excessive muscle tone or residual tension in a resting muscle – the amount of contraction that remains when a muscle is not actively working. Hypertonia is beyond conscious control, it does not always produce direct awareness of its presence, and it surfaces in many ways not normally associated with muscle. What may appear as skeletal, circulatory, nerve, or inflammatory distress usually begins with hypertonic muscle spasm, a condition caused by the interruption of nerve feedback loops between muscle and brain.

True hypertonic spasm is caused by malfunctioning feedback nerves, is much more serious, and is permanent unless treated. Simply put, the hypertonic muscle is muscle tone run amok – the muscles are unable to relax.

By extension, a spasm is a temporary burst of energy, activity, emotion, stress, or anxiety.

A subtype of spasms is colic, an episodic pain due to spasms of smooth muscle in a particular organ (e.g. the bile duct). A characteristic of colic is the sensation of having to move about, and the pain may induce nausea or vomiting if severe. Series of spasms or permanent spasms are called a spasmism.

In very severe cases, the spasm can induce muscular contractions that are more forceful than the sufferer could generate under normal circumstances, which can cause tearing of tendons and ligaments.

Hysterical strength is argued to be a type of spasm induced by the brain under extreme circumstances.

Amongst causes of spasms are insufficient hydration, muscle overload, and absence of electrolytes.