Spasms occur when the part of the brain that controls movement malfunctions, causing involuntary muscle activity. A spasm may be a muscle contraction caused by abnormal nerve stimulation or by abnormal activity of the muscle itself.
Causes The cause of spasms is often unknown, but it can be due to an inherited genetic problem, a side effect of medications,
Parkinson's disease, a
stroke,
cerebral palsy or
multiple sclerosis. Spasms can occur in
dystonia, and in
spasticity.
Effects A spasm may lead to muscle strains or tears in
tendons and
ligaments if the force of the spasm exceeds the tensile strength of the underlying connective tissue. This can occur with a particularly strong spasm or with weakened connective tissue.
Types of spasm A
hypertonic muscle spasm is a condition of chronic, excessive
muscle tone (i.e., tension in a resting muscle). This is the amount of contraction that remains when a muscle is not working. A true
hypertonic spasm is caused by malfunctioning feedback nerves. This is much more serious and is permanent unless treated. In this case, the hypertonic muscle tone is excessive, and the muscles are unable to relax. A subtype of spasm is
colic. This is an episodic pain caused by spasm 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. ==See also==