Clonus

Clonus is the name for involuntary rhythmic contractions of muscles or muscle groups. The term is from the Greek for "violent, confused motion". Cloni can happen as a sign of certain neurological conditions, such as epilepsy, stroke, and multiple sclerosis. They can also be a sign that the spinal cord was damaged. Cloni can also occur as a reaction to certain drugs.

Clonus Media

Clonus seen in a case of serotonin syndrome

This short article about medicine can be made longer. You can help Wikipedia by adding to it.