Medically reviewed by Brigid Dwyer, MD Key Takeaways Clonus causes involuntary, rhythmic muscle contractions when a muscle is stretched.It is often observed in conditions like multiple sclerosis, ...

Clonus, or the clonus reflex, is a neurological condition that results from damage to the nerve cells that control muscles. It can cause involuntary contractions, spasms, pulsing, tightness, and pain ...