Hemifacial spasm (HFS) is a rare movement disorder that causes involuntary muscle contractions on one side of the face. It typically starts with painless but annoying twitching around one eye. Over ...

You're relaxing on the sofa when suddenly your eyelid starts twitching. Or perhaps it's a muscle in your arm, your leg, or ...

Infectious agents can cause muscle twitching and spasms, too. The most commonly known is probably tetanus, which causes a phenomenon called lockjaw, where the neck and jaw muscles contract to the ...