Related conditions of hemifacial spasm include other neuromuscular disorders known as dystonias. They also cause involuntary contractions, but affect different areas of the body such as the legs and arms. One type of dystonia, benign essential blepharospasm, sometimes resembles hemifacial spasm but affects both sides of the face.
In addition, vision may be affected because spasms may force an eye to close. If contractions pull the mouth to one side, it could affect speech.