Hemi-facial spasm is a movement disorder which affects the muscles in one side of the face.
It usually starts around one eye and resembles blepharospasm in that it causes prolonged and severe blinking and closing of the eye lid. It then usually spreads to other muscles on the same side of the face causing the mouth to be pulled to one side.
This condition is not strictly a type of dystonia but is thought to be caused by either injury or irritation of a facial nerve.
Treatment is usually injections of botulinum toxin.
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