No-one knows for sure about the actual cause. One thing is for certain though, that it is an unconscious act which is often made worse by anxiety or stress, and because it is an unconscious, involuntary act, the best way to deal with is with hypnotherapy.It accesses the healing power of your unconscious mind to simply switch the problem off.
I have had face tics all my life, but I have also suffered from depression and anxiety all my life and they have gotten bad throughout my life to the point that I am afraid to talk sometimes because it's embarrassing and my tics are so bad that sometimes I stutter. What do I do?
You can probably find the answers here at http://facialtichypnosis.com, a website devoted to treating facial tics with proven hypnosis techniques
Some tics are unconscious actions as Aicha said. Others are just a "misfiring" of the nervous system or motor cortex of the brain. Often you may get a muscle that is twitching in your eyelid or around the mouth, but it can happen anywhere on the body. I get one on occasion in my leg. It is annoying but they usually will go away all by themselves. Hiccups by the way are a form of tic, it is the diaphragm that is being affected though. If you have a facial tic that will not go away and is annoying or embarrassing, you might get relief by getting some botox injections in the area. Botox temporarily paralyzes the small muscles in the face, however you would need to do it a couple times a year to keep the muscles paralyzed.