<s>[INST] My son has developed a tic which is causing his head to jerk to one side. He was in a wreck 4 yrs ago and the air bag went off in his face. About 2 years ago this tic started and is getting worse. Could the wreck have something to do with this or should we be looking for something else. [/INST] depends on how old he is.  tics are usually developmental brain problems that occur in young childhood and usually without trauma.  if it is truly from the accident or he is older it might be a different problem.  he should see a neurologist as there are good medicines for some movement disorders </s>