Abstract
In this paper, the case of trismus of a 10 year-old boy is reported and the pathogenic cause is considered. It was induced in a traumatic accident while playing football. The patient had complained of severe trismus and speech difficulties but no special organic changes were found in the oral region by clinical and radiological examinations. From investigations of family circumstances and articulation tests, it was judged that the abnormal conditions were caused by psychogenic conversion disorders. The most decisive factor was thought to be the excessive parental expectation towards him. In this case, brief psychotherapy and clinical exercise of breathing and reading based on operant method were effective.
