A case of styloid process syndrome with complete bilateral ossification of the stylohyoid ligament

The present report describes a rare case of styloid process syndrome with complete bilateral ossification of the stylohyoid ligament. A 20-year-old man was referred to our department because of temporomandibular joint disorder. During the 3 years after his initial visit, several symptoms related to classic styloid process syndrome appeared on the right side while ossification of the right stylohyoid ligament was ongoing. Removal of the right ossified stylohyoid ligament was achieved via the external cervical approach, and the symptoms were resolved after the operation. However, 4 years after the first operation, several symptoms of carotid artery syndrome appeared on the opposite side, and ongoing ossification of the left stylohyoid ligament was evident. Removal of the ossified left stylohyoid ligament was achieved via the same approach as that for the first operation, and the symptoms were resolved completely. The present case suggests that a change in the stylohyoid ligament from a flexible chain to a stiff bone clasp is a decisive cause of styloid process syndrome.