Neonatal Coronoid Hyperplasia: A Report of a Case and Concepts to Promote Early Diagnosis and Treatment

Limited mouth opening in the neonatal patient is primarily caused by either soft tissue or hard tissue pathologic features. Differentiation between the two can usually be elicited by physical examination with the patient under anesthesia. Limited opening from soft tissue pathologic features can be increased with stretching. In contrast, osseous pathologic features will produce an anatomic stop. Syndromic cases with hard tissue pathologic features are primarily due to coronoid hyperplasia. Our aims are to help clinicians evaluate and identify mandibular hypomobility in the pediatric patient resulting from coronoid hyperplasia and to promote early treatment to improve long-term oral function. We present the case of a 2-month-old male who was born premature at 30 weeks by emergency cesarean section. Examination revealed multiple anomalies, including significant trismus with a maximal opening of 4 mm. A computed tomography scan revealed significant bilateral coronoid hyperplasia. At the age of 90 days, the patient underwent bilateral coronoidectomies with endoscopic guidance under general anesthesia. After resection, the patient was able to open his mouth to 25 mm. This opening was maintained with postoperative physiotherapy. Clinical problems can arise from the potential sequelae of neonatal trismus. Acutely, these problems can range from feeding difficulty and potential malnutrition to aspiration and emergent airway compromise. Long-term consequences include growth restrictions because of malnutrition, speech delay, muscle contracture and atrophy, facial asymmetry, and the risk of infection owing to poor oral hygiene. Information is limited about neonatal treatment of condylar hyperplasia in the published data. Treatment tends to be delayed owing to a late diagnosis and referral, and patients are prone to developing relapse. Postoperative physical therapy will help to prevent relapse and allows for maintenance of the improved jaw range of motion.