Bilateral mandibular coronoid hyperplasia causing trismus – a case report

Abstract

Mandibular coronoid process hyperplasia is a rare developmental condition. It commonly presents with progressive restriction of mouth opening, due to the impingement of the enlarged and elongated coronoid process on the distal aspect of the zygomatic arch during mandibular movement. It may present unilaterally or bilaterally. Surgical intervention to improve opening is advocated in cases with significant functional impairment, followed by post-operative physiotherapy. A case of bilateral coronoid process hyperplasia in a 28-year-old man treated with bilateral coronoidectomy, with subsequent post-operative relapse in degree of opening successfully treated via manipulation under intravenous sedation is presented. Clinical relevanceTo raise the awareness of clinicians to the possibility of coronoid process hyperplasia in cases of unexplained trismus.

Bilateral coronoid hyperplasia causing painless limitation of mandibular movement

“…This cartilage is covered by a thick fibrocellular capsule that is not evident before birth. Skeletal growth continues until adulthood along with transformation and proliferation of the fibrocellular layer's cells [3] .…”

“…Progressive and painless mouth opening reduction through several years, especially in men, is a common clinical sign of CPH. Progressive RMO is also observed in syndromes of pain and dysfunction of the TMJ (especially chronic disk displacement without reduction) and also uncorrected fracture of the jaw or the zygomatic bone, radiotherapy-induced fibrotic changes of the masticatory muscles, rheumatoid arthritis, primary and secondary neoplastic diseases (including osteoma and osteochondroma), progressive fibrotic change of the oral mucous membrane, ankylosing spondylitis, myositis ossificans, and tetanus [3] , [16] .…”

“…The purpose of surgery is to remove the coronoid process and eliminate the mechanical obstacle of mouth opening. Access area for the surgery may be intraoral or extraoral [3] . Removing a severely hypertrophic coronoid process is not possible intraorally.…”

“…Movements of a larger coronoid process interfere with the medial or temporal surface of the zygomatic bone. In addition, as this process grows gradually, the infratemporal space needed for rotation and translation of mandible is reduced, which results in reduction of the ranges of mouth opening and lateral excursion [2] , [3] .…”

Treatment of hyperplasia of the coronoid process of the mandible in adults: analysis of 42 literature reports and illustrative case

“…Trauma, ankylosis, masticatory contraction disorders, and dislocation of the articular disc without reduction should be included as differential diagnosis. However, in CPH, pain is not a frequent feature and imaging tests are essential in its definitive diagnosis [1,4].…”