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Neuroradiology Case of the Week

Case 355

October 2008

Jonathan R. Wood, BS and P-L Westesson, MD, PhD, DDS

Clinical Presentation: Patient is a 49-year-old male with a complaint of persistent nasal congestion and anosmia.

Imaging Findings: Axial contiguous tomographic sections without contrast were obtained through the orbit. A 2D reconstruction was performed because the patient was unable to tolerate maximum cervical extension which was necessary for coronal imaging.
     The right maxillary and bilateral ethmoid sinuses demonstrated diffuse opacification. The left maxillary sinus showed mucosal thickening and the osteomeatal complexes were blocked bilaterally. Also evident on the image was an abnormal position of the right TM joint. The right mandibular condyle was displaced medially and anteriorly

Diagnosis: Old fracture and malunion of right temporomandibular joint and diffuse maxillary sinus disease bilaterally

Discussion: The temporomandibular joint (TMJ) is formed by the articulation of the mandibular condyle, the mandibular fossa of the temporal bone, and the articular tubercle of the temporal bone. It is a modified hinge joint that allows movement in three planes: depression, elevation, protrusion, retrusion, and lateral movements. The surface of the joint is covered by fibrocartilage instead of hyaline cartilage as found in other synovial joints. At rest, the head of the mandibular condyle rests within the mandibular fossa, but to allow the mouth to open at a wide angle, the head of the condyle can slide from the mandibular fossa anteriorly to rest under the articular tubercle. Movements of the TMJ are produced mainly from the action of the muscles of mastication such as the suprahyoid, infrahyoid, temporalis, masseter, and medial and lateral pterygoid muscles.
     This patient’s malunion of the TMJ is likely from an old fracture that healed out of alignment. The condyle, due to the malunion, has dislocated anteriorly and medially. Dislocation of the TMJ or its disc is considered an internal derangement of the TMJ. Internal derangements can cause a variety of symptoms including difficulty closing the mouth, clicking sounds from the joint, restricted mouth opening capacity, deviation of the jaw upon opening the mouth, pain in the joint or muscles of mastication, crepitus, and headache.
     Trauma itself to the mandibular condyle can cause symptoms such as malocclusion of the jaw, pain, and neurologic problems if the auriculotemporal or facial nerves which run adjacent to the joint, are damaged. Fractures in the condylar neck are often associated with an open bite on the opposite site of the fracture and chin deviation towards the side of the face with the fracture.
     Treatment for a malunion, if the symptoms are severe enough to warrant it, is most commonly osteotomy and open reduction with internal fixation.

References:

1. Larheim TA, Westesson PL. Maxillofacial Imaging. 1st ed., Berlin: Springer-Verlag, 2006:143-156.
2. Moore KL, Agur, AMR. Essential Clinical Anatomy. 2nd ed., New York: Lippincott Williams & Wilkins, 2002: 552-554.
3. Katzberg RW, Westesson PL, Tallents RH, Drake CM. Anatomic disorders of the temporomandibular joint disc in asymptomatic subjects. J Oral Maxillofac Surg. 1996 Feb;54(2):147-53; discussion 153-5. [PubMed]
4. Kim DS, Kim MR, Choi JW. Malunion of the jaw fractures complicated following the primary managements. J Korean Assoc Oral Maxillofac Surg. 1999 Oct;25(4):357-361.
5. Prater ME, Bailey BJ. Mandibular fractures. Dr. Quinn’s Online Textbook of Otolaryngology. November 27, 1996.