Case report

A 32-year-old female presented with a history of an automobile crash 10 days earlier, she had cerebral contusion, facial ruptures and was unable to close her mouth. There had been bleeding from the left ear at the time of the accident. After conservative treatment, including dehydration therapy for cerebral contusion in the department of neurosurgery, the patient was referred to the authors because of malocclusion, limited mouth opening and premature contact of the left molars.

Clinical examination revealed that the mandible was retropositioned and was shifted to the left side. Anterior open bite and limitation of mouth opening were observed. Lateral mandibular motion was restricted bilaterally. The CT scan showed that the entire head of the left condyle was dislocated into the temporal fossa through the fractured glenoid cavity ( Fig. 1 ).

Preoperative CT scans showed superior dislocation of mandibular condyle into the middle cranial fossa. (A) Coronal image. (B) 3D reconstruction film.

Surgery was performed under general anaesthesia. Initially, a closed reduction was attempted as there was no condylar fracture, but this failed to reduce the condyle. An open reduction was attempted through a small submandibular incision. The left mandibular angle was approached and then held by Kocher forceps. Traction was applied in a downward direction. This also failed to reduce the condyle because almost the whole condylar head had dislocated into the fossa. To avoid further insult to the cranial base, a preauricular incision was made and the condyle was pulled successfully. There was no CSF leakage during this process. A temporal musculofascial flap and titanium network was used to repair the defect in the middle cranial fossa to prevent re-dislocation of the condyle ( Fig. 2 ). The articular disc was found to be displaced on the medial side and was restored between the condylar head and the temporal musculofascial flap. No neurological complications were observed postoperatively.

Postoperative CT scans showed reduction of the condyle and repair of the cranial fossa. (A) Coronal image (arrow showing the titanium network). (B) 3D reconstruction film.

Elastic inter-maxillary traction was performed and maintained for 2 weeks. Mouth opening was restored after surgery and occlusion remained stable during the 12-month follow up period.

Discussion

Displacement of the mandibular condyle into the middle cranial fossa is uncommon. The first case was reported by D ingman and G rabb in 1963 . Generally, impact to the mandible typically results in ipsilateral or contralateral condylar neck fractures . Thus, the applied energy is dissipated by the fractured condyle protecting the skull and brain from penetrating injury . In rare cases, the scroll-shaped mandibular condyle penetrates the middle cranial fossa though the central part of the glenoid fossa, which is the weakest part. High-speed road traffic accidents are the main cause of this type of injury , the proposed mechanism of injury being direct impact of the patient’s chin on the car dashboard. The possible etiology in the present case could also be direct impact on the chin during the accident.

Diagnosis of condylar displacement into the middle cranial fossa is achieved easily using clinical and radiographic examinations . Clinical signs include restriction of lateral mandibular motion and mouth opening, unilateral open bite with contralateral cross-bite. Radiographic examinations, especially CT scans are helpful for diagnosis and assessing treatment.

Various therapeutic methods including closed and open reduction, condylectomy and condylar reconstruction are used for the treatment of condylar dislocation into the middle cranial fossa . Closed reduction includes various types of traction. In case of no condylar fracture, closed reduction is the primary consideration as it is the simplest, safest and least traumatic procedure . If there is a condylar fracture or if the closed reduction is ineffective, open reduction should be considered. Although there was no condylar fracture in this patient, closed reduction by traction was unsuccessful. This may be correlated with cicatricial adhesion over time and the impaction of the whole condylar head deeply into the middle cranial fossa. In this patient, after the condyle was pulled out successfully, a large defect in the fossa was found, so a temporal musculofascial flap and titanium network was used to repair the damaged fossa. In this patient, the authors were able to relocate the articular disc and place it between the condylar head and the temporal musculofascial flap. If it is hard to pull out the condyle, condylectomy and simultaneous condylar reconstruction is recommended. Recently, C lauser et al. reported a case of superior dislocation of the left condyle with a fractured condyle. In this case, the condylar neck was resected and the condylar head was left in the medial cranial base. A new joint was created by remodeling the cut bony surface with a round bur. Postoperative inter-maxillary fixation is necessary to avoid malocclusion even if the reduction is successful. Elastic inter-maxillary traction was performed and maintained for 2 weeks in the present patient. The authors advocate the use of elastic traction because functional training can be performed simultaneously. It may also prevent the ankylosis of the temporomandibular joint postoperatively.