Abstract
This study summarizes our experience of treating three rare cases of traumatic superior dislocation of the mandibular condyle into the cranial fossa and provides a potential treatment algorithm. Between the years 2002 and 2012, three patients with traumatic superior dislocation of the mandibular condyle into the cranial fossa were admitted to our department. After evaluating the interval from injury to treatment, the associated facial injuries including neurological complications, and the computed tomography imaging findings, an individualized treatment plan was developed for each patient. One patient underwent closed reduction under general anaesthesia. Two patients underwent open reduction with craniotomy and glenoid fossa reconstruction. All three patients were followed up for 1 year. Mouth opening and occlusal function recovered well, but all patients had mandibular deviation during mouth opening. Closed reduction under general anaesthesia, open surgical reduction with craniotomy, and mandibular condylotomy are the three main treatment methods for traumatic superior dislocation of the mandibular condyle into the cranial fossa. The treatment method should be selected on the basis of the interval from injury to treatment, associated facial injuries including neurological complications, and computed tomography imaging findings.
When the mandibular condyle collides with the top of the glenoid fossa of the temporomandibular joint (TMJ) under relatively strong external force, mandibular condylar neck fractures often occur due to the anatomical ‘safety mechanism’ for the skull base. For this reason, the incidence of mandibular condylar fracture is relatively high, representing 27–43% of mandibular fractures. However, under certain anatomical or physiological conditions, the mandibular condyle may penetrate the mandibular fossa superiorly into the cranial fossa, and result in dislocation of the mandibular condyle into the cranial fossa (DMCCF). Such a situation is extremely rare. DMCCF was first reported in 1963, and up until 2012, only 45 cases had been reported sporadically in the English language literature. The average age of these patients at the time of injury was 23.4 years and more than half were minors younger than 18 years of age. This injury is more common in female patients and the main cause is high-energy and high-speed traffic accidents.
Some special anatomical and physiological states may help explain the mechanism of this injury. Firstly, a small, round condyle may penetrate the glenoid fossa more easily than a normal, scroll-shaped condyle, which has been demonstrated experimentally by da Fonseca. Yale et al. reported that 2.8% of cadavers in their study had this kind of mandibular condyle. In addition, this morphology of the mandibular condyles is also found in 10-year-old children, which may explain why this type of injury occurs most often in young people. Secondly, a high degree of pneumatization of the temporal bone weakens the top of the glenoid fossa and thereby reduces the resistance of the bone to impact. Thirdly, the absence of posterior occlusion may lead to the consequence that any violent force is transferred directly to the TMJ along the ramus without being distributed to the maxilla via the teeth. Finally, if the patient opens the mouth at the time of impact to the chin, the violent force can be transferred directly to the condyle, which as mentioned above, lacks support from the teeth.
Mandibular asymmetry, limited mouth opening, and occlusal disorders are the main clinical features of DMCCF. These presentations are similar to the clinical manifestations of unilateral condylar fracture, which may lead to early-stage misdiagnosis and delayed treatment. Ohura et al. and Spanio et al. reported that misdiagnosis and delayed treatment occur in about half of these patients. Panoramic and plain radiographs cannot provide detailed information for diagnosis. Computed tomography (CT), especially coronal CT, is the main diagnostic imaging method. More than half of patients have no associated facial injuries, including neurological complications, but other injuries may include mandibular fracture, brain concussion, brain contusion, intracranial haemorrhage, epidural haematoma, cerebrospinal fluid leakage, hearing loss, ear canal injury, and facial nerve injury. Neurological complications and other associated facial injuries are important factors affecting the treatment strategy for DMCCF.
Three procedures have been reported for the treatment of DMCCF : (1) closed reduction under general anaesthesia, (2) open surgical reduction with craniotomy, and (3) condylotomy. An individualized treatment based on the patient’s status has been emphasized, and many scholars recommend similar treatment procedures.
Between the years 2002 and 2012, three patients with DMCCF were admitted to our hospital. These three patients had injuries with different features and received individualized treatment. The treatment of these three patients is summarized below. We also reviewed the previous literature on this subject and concluded that the time interval between injury and treatment, the associated facial injuries including neurological complications, and CT imaging findings are the main factors affecting the treatment strategy.
Materials and methods
During the years 2002 to 2012, three patients with rare DMCCF were admitted to the department of oral and maxillofacial surgery of our institution. All patients or their legal guardians agreed to inclusion in this study and provided signed informed consent. All three patients were females, aged 13 years, 25 years, and 22 years. One patient was injured in a fall and two were injured in motor vehicle accidents (MVA). These three patients were admitted to our hospital 1 day, 2 weeks, and 5 months after they had sustained their injuries. The first two patients had no neurological complications. The third patient had a serious contusion of the brain at the time of the injury and presented to our hospital after recovering from the contusion; this patient had also suffered a delayed fracture of the mandibular body.
Spiral CT was carried out for all three patients on admission. After evaluating the time interval between injury and treatment, the associated facial injuries, and the CT imaging findings such as the depth of penetration of the condyle into the cranial fossa, we developed different treatment plans for the patients. One patient underwent closed reduction under general anaesthesia and the other two patients underwent open surgical reduction and glenoid reconstruction ( Table 1 ).
| Case | Gender | Age, years | Cause of injury | Interval between injury and treatment | Neurological complications | Treatment |
|---|---|---|---|---|---|---|
| 1 | Female | 13 | Fall | 1 day | No | Closed reduction |
| 2 | Female | 25 | MVA | 2 weeks | No | Open reduction with craniotomy |
| 3 | Female | 22 | MVA | 5 months | Brain contusion | Open reduction with craniotomy |
Closed reduction
Case 1 was a 13-year-old female patient. The patient had accidentally fallen on her chin during exercise. After the injury she experienced limitations of mouth opening and malocclusion. The patient visited our hospital 6 h after the injury and no neurological complication was found. Physical examination showed deviation of the mandible towards the right side, 15 mm of mouth opening, an anterior open bite, and right-side premature contact of the posterior teeth. CT images showed a right-side glenoid fossa fracture and superior displacement of the right-side mandibular condyle into the skull ( Fig. 1 ). The patient was undergoing orthodontic treatment.
Intermaxillary elastic traction was applied for 4 days, but failed. CT showed incomplete intracranial displacement of the mandibular condyle without incarceration. After an evaluation of the situation, a timely treatment plan of closed reduction under anaesthesia was made. Under general anaesthesia, the right mandibular body was held manually and pushed downward; force was applied mainly on the right lower molars. After several attempts, the mandible reduction was achieved. The occlusion was recovered and then intermaxillary fixation was performed. Postoperative intermaxillary traction was applied for 1 month, and then mouth opening exercises were started. The patient was followed up closely.
Closed reduction
Case 1 was a 13-year-old female patient. The patient had accidentally fallen on her chin during exercise. After the injury she experienced limitations of mouth opening and malocclusion. The patient visited our hospital 6 h after the injury and no neurological complication was found. Physical examination showed deviation of the mandible towards the right side, 15 mm of mouth opening, an anterior open bite, and right-side premature contact of the posterior teeth. CT images showed a right-side glenoid fossa fracture and superior displacement of the right-side mandibular condyle into the skull ( Fig. 1 ). The patient was undergoing orthodontic treatment.
Intermaxillary elastic traction was applied for 4 days, but failed. CT showed incomplete intracranial displacement of the mandibular condyle without incarceration. After an evaluation of the situation, a timely treatment plan of closed reduction under anaesthesia was made. Under general anaesthesia, the right mandibular body was held manually and pushed downward; force was applied mainly on the right lower molars. After several attempts, the mandible reduction was achieved. The occlusion was recovered and then intermaxillary fixation was performed. Postoperative intermaxillary traction was applied for 1 month, and then mouth opening exercises were started. The patient was followed up closely.
Open surgical reduction and glenoid reconstruction
Case 2 was a 25-year-old female patient. The patient had sustained a scalp contusion and maxillofacial injury during a MVA. The patient had no malignant vomiting or neurological complications after the injury. The patient was admitted to our hospital 2 weeks after injury due to a limitation in mouth opening and malocclusion. Physical examination showed a right-side deviation of the mandible, 1 cm of anterior open bite, and immobility of the mandible. CT examination showed a skull base fracture in the right glenoid fossa, displacement of the right mandibular condyle into the skull, and incarceration at the fracture site ( Fig. 3 ). A treatment plan of open surgical reduction and simultaneous glenoid reconstruction was made.
