Long-Term Pterygomandibular Ankylosis: Rare Presentation

Abstract

Pterygomandibular ankylosis describes a type of pseudo-ankylosis where any part of the coronoid process or TMJ structures is connected to sphenoid bone by a bone bridge. It is a rare presentation of extra-articular temporomandibular joint ankylosis. We present the surgical management of an impressive 17-year long pterygomandibular ankylosis in a 34-year-old lady with a satisfactory outcome.

Introduction

Pseudo-ankylosis of the temporomandibular joint (TMJ) is reported as an unusual condition that results in mandibular hypomobility due to a pathology extrinsic to the limits of this joint. It may be related to a fusion of the mandibular coronoid process to maxillary, zygomatic or temporal bone [1, 2], being extremely uncommon its fusion to the sphenoid bone. Factors such as radiotherapy, sequelae of zygomatic fractures, Jacobs’ disease, heterotopic bone formation between the coronoid process and zygomatic arch, sphenoid or posterior maxillary region have also been reported as causes of this condition [1, 3]. The authors discuss the clinical presentation and surgical management of a 17-year-long pterygomandibular ankylosis resulted from a firearm injury.

Case Presentation

A 34-year-old female patient, victim of domestic violence with a gunshot injury in her face about 17 years ago, sought our Department of Oral and Maxillofacial Surgery in October 2016. Patient’s main complaints were not being able to open her mouth and odontogenic pain due to inability to perform oral cleaning. At the time of injury (17 years ago), emergency care consisted of local surgical debridement. The patient reported had been under maxillo-mandibular blockage for 3 months, intermittently. Soon after this period and removal of the devices, she was not able to achieve satisfactory mouth opening (Fig. 1).

Fig. 1.

Clinical aspect of the patient preoperatively, with no mouth opening

At the initial clinical examination, right TMJ ankylosis was suspected due to a maximum mouth opening of 1 mm. However, panoramic x-ray and facial CT demonstrated the fusion between the right coronoid process along with the lateral pterygoid plate of the sphenoid bone, with a bone mass formation (Fig. 2). For better understanding and planning of the case, it was requested a facial prototype (CTI Renato Archer—Campinas/Brazil), which helped in the definition of the final surgical treatment plan (Fig. 3).

Fig. 2.

CT scan and panoramic exams depicting the site of the injury at the right zygomatic area with bullets fragments still present 17 years later

Fig. 3.

a–c Facial prototype with the planning osteotomies, d, e extra-oral C osteotomy and intraorally osteotomy for retrieving the extra-ankylotic bony mass, f aspect of coronoid process and bony mass removed

At the surgical room, nasotracheal intubation aided by bronchofiberscope was performed. A right 3-cm long retromandibular incision was made exposing the sigmoid notch so that a “C” osteotomy of mandibular rami encompassing the right coronoid process and cleavage of the bone segments could be achieved. Shortly thereafter, we could gain access by intraoral approach for removing the residual ankylotic block with a piezoelectric surgical device, avoiding iatrogenic damage to the noble structures in the pterygomaxillary region. Since there was no satisfactory buccal opening trans-operatively, it was decided to perform a contralateral coronoidectomy through intra-buccal access, thus obtaining 35-mm mouth opening after this maneuver (Fig. 3). No fixation devices were used, and at the same surgical time all the condemned dental elements were extracted.

In the immediate postoperative period, an aggressive physiotherapy program for active mouth opening was started. The patient received professional physiotherapy assistance for approximately 1 month, totaling 22 sessions, abandoning the treatment due to financial issues. Therefore, our surgical team instructed heron how to perform mandibular movements at home with regular tongue blades.

The patient in a follow-up of 36 months showed no evidence of facial motor deficits, residual paresthesia of the right-infraorbital nerve distribution, which she had already had in the preoperative period. Mouth opening of 38 mm without deviations was maintained still (Fig. 4), and she was referred for dental rehabilitation procedures, showing no interest in being submitted to a new surgical procedure to correct malar deformity.

Fig. 4.

Follow-up of the patient 3 years later with satisfactory mouth opening of 38 mm without pain

Discussion

Clinical cases of pseudo-ankylosis of TMJ with different origins have been described in the literature [1, 3, 4], with 88% of these cases associated with a history of traumatic events. Pterygomandibular ankylosis is a type of extremely rare extra-articular ankylosis [1, 5–7]. We hypothesized that in the path of the firearm projectile, there was formation of a hematoma, which was organized in a fibrous tissue and then a bone block formed due to the mandibular immobility caused by rigid maxillo-mandibular immobilization over a long period.

The treatment of pseudo-ankylosis of TMJ aims to restoring adequate mouth opening, masticatory function of patients [1]. Supper and Cotton [5] published an extremely unusual case of a 27-year-old male with fusion between the pterygoid lateral plate and the left mandibular ramus of unknown origin. The authors underwent open surgery and extra-orally removed the lateral aspect of the left mandibular ramus, where they identified a bone bridge, as well as an elongated left pterygoid plaque. After the procedure, the patient was able to maintain 30-mm mouth opening after 12 weeks of follow-up. In our case, the C-shape ramus osteotomy was suitable for removing with care the coronoid process along with part of the ankylotic bony mass.

In their paper, Mabongo et al. [7] described a surgical approach in a 5-year-old girl who presented bone fusion between the lateral pterygoid plaque at the medial aspect of the mandible, where intraoral access was carried out for resection in fragments of the ankylotic mass associated with bilateral coronoidectomy. In our opinion, bilateral coronoidectomy is essential in these cases, for a satisfactory mouth opening without additional mechanical impediments.

The immediate postoperative period is the most critical, for the patient needs to improve or maintain the mouth opening achieved during surgery and should be followed closely with an extensive physiotherapy program. Spijkervet et al. [1] emphasize the importance of patient awareness at each outpatient visit in relation to the satisfactory results obtained. For this, tongue blades stacked between the incisors were used in each session, adding two additional blades at each postoperative visit, which generated excruciating pain in the patient. The use of 24 spatulas corresponded to a mouth opening amplitude of 40 mm [1], and our patient reached a maximum total of 20 spatulas (35 mm).

Conclusion

In summary, pterygomandibular ankylosis describes a type of pseudo-ankylosis where any part of coronoid or TMJ structures is connected to pterygoid bone by a bone bridge, usually due to heterotopic bone formation. The treatment for this condition requires a detailed CT scan evaluation and prototypes. Postoperative physiotherapy is of outmost importance for surgical success.

Funding

No funding for this report was received by the authors

Compliance with Ethical Standards

Conflict of interest

The authors have no conflict of interest to report. We have read and understood the Helsinki Declaration, agree with its principles, and have no conflict with the declaration in investigations for compiling this article.

Informed Consent

Informed written consent was obtained from the patient. Additional consent was obtained from the patient for whom identifying information is included in this article.