Arteriovenous Fistula with Pseudoaneurysm and Facial Palsy Following Bilateral Sagittal Split Osteotomy: A Case Report

Abstract

Bilateral sagittal split osteotomy is a commonly used, standard procedure in orthognathic surgery to correct malocclusion and jaw misalignment. Postoperative vascular complications are extremely rare and under-reported in the literature. This contribution presents the case of a 48-year-old male patient who underwent bilateral sagittal split osteotomy due to class II skeletal malocclusion. There were no abnormalities during the surgery. However, the patient developed facial palsy and experienced a pulse-synchronised murmur. Computed tomographic angiography (CTA) revealed an arteriovenous fistula between the right external carotid artery and the pterygoid plexus with pseudoaneurysm. Following the diagnosis, the patient was successfully treated with an intervention involving coiling and sealing with histoacrylic glue. It is crucial to be aware of serious vascular complications following orthognathic surgery, as a delay in diagnosis and treatment can lead to life-threatening bleeding or long-term damage. CTA is the most rapid and accurate method of confirming the diagnosis. If there is clinical suspicion, this examination should not be delayed, and the therapeutic approach should be determined on an interdisciplinary basis.

1. Introduction

Bilateral sagittal split osteotomy (BSSO) is a commonly used orthognathic procedure to correct malocclusions in syndromic and non-syndromic skeletal irregularities and mandibular misalignments. Common complications following BSSO are diverse and may include nerve lesions, failure of osteosynthesis material, pseudarthrosis, temporomandibular joint complaints, and non-union of the bone segments [1]. However, postoperative vascular complications are an absolute rarity. According to the latest systematic review by Kumar et al., there are only eight cases of pseudoaneurysms after BSSO in the English-language literature [2]. To the best of our knowledge, there is no case report of arteriovenous fistula or even a combination of these two vascular complications after BSSO to date.

Pseudoaneurysms can result from damage to the vessel wall due to iatrogenic or traumatic causes (blunt force). If these structures rupture, life-threatening mass bleeding can occur, which is often difficult to control [3]. This article reports on a successfully treated case of a postoperative arteriovenous fistula between the external carotid artery and the pterygoid plexus with pseudoaneurysm after BSSO. This is intended to help raise reader awareness and provide recommendations for complication management.

2. Case Report

A 48-year-old male patient was referred from orthodontics to the Department of Oral and Maxillofacial Surgery for mandibular advancement surgery after appropriate shaping of the dental arches with orthodontic braces. The indication for BSSO was a skeletal class II malocclusion. There were no abnormalities in the patient’s medical history. An experienced senior consultant performed the surgical intervention under general anaesthesia. The surgical procedure was the BSSO modification according to Hunsuck and Epker. All technical features have already been sufficiently described in the literature [4,5,6]. No excessive intraoperative bleeding or other complications (e.g., bad split) occurred. Routine post-operative x-rays confirmed the appropriate positioning of the mandible and the placement of the osteosynthesis material, consistent with the preoperative model surgery. The surgical splint was retained intraorally, as per standard protocol, and postoperative occlusion was satisfactory. Figure 1 illustrates the accurate postoperative advancement of the mandible (Figure 1).

However, on the first postoperative day, the patient presented with mild peripheral facial palsy on his right side. Therapy with vitamin B complex and corticosteroids was initiated, and the patient was discharged on the third postoperative day. During the second routine follow-up check on the fourteenth postoperative day, the patient reported hearing a murmur synchronised with his pulse in the right ear. The patient reported hearing this murmur a few days before the follow-up, and it had worsened over time. Clinical examination showed a palpable pulsatile mass in the area behind the right jaw angle.

Following the clinical suspicion of vascular involvement, emergency computed tomographic angiography (CTA) of the head and neck region was performed. CTA revealed a circumscribed pseudoaneurysm in the area of the right jaw angle, with a maximum diameter of 1.7 cm, originating from a branch of the right external carotid artery. There was no evidence of active extravasation (Figure 2).

The treatment options were discussed in an interdisciplinary meeting. Open surgical revision and ligation of the right external carotid artery would have been associated with a high risk for the patient due to the difficult location of the vascular malformation. As access to the pseudoaneurysm would also have required another mandibular split and the risk of rupture with potentially life-threatening mass bleeding was very high, a less invasive endovascular radiological approach was chosen. Under general anaesthesia, the Seldinger catheter sheath technique was applied. An extensive arteriovenous fistula in the area of the right jaw angle with associated pseudoaneurysm was identified. The fistula originated from the external carotid artery at the offshoot of the maxillary artery with connection to the pterygoid venous plexus. Due to the significant shunt volume, a balloon catheter was placed over the outlet of the fistula and inflated to reduce the flow rate, allowing histoacryl adhesive glue to be applied in the right position for complete closure. The pterygoid plexus was preserved. Using the balloon catheter, several platinum coils were then implanted into the pseudoaneurysm. Due to the suspected unstable position of the coils, the entrance to the pseudoaneurysm was additionally sealed with histoacrylic glue. Control angiography demonstrated complete closure of both the fistula and the pseudoaneurysm (Figure 3).

Postoperative recovery was unremarkable. Unfortunately, the mild facial palsy remained still subtly visible twelve months postoperatively, despite active physiotherapy and electrotherapy. The team assumed that gradual development of the pseudoaneurysm postoperatively compressed the facial nerve, causing the palsy. At follow-up appointments 12 months post-intervention, the patient reported no symptoms related to the vascular complications. This case follows the CARE case report guidelines (Supplementary File S1).

3. Discussion

The most common long-term complications of BSSO are a persistent neurosensory deficit of the inferior alveolar nerve, relapse after advancement of the jaw, temporomandibular joint dysfunction, and resorption of the condyles [7,8,9]. This article is intended to raise awareness of the possibility of vascular complications. Even though they are very rare, it is crucial to be conscious of them, especially in this highly elective surgery, in order to enable the surgeon to react immediately and appropriately in such scenarios. The danger lies in the occurrence of potentially life-threatening mass bleeding. A certain amount of overt and hidden blood loss is always expected intraoperatively, and a blood transfusion may be necessary postoperatively [10,11]. The literature provides only weak evidence of serious complications like excessive bleeding from fistula formation and pseudoaneurysms, likely due to underreporting. According to a systematic review (a total of 33 patients were included) from Kumar et. al., most pseudoaneurysms are observed after LeFort I osteotomy (69.7%), and only 24.2% in patients after BSSO [2]. A certain temporal variance must be pointed out in the manifestation of symptoms in vascular complications. Avelar et al. describe that pseudoaneurysms usually occur 3 days to 8 months after osteotomy [12]. Within this long postoperative period, acute haemorrhage, new oedema, or haempulsation can occur. Accordingly, the patient described above presented on the fourteenth postoperative day, i.e., after a relatively short period of time. As in our case, other patients reported in the literature with pseudoaneurysms after jaw osteotomy have also had pulsatile murmurs, which could be localised and were generally heard noisily during systole [13,14]. In addition, the occurrence of bleeding (e.g., epistaxis) has also been mentioned among the clinical symptoms, although haemorrhage episodes have only been reported inconsistently [2]. Pseudoaneurysms can be the result of other intraoperative complications. In their case report, AbuKaraky et al. found that this vascular complication was due to a bad split. The authors suspected that the inferior alveolar artery was injured while the split was being completed with an osteotome positioned too posteriorly towards the condyle [15]. In the case presented here, unfortunately, no specific cause could be identified in the retrospective analysis. The treatment of pseudoaneurysms depends primarily on their localization. If the location is superficial and easily approachable, open surgical revision with ligation is a treatment option. However, it must be borne in mind that there is an extensive network of collateral arterial anastomoses in the head and neck region. According to Rosenberg et al., unilateral ligation of the external carotid artery below the lingual and facial arteries only leads to a partial (40%) reduction in blood flow in the maxillary artery [16,17]. In demanding locations, at depth, an endovascular procedure is better suited to avoid extensive surgical dissection and/or reconstruction, which are associated with high morbidity and mortality [18]. In accordance with the existing literature, endovascular intervention is a safe method with a very low rate of postoperative complications as well as neurological and embolic events and should, therefore, be considered the method of choice [2,19,20].

4. Conclusions

It is crucial to be aware of serious vascular complications following orthognathic surgery, as a delay in diagnosis and treatment can lead to life-threatening bleeding or long-term damage. CT angiography is the most rapid and accurate method of confirming the diagnosis. If there is clinical suspicion, this examination should not be delayed, and the therapeutic approach should be determined on an interdisciplinary basis.