Pseudoaneurysms (PA), also termed false aneurysms, are a leakage of arterial blood, after a rupture of arterial endothelium, into the surrounding tissue with a persistent communication between the originating artery and the resultant adjacent cavity with the formation of a pulsating hematoma, which may lead to hemorrhage¹. It’s different from aneurysms, which are well-defined and abnormal dilations of blood vessels, that may be caused by trauma or flaccidity of the vessel walls, with preservation of all arterial layers².

Bilateral sagittal split osteotomy (BSSO) is the most frequently used osteotomy in orthognathic surgery to correct the mandibular position. It’s a procedure with a low incidence of complications that require urgent care. Pseudoaneurysm after a BSSO is a rare complication, with few reported cases, and is mostly related to the facial artery³.

The purpose of this study is to report a case of pseudoaneurysm of the inferior alveolar artery as a late complication of bilateral sagittal split osteotomy after a bad split.

Case Report

A 20-year-old male patient with no associated comorbidities was referred to the Oral and Maxillofacial Surgery Division of the Londrina University Hospital and diagnosed with a dentofacial pattern class III associated with a maxillary vertical excess. (Figure 1). Orthognathic surgery was recommended to improve facial harmony and the function of the stomatognathic system. Surgical planning involved a maxillary impaction and bimaxillary advancement, starting with the mandible. (Figure 02). Preoperative laboratory tests and cardiology assessment showed no alterations.

Figure 1: Preoperative open-bite occlusion of a patient with a dento-skeletal dentofacial pattern class III with vertical maxillary excess.

Figure 2: Virtual planning with ProPlan CMF (Materialise) software: bimaxillary orthognathic surgery with the correction of occlusal plane.

The surgical procedure was performed under general anesthesia with controlled hypotension. During the surgery, a Smith ramus separator and Smith sagittal split separators were used to complete the separation of the distal segment from the proximal segment. During the separation of the left side, a bad split occurred. Then, the correction of the osteotomy was achieved by performing the separation correctly at the base of the mandible with a reciprocating saw. After this complication was managed, surgery continued uneventfully, and no other problems were identified during the intraoperative.

The patient remained hospitalized for two days postoperatively with no complications and was discharged home after a computed tomography scan showed no alterations (Figure 3). At the two-week follow-up, he reported a slight swelling on the left mandibular body, with no associated pain and no progression. On clinical examination, a pulsating mass was observed at the posterior mandibular vestibule on the left side. (Figure 4). Due to the characteristics of the lesion during physical examination, the diagnostic hypothesis of vascular origin was raised, and an Angio tomography (angio-CT) was requested. A hyperdense lesion was observed in the region of the mandibular body on the left side (Figure 5). Therefore, the patient was referred to the vascular surgery team, whose diagnostic hypothesis after ultrasonography was a pseudoaneurysm of the left inferior alveolar artery. (Figure 6).

Figure 3: Post-operative 3D reconstruction: satisfactory position of the jaws. No alteration was observed.

Figure 4: Two weeks post-operative: slight increase in volume in the region of the left mandibular body associated with a pulsating nodule in the mandibular vestibule.

Figure 5: Post-operative CT angiography showing a hyperdense lesion adjacent to the left mandibular body, consistent with a vascular abnormality. Its superior position relative to the mandible, along with imaging evidence indicating the site of its neck (arrows), is suggestive of origin from the inferior alveolar artery.

Figure 6: Ultrasonography suggested a pseudoaneurysm on the alveolar inferior artery.

The vascular surgery team managed the pseudoaneurysm conservatively, using a compression technique guided by ultrasound.  After 2 weeks of follow-up, the pseudoaneurysm of the alveolar inferior artery had been thrombosed (Figure 7). The case has been followed up for 06 months so far, and the patient did not present new vascular alterations or clinical changes. (Figure 8).           

Figure 7: Ultrasonography showed the PA thrombosed after management with compression.

Figure 8: 06 months postoperative with final occlusion as planned. Patient without swelling or pulsatile nodule.