Pseudoaneurysm of the Internal Carotid Artery after Retropharyngeal Abscess

Abstract

Infections of deep neck spaces and associated vascular complications have greatly reduced in frequency in the postantibiotic era. Involvement of the carotid artery is potentially lethal if not promptly recognized; however, the rare nature of this entity makes it less likely to be identified and treated. Historically, treatment has been open ligation of the involved artery with current literature supporting a possible role for the use of endovascular occlusion of the involved vessel.1, 2 We report a case of pseudoaneurysm of the internal carotid artery that was treated with a combined endovascular and open approach. A 10-month-old previously healthy infant developed fever and decreased appetite that progressed to right neck swelling despite timely administration of oral antibiotics. Evaluation revealed increased right neck swelling, greatly decreased oral intake, and a bulging posterior oropharynx. A neck computed tomography (CT) scan was obtained and showed a 4 × 4 cm hypodense area with an enhancing rim in the right retro- and parapharyngeal spaces. The carotid artery and internal jugular vein were displaced but patent. Operative drainage through a transoral incision was uneventful with cultures indicating methicillin-resistant Staphylococcus aureus (MRSA). After significant improvement on IV antibiotics, the patient was discharged with oral medications. The patient improved at home, but on postoperative day 9 he developed an acute increase in neck swelling, had an episode of profuse oral bleeding, and was returned to the emergency room. At this time, examination revealed an afebrile child with a large, tender, firm right-sided neck mass and bulging posterior pharynx. No discrete site of bleeding could be identified. The hematocrit had significantly decreased. A repeat CT (Fig 1) of the neck showed a 2 × 2 cm brightly enhancing mass within a surrounding hypodense rim with a neck extending toward the internal carotid artery. The neck was approximately 1 cm beyond the bifurcation of the common carotid artery, and the enhancing region extended above the angle of the mandible almost to the skull base. Pseudoaneurysm of the internal carotid artery inaccessible to immediate ligation was diagnosed. Consultation with vascular surgery and interventional radiology resulted in the decision to perform endovascular embolization of the internal carotid artery (Fig 2). The patient tolerated the procedure well. After allowing 24 hours for organization of the embolized thrombus, the child was returned to the operating room for a right neck exploration. A large hematoma was evacuated. The carotid artery was palpated, and no active bleeding or exposed embolization coils were identified. He was subsequently extubated on postoperative day number 3 and found to have no neurologic sequelae. He remained in the hospital on IV antibiotics for a total of 7 days and was discharged home on oral antibiotics. He has done well since that time. Axial CT shows brightly enhancing internal carotid artery pseudoaneurysm. Postembolization angiogram shows loss of internal carotid artery. Pseudoaneurysm of the internal carotid artery is an uncommon complication of infection in the head and neck. In the preantibiotic era, this was much more common, with a review of 227 cases presented in 1933.1 In the postantibiotic era, the incidence of vascular complications has decreased making recognition more challenging. The majority of patients are between the ages of 2 and 10 with the internal carotid artery most commonly involved. This is thought to be due to the close proximity of the internal carotid artery to the pharynx and its tortuous nature. Reported mortality associated with untreated pseudoaneurysm of the carotid artery can be up to 77% with treatment reducing this to 35%. This indicates the absolute need to recognize and control the bleeding. Symptoms of impending carotid rupture that have been previously identified include recurrent, undiagnosed oropharyngeal bleeding, slow or incomplete resolution of an appropriately treated neck infection, a rapidly expanding neck mass, anemia below clinically suspected levels, ecchymosis of the oropharyngeal mucosa, presence of a bruit over the mass, palsy of cranial nerves 9 or 12, and ipsilateral Horner's syndrome. The presence of bright red or projectile bleeding has been noted to be a particularly strong indication of arterial involvement. The initial bleeding episodes can be thought of as sentinel bleeds and, due to their self-limited nature, may not indicate the severity of the situation. Any patient with a history of deep space neck infection who presents with oropharyngeal or nasal bleeding warrants immediate contrast CT or angiography to rule out the presence of rupture of the cervical vasculature. Interventional neuroradiology can be useful to treat acute hemorrhage before transfer to the operating room or to treat surgically inaccessible areas at the skull base. The morbidity and mortality associated with ligation of the carotid artery is well known. In general, increasing age of the patient is associated with an increased risk of neurologic complication after ligation of the internal carotid. However, most of these infections occur in children, who have reduced morbidity with ligation of the cervical vasculature as extrapolated from the extra-corporeal membrane oxygenation (ECMO) experience. In conclusion, we present a case of pseudoaneurysm of the internal carotid artery 9 days after incision and drainage of a large retropharyngeal abscess. The patient had a single, profuse oral bleed, a decreased hematocrit, and neck and pharyngeal swelling acutely increased in size. The patient was successfully treated with a combination of endovascular occlusion and open evacuation of hematoma from the neck the following day. Successful patient outcomes depend on rapid recognition and treatment of this rare and potentially devastating complication of deep neck space infections.1, 3-5