Ruptured Internal Carotid Pseudoaneurysm in a Nasopharyngeal Carcinoma Patient with Skull Base Osteoradionecrosis

Abstract

Nasopharyngeal carcinoma (NPC) is a major head and neck cancer with a relatively high incidence of about 5.4 per 100,000 persons in Taiwan.1 The primary treatment of NPC has been external radiotherapy (RT). Now with combined chemotherapy and intracavity brachytherapy, more patients enjoy a longer survival.2 However, radiation-induced morbidity, including xerostomia, chronic otitis media, chronic paranasal sinusitis, temporal lobe necrosis, cranial neuropathy, carotid stenosis, palatal perforation, and brainstem damage, increases with more aggressive treatment.2, 3 The development of skull base osteoradionecrosis (ORN) has been reported.3 Rupture of irradiated great vessels is an uncommon complication, and it tends to occur in the carotid artery in patients with cancer of the head and neck.4 Sudden and massive hemorrhage is usually unexpected and fatal, particularly when it occurs in the nasopharynx, and it is one of the most dreaded post-RT complications among NPC patients. We describe the first published and successfully managed report of a case involving skull base ORN with a ruptured internal carotid pseudoaneurysm (PA) in NPC after irradiation. A 55-year-old man was admitted to our hospital on February 27, 2002, to undergo sequestrectomy for skull base ORN. He had had nasal fetid odor, headache, dry mouth, and bloodstained rhinorrhea for the past 1 month. The patient had hypertensive cardiovascular disease that had been medically managed for 20 years. He denied any history of trauma or surgery in the head and neck region. Four months before this admission, he had undergone treatment with concomitant radiochemo-therapy (CCRT) for NPC (T2b N2 M0, AJCC stage III, 1997). Radiotherapy was given to the nasopharynx with a 3-dimensional external-beam radiation dose of 73.8 Gy. Further boost was done using intracavitary brachytherapy for two 4.0-Gy fractions; 54 Gy had been delivered to the lower neck and 73.8 Gy to the upper neck. Concurrent chemotherapy with cisplatin and 5-fluorouracil was administered. One month before this admission, follow-up magnetic resonance imaging (MRI) showed no vascular anomaly or residual tumor. On admission, nasopharyngoscopy showed a crust with tenacious mucopus over the nasopharyngeal wall and exposed dark-gray necrotic bone on the whole roof of the nasopharynx. A central perforation of left eardrum coated with mucopus was noted on otologic examination. Fibrosis of oropharynx was also found. The preliminary laboratory results revealed normal platelet and coagulation profiles with the exception of normocytic anemia (hemoglobin 10.5 g/dL; normal range, 12.0 to 16.0 g/dL). Massive bleeding out of nostril and hemoptysis developed suddenly on the preoperative night. The bleeding comprised the upper airway and became life threatening. After resuscitation and a large amount of compressive oronasopharyngeal packing, vital signs were stabilized but active bleeding from the nose and mouth persisted. Conventional angiography of the left carotid system revealed a tapering tail distal to the carotid bulb. A PA, found distally at the tip of the tail before entering the skull base, was ruptured into the retropharyngeal space with contrast leakage (Fig 1). Embolization of the left internal carotid artery was uneventfully achieved with a balloon at the site of the left carotid bulb. Endoscopic sequestrectomy was performed and showed no recurrent cancer after pathologic examination. There was no episode of bleeding or neurologic defects in the follow-up period of 3 months. Radiotherapy is the mainstay treatment of NPC. The combination of external RT and brachytherapy has been reported to yield better local control and survival than external RT alone.2 However, the skull base and adjacent tissue inevitably receive a high dose of radiation during the course of this treatment. One study reported that all patients with NPC receiving boost brachytherapy had palate or sphenoid sinus perforation or nasopharyngeal necrosis.2 Thus, brachytherapy has been postulated as a predisposing factor for skull base ORN. Chang et al3 described 6 cases of skull base ORN after a combination of external RT and brachytherapy for NPC. Patients typically had an area of exposed and necrotic bone over the skull base and/or crust formation, and there was a higher incidence of involvement of adjacent structures such as the optic nerve, cavernous sinus, carotid artery, pons, and brainstem. If the condition is not treated, devastating complications such as internal carotid artery bleeding, blindness, and meningitis may occur. Catheter angiography of the left common carotid artery in lateral projection (A) and anteroposterior projection (B) shows gradual tapering of the left internal carotid artery beyond the carotid bulb and a bilobular pseudoaneurysm (arrows) from the left internal carotid artery at the high cervical segment. Although the exact mechanism of radiation-induced vascular damage is not clear, radiation is known to cause obliteration of the vasa vasorum, premature atherosclerosis, adventitial fibrosis, and weakening and necrosis of the arterial wall.4 Previous reports also noted that rupture of irradiated vessels tends to occur in larger arteries with high blood pressure (eg, the carotid artery in the head and neck). In this case, the progress of the internal carotid artery PA was relatively fast, occurring only 4 months after CCRT. It may be associated either with direct radiation-induced vascular injury or with skull base ORN sequelae and underlying hypertensive disease. Weakening of the wall of the postirradiated vessels could result in dissection or even rupture and may produce a PA that represents a disruption of the arterial wall with extravasation of blood that is contained by surrounding layers of connective tissue. To the best of our knowledge, severe hemorrhage from the nasopharynx as a complication of skull base ORN and a ruptured internal carotid PA in NPC has not been described previously. One previous report described internal carotid aneurysm rupture with bleeding into the ear canal secondary to ORN of the temporal bone.5 It seems that with the development of ORN in NPC, the risk of carotid artery disease tends to increase. Posttreatment NPC complications due to carotid artery disease may be difficult to recognize clinically, but a combination of clinical history, endo-scopic examination, and imaging findings contributes to the diagnosis. Although conventional MRI can define the location and extension of skull base ORN, it is less sensitive in the detection of vascular anomaly than in magnetic resonance or conventional angiography. The condition can easily masquerade as common bleeding, which is treated with posterior nasal packing or by tying off the external carotid artery. Therefore, before invasive surgical intervention, conventional angiography should be first considered for treating unpredicted bleeding. Once the entity is confirmed, concurrent embolization is justified. Our patient is alive only because he was hospitalized when the PA ruptured. Without immediate treatment in a hospital, the rupture would have been fatal.