Irradiation-Induced High-Grade Carotid Artery Stenosis After Radiotherapy for Nasopharyngeal Carcinoma: Carotid Artery Stenting and Management of Recurrent In-Stent Re-Stenoses and De Novo Stenosis

The survival rate of patients with head and neck cancer has significantly increased over the past few decades because of improvements in radiation therapy and adjuvant therapy. Radiation therapy in the modern era delivers higher radiation doses with improved tumor control. However, in these patients, late complications including carotid artery stenosis may occur after irradiation. Previous findings suggest that patients with malignant head and neck tumors are at elevated risk of carotid artery stenosis and ischemic events after radiotherapy. The exact mechanism of carotid artery disease after irradiation is not fully known, but is associated with direct vascular damage and accelerated atherosclerosis. A 50-year-old man was diagnosed with nasopharyngeal non-keratinizing squamous cell carcinoma located on the left lateral wall of the nasopharynx, with tonsillar involvement and unilateral neck lymph node metastases (cT2N1M0), as confirmed by imaging and biopsy in September 2013. He had undergone tonsillectomy and left-sided neck dissection. Over the subsequent 6 weeks, he received radio-chemotherapy as an adjuvant treatment. In November 2014, we performed the first digital subtraction angiography because of a small hemorrhage resulting from a cerebral cavernoma; no vascular abnormalities were identified. Follow-up digital subtraction angiography was performed 3 years later because of an incidental finding of a small anterior communicating artery aneurysm; the results revealed a new asymptomatic high-grade stenosis of the distal left common carotid artery with irregular atherosclerotic changes and ulceration. Afterward, dual antiplatelet therapy was initiated with 1 × 75 mg clopidogrel per os (PO) daily and 1 × 100 mg acetylsalicylic acid PO daily. Antiplatelet therapy response assessments with VerifyNow and Multiplate revealed non-responsiveness to clopidogrel. A loading dose of 1 × 180 mg ticagrelor PO was administered on the day of the intervention, and an adequate antiplatelet response was confirmed. Carotid artery stenting was performed under general anesthesia in October 2017, without any peri- or postprocedural complications. The patient’s hospitalization course was otherwise uneventful. At 3 days after the treatment, he was discharged with a regimen of dual antiplatelet therapy with 1 × 100 mg acetylsalicylic acid PO daily and 2 × 90 mg ticagrelor PO daily. Follow-up examinations revealed in-stent restenoses and de novo stenoses of the left common and internal carotid artery 20, 42, 52, and 53 months after the first treatment. These were uneventfully managed through endovascular treatments with drug-coated balloons (DCBs) and additional stents. The purpose of this chapter is to provide an overview of radiation-induced carotid artery stenosis, emphasizing diagnosis, treatment options, and follow-up examinations. The findings demonstrate that carotid artery stenting can be performed safely in high-risk lesions and highlight the importance of meticulous follow-up after stenting. In-stent restenoses are frequent in radiogenic stenoses and require early diagnosis and re-treatment.