BMJ Case Reports | 2021
Common carotid artery trifurcation: a potentially dangerous anatomical variant
Abstract
© BMJ Publishing Group Limited 2021. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A 77yearold man with a squamous cell carcinoma of the right border of the tongue, clinical stage T2N0, underwent a partial glossectomy and a right supraomohyoid neck dissection. During neck dissection aberrant branching of the common carotid artery (CCA) was noted consisting on a carotid ‘trifurcation’ with the internal carotid artery (ICA) coursing posterolaterally, the external carotid coursing anteromedially and an additional anteriorly oriented arterial trunk (figure 1). After a short, ventral course this trunk gave an inferior and medially oriented branch heading towards the right superior lobe of the thyroid gland and turned anterior, superior and medially into the submandibular space to give off two branches. After the identification of these two branches as the lingual and the facial artery, respectively, the lingual artery was dissected and ligated to proceed with a right marginal glossectomy. After surgery, the patient underwent a CT angiogram to confirm and better understand the intraoperative findings (video 1 and figure 2). The study was performed on a 128row spiral CT scanner (Siemens Somaton Definition AS plus 128) and included a volumetric acquisition from the level of the aortic arch to the level of the orbital roof after the intravenous administration of 100 mL of nonionic iodinated contrast medium through an antecubital vein at a rate of 4 mL/s using an automated power injector (Mallinckrodt Optivantage). A bolus tracking technique was used to determine the individual start delay for the arterial phase, placing the region of interest immediately below the carotid bifurcation (CB). Image processing was performed at a dedicated workstation (Philips Intellispace) to obtain multiplanar and tridimensional reconstructions. This study showed a high CB on the right side (above the thyroid cartilage) compared with the left, confirmed the presence of three main branches coming off the common carotid due to abnormal branching of a thyrolinguofacial trunk from the anterior aspect of the CCA at the level of the CB and showed a hypoplastic external carotid artery (ECA) compared with the contralateral side. Several anatomical variants of the CCA and CB have been described: some are relatively common while others are quite rare. Being asymptomatic, they can go unnoticed during lifetime and are usually an incidental imaging or intraoperative finding. Radiologists and surgeons should be well aware of these variants as they can have major implications during surgical and/or interventional endovascular procedures. Knowledge of these variants is critical for treatment planning of atherosclerotic carotid artery disease, management of carotid body tumours and carotid body denervation procedures in case of carotid sinus syndrome. In the particular setting of head and neck cancer, they become clinically relevant during oncological surgery, reconstruction of surgical defects, embolisation of hypervascular/ haemorrhagic tumours and intraarterial chemotherapy. 2 6 Correct identification and ligation of the lingual artery is mandatory during a hemiglossectomy. Whereas this is usually straightforward, abnormal carotid artery branching may become confusing for an inexperienced head and neck surgeon with the risk of identifying and ligating the wrong vessel. Intraarterial chemotherapy/chemoembolisation has become a valuable treatment option for patients with locally advanced or recurrent head and neck cancers in which surgical resection would lead to an unacceptable functional and cosmetic result. In this