Carotid pseudoaneurysm is an unusual condition with high associated morbidity that brings with it significant challenges in diagnosis and management. It represents only 14% of all carotid aneurysms, an already rare condition (0.8-1% of all peripheral arterial aneurysms). (1) It develops secondary to a diverse range of aetiologies including trauma, iatrogenic injury, atherosclerosis, regional infection, vasculitis, radiation, and connective tissue disorders. Appropriate management must take account of aetiology location, and size. (2) Surgical repair of a carotid artery pseudoaneurysm is the first line of treatment but is technically challenging with significant associated risks including stroke, massive haemorrhage, and cranial nerve injury. (3) Furthermore, data on outcomes from various management approaches is sparse due to their rarity. This has resulted in a lack of evidence-based recommendations to guide clinical decision-making.

A 67-year-old man presented with a seven-week history of throat discomfort, left-sided facial headache, and neck swelling. His past medical history was significant for asplenia (post-trauma during childhood) and polymyalgia rheumatica. Imaging of his neck with ultrasound (US), computerized tomography (CT) and magnetic resonance imaging (MRI) confirmed a pseudoaneurysm at the left carotid bifurcation with associated inflammatory changes. This case represented a significant diagnostic challenge with both the identification of histological features of giant cell arteritis and response to antibiotic therapy suggesting possible concomitant infectious and vasculitic aetiologies.

Intravenous ceftriaxone and vancomycin were commenced empirically while investigations were ongoing. Following two weeks of conservative management, a repeat CT angiogram was conducted to assess for change in the size of the pseudoaneurysm size. While there was a reduction in the surrounding soft tissue swelling, the pseudoaneurysm had increased in size to 2.5 x 1.7cm. A decision was made to repair the left ICA pseudoaneurysm by excision with interposition vein grafting using the great saphenous vein (GSV). The GSV was harvested from the right groin. A standard approach to the carotid artery bifurcation was used. Proximal (common carotid artery CCA) and distal control (ICA and ECA) were obtained, and a shunt (Bard® BurbankTM, USA) was inserted from the CCA to ICA. The pseudoaneurysm was resected in its entirety, removing all of the abnormal carotid arterial walls. The GSV was used as an interposition graft between the CCA and ICA following ligation of the ECA. The resected segment of the artery was sent for histopathology and microbiological culture. Post-operative follow-up US duplex performed two weeks postoperatively confirmed a patent bypass with normal doppler waveform. Cultures of the carotid pseudoaneurysm were sterile. Histopathology reported an inflamed and thickened arterial wall with numerous foamy and multinucleated giant cells surrounding cholesterol clefts. A mixed inflammatory infiltrate was seen, including numerous lymphocytes and plasma cells, suggestive of giant cell arteritis (GCA). This diagnosis was confirmed following a clinical review by the rheumatology service. A temporal artery ultrasound showed no sonographic evidence of temporal arteritis. The patient was commenced on methotrexate and a tapering dose of corticosteroids. Before discharge from the hospital and on the advice of the ID team antibiotic therapy was changed to intravenous daptomycin for six weeks. This was recommended despite the absence of growth on the culture of the excised arterial wall.

This case highlights the complexities involved in the management of carotid artery pseudoaneurysms and the requirement for interdisciplinary input. It also emphasizes the need for further data on interventional outcomes to support clinicians in selecting optimal treatment strategies.

1. McCann RL. Basic data related to peripheral artery aneurysms. Annals of vascular surgery. 1990;4(4):411-4. 2. Welleweerd J, Den Ruijter H, Nelissen B, Bots M, Kappelle L, Rinkel G, et al. Management of extracranial carotid artery aneurysm. European Journal of Vascular and Endovascular Surgery. 2015;50(2):141-7. 3. Garg K, Rockman CB, Lee V, Maldonado TS, Jacobowitz GR, Adelman MA, et al. Presentation and management of carotid artery aneurysms and pseudoaneurysms. Journal of vascular surgery. 2012;55(6):1618-22.