A healthy 16-year-old female presented to our internal medicine clinic with a 6-month history of dizziness and two fainting attacks within the past month. She mentioned feeling a buzzing noise in the left side of her neck, for which she sought medical advice. Physical examination revealed left carotid bruit but was otherwise unremarkable. Lipid profile and hypercoagulable screen revealed normal values. Doppler ultrasound examination (Figure 1) and then MR angiography of the neck vessels (Figure 2) were performed.
How would you describe the findings? What are the diagnosis and associated risks?
Is there a differential diagnosis and what would you do next?
Doppler ultrasound of the carotid vessels showed normal vessel wall thickness with no atheromatous plaques, but there was a focal concentric narrowing of the lumen of the left common carotid artery (CCA). This was caused by a circumferential band of tissue (Figure 1a) projecting into the lumen and causing more than 70% stenosis; this was consistent with a congenital carotid web. The colour Doppler ultrasound demonstrated high-flow jet and aliasing in the area of highest velocity, with a significant increase in peak systolic velocity (to 410 cm s−1) and end-diastolic velocity (to 215 cm s−1) (Figure 1b). Time-of-flight (Figure 2a) and intravenous contrast-enhanced (Figure 2b) MR angiography of the neck vessels confirmed the ultrasound findings of a focal CCA web, located 4 cm below the bifurcation.
The patient was referred for vascular surgery, where an endarterectomy and a saphenous vein patch angioplasty were performed. To the naked eye, the intraoperative appearance of the artery suggested focal dissection (Figure 3). This was supported by the patient's sporting history of several years as a practitioner of karate, with possible exposure to focal trauma. However, the histopathological examination of the endarterectomy specimen revealed that the web was covered with intima and composed of benign fibromyxoid tissue with no evidence of dissection, haemorrhage, inflammation or atherosclerosis. The pathology findings are consistent with a congenital anomaly (web) rather than with a post-traumatic event. Follow-up after 6 months revealed a capacious patch angioplasty with no evidence of renewed stenosis.