Diagnosis of Carotid Fibromuscular Dysplasia Using Transoral Ultrasound in the Intensive Care Unit.

Fibromuscular dysplasia (FMD) is a rare, non-atherosclerotic vascular disease affecting medium to large arteries, especially the renal and internal carotid arteries (ICAs). The string-of-beads appearance, indicative of alternating areas of stenosis and dilatation, is a key imaging feature typically observed in the distal ICAs. Diagnosing FMD in critically ill patients poses challenges due to the risks associated with traditional imaging methods such as computed tomography angiography (CTA), magnetic resonance angiography, and digital subtraction angiography. We report a case of a 74-year-old woman diagnosed with stroke who required mechanical ventilation in the intensive care unit. Initial Doppler ultrasound revealed a fibrolipid plaque at the left internal carotid artery but could not assess the distal ICAs. Using a transoral approach with an endocavitary transducer, we visualized the distal ICAs, revealing the classic string-of-beads pattern and elevated peak systolic velocities indicative of stenosis. CTA confirmed these findings. The transoral ultrasound approach offers a non-invasive, bedside alternative for assessing the distal portions of the ICAs, making it particularly beneficial in critically ill patients. This case underscores the potential of this technique for timely diagnosis of FMD, warranting further research into its broader applicability in routine evaluations of suspected cases.