A 45-year-old woman presented to the surgery outpatient department with complaints of difficulty in swallowing, predominantly solid food, for the past 6 months. She had lost about 7 kg weight in the last 3 months due to difficulty in food intake since the patient was mostly on liquid diet. She had no history of chronic heartburn, smoking, fever, or altered bowel habits. Routine blood investigations were within normal limits. She was advised barium swallow and subsequently was advised contrast-enhanced computed tomography (CECT) thorax. Barium swallow showed smooth external indentation on the esophagus, predominantly from right side and from posterior aspect with slight hold up of contrast [Figure 1]. There was no evidence of stricture or mucosal irregularity. CECT thorax confirmed the barium findings and the diagnosis [Figure 2].
What is the CT finding and final diagnosis?
What are the various types of this condition?
Axial CECT thorax showed right-sided aortic arch with four vessels originating from aortic arch. There was an aberrant left subclavian artery going posterior to the esophagus forming a vascular ring around esophagus causing extrinsic compression [Figure 2]. Based on the imaging findings, a diagnosis of right-sided aortic arch with an aberrant left subclavian artery was made. A clinical diagnosis of dysphagia lusoria was suggested on the basis of combined clinical and imaging findings.
Right-sided aortic arch is a common aortic arch anomaly and occurs in 0.05% of the population. It is commonly divided into three types based on the branching pattern: A right aortic arch with an aberrant left subclavian artery (Type 1), a right aortic arch with mirror image branching (Type 2), and a right aortic arch with isolation of the left subclavian artery (Type 3). Of this right aortic arch with an aberrant left subclavian artery as seen in our case is the most common type. This anomaly rarely produces symptoms and is usually detected incidentally. However, in some cases tracheal or esophageal compression due to the aberrant artery may be seen. Dysphagia lusoria is the term used to collectively describe all the aortic arch anomalies, which compress the esophagus and cause dysphagia.
In symptomatic cases, barium swallow studies will show a smooth impression in the posterior wall of the upper thoracic esophagus due to the aberrant vessel as is seen in the present case. However, in asymptomatic cases the barium swallow may be normal.
On CT or magnetic resonance scans, the diagnosis can be easily confirmed. The aortic arch is seen on the right side and the descending aorta may be seen either in midline or to the right. Four arteries are seen to arise from the aortic arch, first branch being the left carotid artery followed by the right carotid, right subclavian, and an aberrant left subclavian arteries in that order. The aberrant left subclavian artery passes posterior to the esophagus. In some cases, the aberrant left subclavian artery can arise from a diverticulum known as the kommerrel diverticulum. CT may demonstrate the "four artery sign," which shows two ventral carotid arteries and two dorsal subclavian arteries evenly spaced around the trachea.
Treatment depends on the severity of dysphagia. If the symptoms are mild as in our case, dietary modification is usually adequate. However in severe cases, surgery and ligation of the vessel may have to be performed.