Anomalous course of the carotid arteries in the retropharyngeal space poses a surgical risk.

An anomalous course of the carotid arteries in the retropharyngeal space is an unusual finding that poses a risk of vascular injury during pharyngeal surgery. The risk is conferred by the close proximity of these arteries to the midline of the posterior portion of the pharynx. Two cases illustrate such a finding:

* Patient 1 was a 79-year-old man who had been diagnosed with left tonsillar squamous cell carcinoma. On endoscopic examination, we noted a significant distortion of the posterior pharyngeal wall, which warranted a biopsy. Computed tomography (CT) with contrast obtained prior to the biopsy demonstrated anomalous bilateral retropharyngeal internal carotid arteries and arteriosclerotic changes. These changes had caused retropharyngeal alterations, more pronounced on the left, adjacent to the tumor (figure 1).

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* In patient 2, a 26-year-old woman, we identified an anomalous course of the carotid arteries in the retropharyngeal area. The clinically silent anomaly was identified on CT as an incidental finding (figure 2).

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Embryologically, the carotid arteries originate in the third aortic arch and the dorsal aorta. Normally, the dorsal aortic root has descended into the chest by the eighth week of development, thereby straightening the course of the internal carotid artery. (1) However, it has been postulated that incomplete straightening of the carotid vessels enables the embryonic angulation to persist, resulting in congenitally tortuous or aberrant internal carotid arteries in the retropharyngeal space. Anatomic descriptions of tortuous internal carotid arteries in the otolaryngology literature range from mild kinking to the formation of complete circular loops. (1,2) Congenitally tortuous courses may become more pronounced in the elderly secondary to atherosclerosis and/or hypertension, as occurred in the first case noted here. (1) In such cases, widening of the pre-vertebral retropharyngeal soft tissues can also occur; this widening can be demonstrated on conventional imaging of the cervical spine. (2) However, CT, digital angiography (figure 3), and magnetic resonance angiography may clearly demonstrate the aberrant position and course of the carotid arteries to better advantage. (4,5)

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References

(1.) Shanley DJ. Bilateral aberrant cervical internal carotid arteries. Neuroradiology 1992;35:55-6.

(2.) Fix TJ, Daffner RH, Deeb ZL. Carotid transposition: Another cause of wide retropharyngeal soft tissues. AJR Am J Roentgenol 1996; 167:1305-7.

(3.) Walsh DW, Ho VB, Borke RC, Rovira MJ. Anomalous course of the common carotid arteries: CT and MRA illustration--A case report. Angiology 1998;49:235-8.

(4.) Collazo-Ornes P, Figueroa RE, Escobar W. Anatomia y patologia de la region infrahioidea. In: Rodriguez-Carbajal J, Palacios E, Figueroa RE, eds. Neurorradiologia: Cabeza y Cuello. Philadelphia: Lippincott Williams & Wilkins, 1999:555-71.

(5.) Shankar L, Mehta A L, Hawke M, Rutka J. High-resolution computed tomography of an aberrant internal carotid artery. J Otolaryngol 1992;21:373-5.

From the Department of Radiology (Dr. Palacios and Dr. Rojas) and the Department of Otolaryngology (Dr. Kirsh), Louisiana State University Health Sciences Center, New Orleans.