The thyroid foramen: A case report and literature review of a largely unrecognized laryngeal anomaly

March 1, 2009
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Abstract

A thyroid foramen is a congenital linear opening located in the lamina of the posterosuperior portion of the thyroid cartilage. Although its overall incidence is reported to be as high as 39%, few practitioners are aware of its existence. We report the case of a 19-year-old man who was involved in a motor vehicle accident. He experienced transient left true vocal fold paresis and what were initially thought to be “bilateral thyroid cartilage fractures” based on computed tomography of the neck performed as part of his trauma evaluation. On further scrutiny, however, the “fractures” were determined to be bilateral thyroid foramina. The presence of the paresis in the setting of these thyroid foramina prompted us to review the literature to examine the significance of thyroid foramina and the vessels and nerves that course through them. The average diameter of a thyroid foramen is approximately 2.5 mm. These openings appear in an oblique orientation, and they occur both unilaterally and bilaterally. In 70% of cases, an anastomotic branch connects the external and internal branches of the superior laryngeal nerve. Embryologically, thyroid foramina are believed to arise from a combined branchial and neurovascular origin. A detailed understanding of laryngeal anatomy, including its variations and their physiologic implications, is important to head and neck surgeons.

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