Anatomical variants in the thyroid region and clinical implications for emergency airway procedures: A cadaveric case report

Abstract

Understanding the anatomy of the anterior neck is critical in invasive thyroid and airway procedures; however, there are a variety of possible deviations from textbook anatomy that may be present in this region. The thyroid ima artery is a variant supplying the thyroid gland that follows a medial course over the anterior trachea. Therefore, if not accounted for, it is a potential hemorrhage risk in emergency airway procedures and thyroid surgeries. Another anatomical variant in this region, a pyramidal lobe, is an extra thyroid lobe that typically extends superiorly from the isthmus and is attributable to incomplete involution of the thyroglossal duct during embryonic development. The pyramidal lobe can interfere with cricothyrotomy and can also make thyroid surgeries more difficult. For example, in complete thyroidectomies the presence of a pyramidal lobe could result in incomplete removal of the glandular tissue. To further document clinically relevant anatomical variation in this region, the present study examined 84 body donors for these two variations. Of these individuals, 14.3% had a thyroid ima artery, which is higher than previous estimates and suggests that this artery is at greater risk during thyrotomy than previously thought. Alternately, 20.2% of donors had a pyramidal lobe, which is a lower frequency than previous studies. Additionally, 6.0% of the sample exhibited both anatomical variants. Roughly three-quarters (71.4%) of the sample exhibited neither variant. This high occurrence of anatomical variation in the thyroid region suggests that caution is warranted during emergency airway procedures. The use of medical imaging prior to conducting a non-emergent procedure near the thyroid may reduce risks of iatrogenic damage.