ABSTRACT
BACKGROUND: It is well known that the inferior parathyroids are more difficult to preserved than the superior parathyroid glands because the inferior parathyroid glands have more anatomical variations. METHODS: The authors analysed the gross surgical findings of a total of 411 inferior parathyroid glands in 314 total thyroidectomy cases. The inferior parathyroid glands were grouped according to patterns based on their location and arterial blood supply. RESULTS: Type 1 (location: posterior surface of the lower thyroid pole; artery: inferior branch of the inferior thyroid artery): incidence 51% and presevation rate 62%. Type 2 (location: thyrothymic ligament or in the thymus; artery: inferior branch of the inferior thyroid artery): incidence 27% and preservation rate 86%. Type 3 (location: apart from the lower thyroid pole; artery: inferior branch of the inferior thyroid artery): incidence 6.1% and preservation rate 92%. Type 4 (location: anteriorly on the lower thyroid pole; artery: inferior branch of the inferior thyroid artery): incidence 4.1% and preservation rate 33%. Type 5 (location: lower thyroid pole; artery: comes out from the thyroid gland): incidence 4.1% and preservation rate 0%. Type 6 (location: lower thyroid pole; artery: branch of the superior thyroid artery): incidence 3.6% and preservation rate 80%. Type 7 (location: lower thyroid pole; artery: embedded in the thyroid gland): incidence 2.9% and preservation rate 36%. Type 8 (location: more superior than usual; artery: superior branch of the inferior thyroid artery): incidence 0.7% and preservation rate 67%. Type 9 (location: lower thyroid pole; artery: thyroid ima artery): incidence 0.5% and preservation rate 100%. CONCLUSIONS: The most identified inferior parathyroids belonged to the usual types, and their pre-servation rate were relatively high. However there were some unusual types though their incidence was low. Thus, accurate anatomical knowledge of variations in the location and the blood supply of the inferior parathyroids is needed to enhance the preservation rate.
