Improving Outcomes After Thyroidectomy

Nancy A. Melville

August 16, 2011

August 16, 2011 — The use of a superior–inferior approach in identifying the recurrent laryngeal nerve (RLN) during a thyroidectomy appears to carry a lower risk hypoparathyroidism compared with an inferior–superior approach, according to a new study published online August 15 in the Archives of Otolaryngology–Head and Neck Surgery.

Thyroidectomy is common, particularly in regions where iodine deficiency rates are high, and the procedure can be tricky because of the close proximity of the thyroid to the RLN, write the authors, led by Bayram Veyseller, MD, from Bezmialem Vakif University in Istanbul, Turkey.

"[The RLN] runs in the tracheoesophageal groove to the larynx after exiting from the superior mediastinum, and its path has a very close anatomical relation to the thyroid gland, parathyroid glands, and inferior thyroid artery trunk," the authors explain.

The motor nerve supplies all of the intrinsic laryngeal muscles except the cricothyroid muscle, and in 1% to 2% of thyroidectomies, the RLN is unintentionally damaged, resulting in nerve paralysis.

Surgeons commonly take 1 of 2 approaches in identifying the RLN. One approach involves locating the nerve where it enters the larynx after superior pedicle ligation (superior–inferior), and the other locates the nerve in the trachea-esophageal groove, following it in the superior direction (inferior–superior direction).

In an effort to determine the level of risk involved with each approach, the researchers evaluated patients undergoing partial or total thyroidectomy between January 2006 and August 2009 at the Haseki Training and Research Hospital, Otorhinolaryngology–Head and Neck Surgery Clinic in Istanbul.

The participants included 67 patients in whom surgeons used the superior–inferior RLN identification technique, and 128 in whom the inferior–superior method was used. Patients' vocal cord function and blood calcium levels were evaluated the day after surgery, and the patients continued to be evaluated every 3 months until their calcium levels improved, for an average of 26 months.

Low blood calcium levels or unimproved RLN paralysis at 1-year postsurgery indicated the conditions were permanent.

Follow-up of the patients showed that 2 of the 128 patients, or 1.5% in the inferior–superior group, sustained permanent unilateral paralysis of the RLN compared with none in the superior–inferior group.

As many as 14 patients in the inferior–superior group experienced temporary hypoparathyroidism (16.2%), and 4 experienced permanent hypoparathyroidism (4.6%), compared with 4 (8.3%) experiencing temporary and none experiencing permanent hypoparathyroidism in the superior–inferior group.

"Comparing the 2 groups based on the frequencies of RLN paralysis and hypoparathyroidism, we found that complications were significantly lower in the (superior-inferior) group (P < .05) in terms of hypoparathyroidism," the authors write.

"The rate of hypoparathyroidism was significantly lower in the thyroidectomies that located the RLN using the superior-inferior approach. In our hands, the superior-inferior approach was a safer technique, in terms of avoiding complications," they conclude. "These results should be corroborated with larger case series."

The authors have disclosed no relevant financial relationships.

Arch Otolaryngol Head Neck Surg. Published online August 15, 2011. Abstract

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