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Thyroid and Parathyroid Glands

Cernea CR, Dias FL, Fliss D, Lima RA, Myers EN, Wei WI (eds): Pearls and Pitfalls in Head and Neck Surgery. Basel, Karger, 2012, pp 20–21

DOI: 10.1159/000338062

1.10 Limited Parathyroidectomy

Keith S. Heller

New York University School of Medicine, New York, N.Y., USA

P E A R L S

• Preoperative imaging can localize a solitary adenoma in 90% of cases.

• Focused minimally invasive parathyroidectomy (PTX) can be performed under local/regional anesthesia as an outpatient.

• Position the patient with the head turned away from the side of the adenoma.

• Make the incision slightly off center, positioned higher or lower in the neck based on the location of the adenoma determined by imaging.

• Go through or lateral to the strap muscles, not through the midline.

P I T F A L L S

• Imaging frequently fails to detect multiple gland involvement.

• Reliance on imaging without measurement of intraoperative parathyroid hormone (IOPTH) may result in increased failure rate.

• Pneumothorax can occur in PTX performed under local anesthesia.

• The recurrent laryngeal nerve can be very close to adenomas located in the tracheal esophageal groove.

• IOPTH 'spike' due to manipulation of the adenoma can be misleading.

Introduction

Focused minimally invasive parathyroidectomy (PTX) can be performed because 80-85% of cases of primary hyperparathyroidism are due to a solitary adenoma. Imaging studies can predict the location of solitary adenomas in up to 90% of cases. Patients with multigland disease can only be identified by imaging in 50% of cases [1, 2]. For this reason, removal of all hyperfunctioning parathyroids (PTs) needs to be confirmed by IOPTH measurement. Focused PTX can be accomplished by several different surgical approaches including video-assisted surgery and even robotic surgery. I use conventional surgical techniques and instruments working through an incision about 3 cm in length.

Practical Tips

IOPTH Measurement. It is preferable to perform the assay in the operating room suite rather than in the central chemistry laboratory to minimize delay. Blood samples are obtained from a peripheral intravenous catheter when possible or from an intra-arterial catheter, but never directly from the jugular vein. A baseline sample is drawn when the patient is first brought into the operating room, before the neck is manipulated, to avoid an inappropriately elevated baseline parathyroid hormone (PTH) due to massaging the adenoma. Additional samples are drawn when the adenoma is removed and at 5-min intervals thereafter. Occasionally, there is a marked spike in the PTH level at the time the adenoma is removed. Failure to recognize this spike could result in the erroneous conclusion that additional hyperfunctioning PT tissue is present if the 5-min sample is the same as the baseline. The usual recommendation is that a decrease of PTH of more than 50% from the baseline value into the normal range assures cure of hyperparathyroidism in 98-99% of patients. The final IOPTH may be a more accurate predictor of outcome than the percent decrease. Patients with final IOPTH less than 40 pg/ml have a lower incidence of persistent hyperparathyroidism than those with higher values [3]. Resection of a single adenoma identified by preoperative imaging without measuring IOPTH results in persistent disease in 7% of patients [2].

Anesthesia. My preference is to use local/regional anesthesia. Contraindications include obesity, sleep apnea syndrome, and significant gastroesophageal reflux. The technique described by LoGerfo and Kim [4] is used. Intravenous sedation using propofol minimizes patient anxiety. Transient (several hours) vocal cord paralysis resulting from inadvertent vagus nerve block can occur. Pneumothorax can occur in up to 1% of patients after PTX under local/regional anesthesia due to negative intrathoracic pressure during spontaneous respiration.

Surgical Technique. The patient is positioned supine with the head extended and turned away from the side of the adenoma. A horizontal incision measuring 2-4 cm, slightly lateral to the midline, is planned. The location of the incision is based on preoperative imaging. Skin flaps are elevated. The fibers of the strap muscle are separated longitudinally. If the adenoma is in an inferior PT located inferior to the thyroid, the muscles are separated more medially. If the adenoma is in the retroesophageal location, the muscles are separated more laterally and dissection is performed just medial to the carotid sheath. The retroesophageal space can then be explored without having to mobilize the thyroid. To expose PTs behind the thyroid, the carotid sheath is retracted laterally and the thyroid medially. It is occasionally necessary to divide the middle thyroid vein. Although the recurrent laryngeal nerve may be near adenomas lying in the tracheal-esophageal groove, I do not routinely identify the nerve. Blunt dissection is employed and tissues are spread rather than divided. The adenoma is within a thin layer of fascia. Dissection under this layer will free the PT from its surrounding tissues and leave it hanging on its vascular pedicle, which then can be clipped. Even if the nerve crosses directly over the PT, it can be easily recognized and bluntly dissected away from the adenoma.

Postoperative Care. Patients are discharged after 3 h of observation on oral calcium supplements (1,000 mg/day). Serum calcium and PTH are measured 1 week postoperatively.

References

1 Johnson NA, Tublin ME, Ogilvie JB: Parathyroid imaging: technique and role in the preoperative evaluation of primary hyper-parathyroidism. AJR Am J Roentgenol 2007;188:1706–1715.

2 Bergson EJ, Sznyter LA, Dubner S, Palestro CJ, Heller KS: Sestamibi scans and intraoperative parathyroid hormone measurement in the treatment of primary hyperparathyroidism. Arch Otolaryngol Head Neck Surg 2004;130:87–91.

3 Heller KS, Blumberg SN: Relation of final intraoperative parathyroid hormone level and outcome following parathyroidectomy. Arch Otolaryngol Head Neck Surg 2009;135:1103–1107.

4 LoGerfo P, Kim LJ: Technique for regional anesthesia: thyroidectomy and parathyroidectomy. Oper Tech Gen Surg 1999;1:95–102.

Keith S. Heller, MD, FACS

Professor and Chief

Division of Endocrine Surgery

NYU Langone Medical Center

530 First Avenue, Suite HCC 6H

New York, NY 10016 (USA)

E-Mail keith.heller@nyumc.org