Minimally Invasive Radioguided Parathyroidectomy

Minimally Invasive Radioguided Parathyroidectomy

Author: Joshua Hagood

Performing surgeon/coauthor: Brendan C. Stack, Jr., M.D., FACS, FACE

Department of Otolaryngology – Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA

Primary hyperparathyroidism is a disease caused by overproduction of parathyroid hormone (PTH). This condition is most commonly caused by a solitary, hyperfunctioning, adenoma among one of the four parathyroid glands. The hallmark finding of hyperparathyroidism is hypercalcemia which can manifest symptomatically as nephrolithiasis, diabetes insipidus, renal insufficiency, bone pathology, gastrointestinal symptoms, and neuropsychiatric disturbances (remembered as “Stones, Bones, Groans, and Psychiatric overtones”). Minimally invasive Radio guided Parathyroidectomy (MIRP) is a curative procedure for primary hyperparathyroidism that can use both radionuclide guidance and intraoperative PTH measurements to confirm the removal of the offending adenoma. Radionuclide guidance is performed via the injection of 99mTc-sestamibi, which is a radiomarker that sequesters within adenomatous/hypermetabolic parathyroid tissue. Intraoperatively, the amount of 99mTc-sestamibi within excised tissue can be measured with the use of a handheld gamma probe.

-Endotracheal Nerve Integrity Monitoring System (NIMS)
-Gamma Probe
-Intraoperative PTH assay equipment

-The surgical bed is rotated so that the patients head is pointed away from the anesthesia team, and elevated 30 degrees upward. A shoulder roll is placed underneath the patients shoulders in order to extend the neck. The patient is intubated with an endotracheal NIMS under direct vision by a glide scope -A 3cm midline incision is made halfway between the inferior border of the cricoid cartilage and the sternal notch -a sample of subcutaneous fat is removed and saved to be used as a negative control for the gamma probe -dissection is continued down to the strap muscles, and an Alexis self-retaining retractor is placed to maintain exposure -Strap muscles are divided vertically in the midline and retracted laterally -blunt dissection is used to retract the thyroid medially -The parathyroid is identified and resected carefully with either blunt spreading or electrocautery to preserve the thyroid capsule and prevent seeding -The body’s background radiation is measured by placing the gamma probe in 1-2 neutral sites on the body such as the right shoulder or the right clavicle -The previously removed fatty tissue is measured by the gamma probe. The probe is kept facing upward to avoid measuring any background radioactivity -Finally, the removed parathyroid is measured on the upward facing gamma probe. If the measured radioactivity of the parathyroid tissue is at least 20% higher than the body’s background radiation, it is suggestive that the removed tissue is indeed an adenoma. -Blood is drawn intraoperatively at both 10 and 20 minutes after parathyroid removal in order to confirm successful removal of the offending adenoma. The modified Miami criteria is greater than 50% drop from baseline levels and within the normal range. -Strap muscles are reapproximated using a single interrupted 3-0 vicryl suture -The deep dermal layer is closed with interrupted 3-0 vicrly sutures followed by a running subcuticular monocry suture and a sterile adhesive placed over the closed wound.
hypercalcemia >10.5 mg/dL 24-h Urinary calcium >350 mg/day Episode of life-threatening hypercalcemia Creatinine clearance decreased by ≥30 % Nephrolithiasis Age <50 years Osteitis fibrosa cystica Osteoporosis Neuromuscular symptoms
-Just prior to operating, the patient should have their preoperative PTH levels measured and the 99mTc-sestamibi radiomarker is administered intravenously.
-The performing physician must evaluate the patient to ensure that primary hyperparathyroidism is the true etiology of their hypercalcemia. This includes ruling out other possible causes such as secondary/tertiary hyperparathyroidism or familial hypocalciuric hypercalcemia, or from a medication. -The performing physician can select from multiple different imaging modalities to attempt to visualize the adenoma preoperatively such as ultrasound, 4D CT, or MRI.
Due to the risk of damage to the Recurrent Laryngeal nerve, candidates for MIRP should have their vocal cord mobility accessed prior to operating.
1. Cox M.D., Stack B.C. (2017) Minimally Invasive Radioguided Parathyroidectomy. In: Stack, Jr. B., Bodenner D. (eds) Medical and Surgical Treatment of Parathyroid Diseases. Springer, Cham

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