Minimally Invasive Parathyroid Surgery
While some surgeons may focus on the advances in high-tech specialized tools when discussing minimally invasive surgery, an important key to the advent of these new endocrine procedures has been the development of better diagnostic imaging procedures, for example, Sestamibi scanning and high-resolution ultrasound for parathyroids and high-resolution CT scanning for adrenals. Once these new imaging procedures provided a road map for finding small parathyroid, thyroid and adrenal nodules, it was only a matter of time before the development of less invasive surgical techniques to remove them.
Evolution of Treatment
In the mid-1990s, it was discovered that intravenously administered Sestamibi illuminated abnormal parathyroid glands. This led to the development of a thin, Sestamibi-detecting radioactive probe, which was designed as a guide for minimally invasive parathyroid detection and resection. Thanks to this advancement, large incisions for full visualization of all four parathyroid glands were no longer necessary. Most hyperparathyroidism is caused by a single parathyroid tumor that is easily located when the Sestamibi probe is introduced through a carefully placed 1-inch surgical opening in the neck.
Rapid Intra-Operative Parathyroid Hormone Test
Unfortunately, 10 to 15 percent of patients with hyperparathyroidism have more than one enlarged parathyroid gland, and these patients will not be cured by the radio-guided probe technology. The solution for the multiple parathyroid tumor dilemma arrived in the late 1990s with the development of a rapid parathyroid hormone test that could easily be deployed in the operating room with a turnaround time of less than 10 minutes. Using this analysis before and five to 10 minutes after the removal of parathyroid tumors, it was demonstrated that a 50-percent drop in blood parathyroid hormone levels after tumor resection produced a surgical cure in almost all circumstances. Thus, the multiple gland problem was largely solved by using the rapid intra-operative parathyroid hormone test as a gold standard for cure. If parathyroid hormone blood levels do not drop more than 50 percent after resection of the first parathyroid tumor, the surgeon continues to search for more abnormal parathyroid tissue in other likely locations.
Combination of Treatments
At Memorial Center for Integrative Endocrine Surgery, there is a strong emphasis on high resolution ultrasound screening (performed by R. Mack Harrell, MD, our endocrinologist) to locate enlarged glands prior to surgery. Then, in the operating room, both the Sestamibi probe and rapid parathyroid hormone test techniques are used in the effort to maximize the surgical success rate.
As with all neck surgeries, complications of minimally invasive parathyroidectomy may include vocal cord paralysis due to accidental damage to the recurrent laryngeal nerve (which lies close to the parathyroids), bleeding, and low blood calcium if too much parathyroid tissue is removed. If all the abnormal parathyroid tissue is not removed, the blood calcium will remain high after the surgery and the patient will not be cured from the hyperparathyroidism. Studies have shown that minimally invasive radio-guided parathyroid surgery (MIRP) has a 95 percent success rate.
Read an article on the importance of collaboration between an ultrasonographer and endocrine surgeon to perform minimally invasive radio-guided parathyroid surgery, written by R. Mack Harrell, MD, and David N. Bimston, MD.
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