How is parathyroid surgery performed?
Figure 6: Intra-operative photo
The traditional technique for parathyroid surgery was bilateral neck explorationBilateral neck exploration - An operation where the surgeon examines all four parathyroid glands., in which the surgeon identifies all four of the parathyroid glands and determines which glands are diseased based on the size and appearance of the glands. This technique has been proven over time to be very safe and effective when performed by an experienced surgeon. However, since 80-85% of patients with primary hyperparathyroidism have only one gland that is abnormal, many surgeons have shifted to doing a more limited and less invasive operation in patients thought to have a high likelihood of having a single abnormal gland. This more limited approach is often referred to as a focused parathyroidectomyFocused Parathyroidectomy - An operation where the surgeon examines and removes just the hyperactive parathyroid gland and not all four parathyroids. . In a focused parathyroidectomy, the surgeon goes after and removes only the hyperactive gland that is identified on pre-operative localizing testsLocalizing tests - Any test that is used to find or "localize" abnormal parathyroid gland(s). The most common are sestamibi scan and ultrasound.. The term "minimally invasive parathyroid surgery" is often used to refer to focused parathyroidectomy, but really can be used for any parathyroid operation done through a very small incision. The length of the operation will vary depending on multiple factors including patient characteristics, whether a single gland is removed or if an exploration of both sides of the neck with removal of multiple glands is performed, and whether the operation is a first time surgery or a re-operation. Depending on the complexity of the surgery, the operation may last as little as 20 minutes or as long as several hours.
There are many variations in how parathyroid surgery is performed based on surgeon preference. When deciding on a surgeon, it is important to remember that the type of technique used is far less important than the surgeon's personal experience and success rate. For example, whether the surgeon uses a radioguided technique or pre-operative imaging-based technique makes little difference when compared to the experience of the surgeon. Research has proven that the chance of being cured and of not having a complication after parathyroid surgery depends on the experience of the surgeon. 62 In general, a surgeon should do more than 50 parathyroid operations a year to be considered an expert. Every surgeon has developed an approach based on their own experiences and resources that works well for them, so please discuss with your surgeon what approach they will use. Below is a description of some of the more commonly used techniques.
2. Bilateral Neck Exploration
Bilateral exploration was the traditional surgical approach to parathyroid surgery and may also be referred to as open parathyroidectomy, standard parathyroidectomy, 4 gland exploration, or conventional parathyroidectomy. This approach has proven over time to be highly successful with cure rates of 95% or greater when performed by an experienced surgeon. In order to be successful, the surgeon must identify all four parathyroid glands. In the past each parathyroid gland was biopsied to confirm that all glands were identified. However, due to the risk of injuring the blood supply to the parathyroid glands, biopsies of normal appearing glands is no longer recommended. Pre-operative localization and special intraoperative techniques (such as intraoperative parathyroid hormone - or PTH - testing or radioguidance) are not required, but may be used to guide the surgeon. Traditionally a bilateral exploration was performed through a 5-7 inch incision. However, most surgeons are now able to do this operation through a much smaller 1 1/2 -2 inch incision. The incision is usually located in the middle to lower portion of the neck and is curved to match the skin folds in your neck. The muscles are separated to expose the thyroid gland and the thyroid gland is retracted to expose the parathyroids. Temporary low calcium levels after surgery may occur in as many as 25% of patients 63. Low calcium levels after surgery can cause numbness and tingling in your lips, fingers, and toes. If this occurs it can usually be treated with calcium pills and the symptoms resolve within 15-30 minutes. (see What are the risks of parathyroid surgery?)
3. Focused parathyroidectomy
Focused exploration consists of "going after" a single abnormal gland and removing it. The surgeon will not plan on exploring the rest of the neck to find the other parathyroid glands. This technique may also be referred to as directed parathyroidectomy, minimally invasive parathyroidectomy or targeted parathyroidectomy. There are many different ways to perform a focused parathyroidectomy and these include image-guided, radioguided, and video-assisted techniques. Since the surgeon will not attempt to look at all four parathyroid glands in the operating room, it is crucial to perform pre-operative localizing tests. (see Localization) A patient may be considered for focused parathyroidectomy if a pre-operative localization reveals a single abnormal gland (or two abnormal glands on the same side of the neck). Many surgeons will also use intraoperative parathyroid hormone (PTH) monitoring to confirm that there is no other hyperactive parathyroid tissue. (see Intraoperative PTH Monitoring) Other adjuncts such as radio-guidance or video-assistance may also be used. Focused parathyroidectomy is typically performed through a smaller incision than the bilateral exploration, usually 1/2 or 1 1/4 inches long and can be performed through either a medial or lateral approach. For the medial approach the incision is typically 3/4 to 1 1/2 inches in size and is placed in the center of the neck. The muscles are separated along the midline and the thyroid is exposed and retracted medially. For the lateral approach, a 1/2 to 1 1/4 inch incision is made on the side of the neck over the muscle. The muscles are separated to expose the carotid artery and the edge of the thyroid gland. The thyroid is retracted medially and the carotid artery is retracted laterally to expose the space where the parathyroid glands lie. This approach works very well for glands that are located deep in the neck. In either method, once the abnormal gland is removed, many surgeons will use the intraoperative PTH test to confirm that all abnormal tissue has been removed. The cure rate of focused parathyroidectomy is approximately 95 to 98% and is the same as for bilateral neck explorationBilateral neck exploration - An operation where the surgeon examines all four parathyroid glands. 63-65. There are several potential advantages of focused parathyroidectomy over a bilateral neck exploration including: smaller incision size, improved cosmetic result, shorter operative time, creation of less scar tissue, and fewer problems with low calcium levels after surgery. The incidence of symptomatic low calcium levels has been shown to be reduced from 25% in a bilateral exploration to 7% or less with focused parathyroidectomy 63.
4. Radioguided Parathyroidectomy
Radioguided parathyroidectomy is a type of focused parathyroidectomyFocused Parathyroidectomy - An operation where the surgeon examines and removes just the hyperactive parathyroid gland and not all four parathyroids. and involves giving a small injection of Tc-99m sestamibi (the same agent used for the sestamibi scan, just a smaller dose) the morning of surgery. The surgeon then uses a handheld gamma probe (essentially a miniature Geiger counter) in the operating room to identify the hyperactive gland during surgery. The probe can also be used to help place the incision directly over the abnormal parathyroid gland as well as to lead the surgeon to it. The gamma probe is also used to confirm that the tissue that has been removed is indeed parathyroid tissue. The benefits of the intraoperative gamma probe have been debated. The greatest benefit appears to be in potentially reducing operative time when it is a reoperation, finding an ectopic parathyroidEctopic parathyroid - a parathyroid gland that is not found in the usual location next to the thyroid, and identifying the times the sestamibi scanSestamibi scan - Nuclear medicine test where a small amount of radioactive material is injected into a vein and an X-ray is taken. incorrectly identifies a thyroid nodule as a parathyroid gland. The major downsides to using this technique include increased cost from the extra resources needed and additional radiation exposure. Although this technique can be useful, many surgeons feel that experience and a thorough knowledge of parathyroid anatomy make it unnecessary.
5. Video-assisted parathyroidectomy
Video-assisted parathyroidectomy is also known as minimally invasive video-assisted parathyroidectomy and endoscopic parathyroidectomy. Several techniques of video-assisted parathyroidectomy have been described using approaches from the middle of the neck or the side of the neck. The typical incision for this technique can be as small as 1 1/4 inches. The main benefit of the video-assisted technique is that it provides greater magnification and may allow the surgeon to do the operation through a smaller incision. The downsides to this procedure include a longer operating time, the need for additional equipment, and the fact that it cannot reach certain areas of the neck. The safety and cure rate seem equal to other forms of focused parathyroidectomyFocused Parathyroidectomy - An operation where the surgeon examines and removes just the hyperactive parathyroid gland and not all four parathyroids. . 66, 67
6. Surgical options for four gland hyperplasia
Multiple abnormal parathyroid glands are found in 15- 20% of patients. Up to 10% of patients with primary hyperparathyroidism will have four hyperactive glands, a situation called four gland hyperplasia. If all four glands are abnormal then the treatment options are a subtotal parathyroidectomy (removal of 3 or 3 1/2 glands) or a total parathyroidectomy with autotransplantation (removal of all parathyroid tissue and placing a part of a parathyroid in the forearm or neck muscle). The autotransplanted parathyroid will grow a new blood supply and will typically start working in 4-6 weeks.