Locating, rescecting, and confirming removal of abnormal parathyroids with intraoperative testing: A subspecialty skill
The parathyroids are two small areas of paired gland tissue to the left and right of the thyroid gland in the neck. Among other functions, they control calcium levels in the blood.
Disorders of the parathyroid glands are uncommon but include hyperparathyroidism, in which one or more parathyroid glands are overactive (enlarged and overproductive) and thus parathyroid hormone (PTH) levels are too high, causing elevated blood levels of calcium. This disorder can cause a long list of disparate symptoms. Primary hyperparathyroidism can bring on such nonspecific symptoms as low energy, memory or concentration problems, and a general sense of feeling poorly. The associated high blood calcium levels can also cause escalating problems, including bone conditions, stones, and cardiac or gastrointestinal symptoms. Thus, parathyroid conditions are usually identified not just by evaluating patient symptoms but also through blood tests.
In addition, surgery is the only way to directly treat these conditions, as there is no drug therapy available for parathyroid overactivity. Surgery removes the overproductive parathyroid gland or glands, curing the disease. Patients can retain normal endocrine function without needing to retain all four parathyroid hormones.
Locating Problem Parathyroids
In almost all cases of parathyroid disease, only one of the four glands is abnormal. (In rare cases, of parathyroid hyperplasia, all four glands are enlarged, and the surgeon will remove all but a portion of one, so that patients are cured of parathyroid-hormone overproduction but still retain parathyroid endocrine function.) An overactive parathyroid gland is swollen and larger than normal parathyroids. While they are considered to be tumors, enlarged parathyroid glands are almost always benign adenomas.
In a previous era, abnormal parathyroids (or "parathyroid tumors") were more difficult to locate. This necessitated an open surgical exploration of the parathyroid areas, as the first operative step in the surgical procedure, in order to visually locate the enlarged gland(s).
Today, a nuclear medicine scan of the parathyroid area can show the surgical team where the abnormal parathyroid tissue is located prior to surgery. This type of scan is called an sestamibi scan, after the tiny protein molecule that attaches to active parathyroid tissue in this test and that is injected into the blood stream as the first step in the test. Bound to a safe, low-level radioactive substance, this protein accumulates in abnormal parathyroid tissue and is then easily imaged by a detector that creates a nuclear-medicine image of any activity present in the parathyroids. (Note that normal parathyroid glands become dormant when blood calcium is high; thus, in the presence of an abnormal parathyroid gland, normal parathyroid glands are inactive and will not absorb the radioactive material and, therefore, do not become radioactive and, as a result, remain invisible on the scan.) An overactive parathyroid will show up as bright, radioactive spot.
Having an in-house nuclear-medicine staff that is experienced and skilled in performing these scans is important, as is having an endocrinologist who knows how to use this test. Aria's respected specialists in its Department of Radiology provide sestamibi scans for Aria's endocrine surgeons. This technique of locating an abnormal gland preoperatively with a radioactive scan makes possible the minimally invasive parathyroid surgery available today.
Minimally Invasive Parathyroid Surgery
In minimally invasive parathyroid surgery, the surgeon can make a single small incision (one inch or less) at the location of the abnormal gland and remove it directly, without disrupting other parathyroid or thyroid tissue and with the need for minimal or no exploratory manipulation. This unilateral surgery (surgery to just one side of the parathyroids) offers a number of advantages over the standard open surgery of the past:
• much less dissection of surrounding neck tissue or disturbance of normal parathyroid or thyroid gland;
• quicker operation (less than an hour and often 30 minutes or less);
• less recovery time;
• less chance of complications (such as damage to nerves in the neck);
• and minimal scarring (that normally disappears after six months);
• return to home same day, after the operation.
Confirming Successful Removal
The challenge in parathyroid surgery is confirming that the parathyroid gland targeted for removal has, in fact, been removed, that it has been removed in its entirety, and that no other overactive parathyroid tissue or glands remain. To achieve this without resorting to open, conventional surgery to both sides of the parathyroids (bilateral surgery for visual inspection of all parathyroid glands), endocrine surgeons have used an intraoperative radioactive probe to pinpoint the tissue that has accumulated the sestamibi tracer. The probe served as a small Geiger counter to locate the overactive gland. Since overactive parathyroids remain radioactive for only a few hours after a sestamibi scan, this approach required surgery soon after the initial scan or a repeat of the scan on the day of surgery.
While this intraoperative nuclear mapping approach vastly improved parathyroidectomy and is still used in some endocrine surgery programs, it is not the preferred or most up-to-date approach. Sestamibi scans may not identify all abnormal parathyroid glands, in some cases. Sometimes when PTH levels have not returned to normal when tested after surgery, this has brought the need for repeat scans and repeat operations.
Aria has invested in the laboratory equipment and abilities that permits it to measure parathyroid hormone levels rapidly during surgery, in a test called rapid PTH assay. A drop in PTH levels during the procedure provides a more-dependable and less-invasive indication that all abnormal parathyroid tissue has been removed. Aria endocrine surgeons work closely with Aria pathologists in this capability. A 50-percent or more drop in parathyroid hormone level soon after operative removal of the targeted parathyroid gland means that all abnormal tissue has been removed and that the operation is complete.
In addition, in recent past years, some surgeons retained a portion of the removed parathyroid glands and preserved it by freezing (cryopreservation), in case this tissue was needed for reimplantation at a future time if the patient's parathyroid function was found to be too low following surgery. With the precision offered by intraoperative PTH testing, however, this step is also no longer necessary.
|Traditional Surgery More Difficult to Perform and Undergo
The past standard for parathyroid surgery, in use for most of the last century, is still required for a small percentage of patients and involves a more extensive incision into and manipulation of the neck area (both sides or bilaterally) than with minimally invasive parathyroid surgery. In this operation, surgeons make a larger incision to visually locate and examine all four thyroid glands, in order to determine which is abnormal and remove it. In the past, before the advent of the sestamibi scan, this operation was widely used and was the only option that allowed the surgeon to locate the abnormal parathyroid gland or glands. The surgery always requires general anesthesia and sometimes one or more nights in the hospital.
This standard surgery may still be necessary for patients with abnormal PTH levels but negative sestamibi scans. Bilateral surgery is also necessary for the rare patient whose scan identifies an abnormal parathyroid gland in each side the neck.
The incision for this conventional parathyroid surgery is at least six inches in length and leaves a prominent and permanent scar on the neck. In addition, surgeons undertaking this traditional approach must be highly skilled to avoid damaging small nerves and other delicate structures in the neck. While this operation is generally considered safe and effective, it is requires more time in the operating room and a longer recovery. Fortunately, at medical centers such as Aria –– with the rapid-PTH-assay capability to confirm successful removal of abnormal parathyroid tissue –– the success of minimally invasive surgery is equal to that of the conventional operation.
If removal of the abnormal gland does not decrease PTH levels adequately, this is an indication of additional abnormal parathyroid glands, and the surgical team will convert to an open procedure to explore these additional glands. In addition, if the team determines that the thyroid gland has a nodule or enlargement that must be removed, the surgeon can do so as part of the same procedure. In some cases, this may also mean converting to a traditional, bilateral procedure. Also rarely, additional abnormal parathyroid glands may be located in the chest, requiring further surgery.
What To Expect In Parathyroid Surgery
Most patients who undergo parathyroid surgery will receive general anesthesia. The use of local anesthesia and sedation only for parathyroid surgery is uncommon, and much less common than in thyroid surgery. However, Aria's program offers the possibility of local anesthesia and sedation in some cases where general anesthesia is not optimal because the patient cannot tolerate it for other reasons. (This option of avoiding general anesthesia if necessary in parathyroidectomy is a rare capability and one that requires special experience and skill.) Also, endoscopic video assistance is not normally necessary in parathyroid surgery, but nevertheless may be employed and beneficial in selected cases.
Thyroid surgery normally takes between 30 and 60 minutes, depending on whether more than one gland is explored. The traditional approach requires sutures or clipping of the wound and packing for bandaging the site. But after minimally invasive parathyroid surgery, incisions for Aria patients are closed with a newer method that uses specially developed surgical glue, so that no dressing or drains are required at all. Our staff considers this a safer approach, and other advanced centers have adopted the technique as well.
Minimally invasive surgery is typically an outpatient procedure, with most patients going home within in a few hours of the operation. Traditional surgery almost always means at least a one-night stay in the hospital.
Any patients undergoing parathyroid surgery will experience some soreness in or around the throat, but patients who undergo the minimally invasive procedure will have less discomfort around the external wound. This helps to speed recovery and hasten return to normal daily activities. Patients can typically resume most normal activities the next day, although return to driving or other activities that require turning the head comfortably may take slightly longer.
Find a True Specialist in PT Surgery
Hyperparathyroidism is rare and its treatment thus demands a surgeon with special focus, training, and experience in this area. Patients should find a parathyroid specialist in order to get the most up-to-date treatment for this condition, which means minimally invasive parathyroidectomy with intraoperative PTH testing.
All patients who have hyperparathyroidism should be evaluated for minimally invasive parathyroid surgery. Aria's dedicated endocrine surgery service routinely provides this operation in experienced hands. Aria is one of just a small number of centers in the nation with significant experience performing this surgery. Consulting with our staff provides patients with assurance about whether or not they are candidates for this surgery.