Overview of Parathyroid Minimally Invasive Surgery
In the past, doctors used to explore both sides of the neck to treat a condition called hyperparathyroidism, which is when the parathyroid glands produce too much hormone. However, we now know that a single adenoma, or benign tumor, is the cause in 85% of hyperparathyroidism cases.
With the help of advanced medical technology, we can now locate these adenomas more accurately. This has led to the development of a less invasive surgical approach to treating hyperparathyroidism. Nowadays, this method is becoming a standard of care – a treatment that experts accept as appropriate, widely used, and based on evidence.
Anatomy and Physiology of Parathyroid Minimally Invasive Surgery
The inferior and superior parathyroid glands are the names for small glands in your body that come from different parts of your neck area when you’re developing. There are 4 of these glands, each weighing about 20 to 40 grams, and they sit behind the thyroid, another gland in your neck.
The superior glands, or the ones on top, are usually found about 1 cm above a network of blood vessels and nerves in the middle of the thyroid. The inferior glands, or the ones on the bottom, can be found in different locations because they grow with another part of your body called the thymus. Even so, they tend to be located in the lower third of the thyroid.
Both of these glands get their blood supply from an artery called the inferior thyroid artery, which comes from a larger blood vessel in your neck. In some people, about 20 to 45% of cases, the upper glands can also receive blood from a different artery called the superior thyroid artery).
Why do People Need Parathyroid Minimally Invasive Surgery
When a patient has hyperparathyroidism that’s causing symptoms like kidney problems, stomach and intestine issues or muscle and nerve disease, a doctor may recommend surgery. Hyperparathyroidism is a condition where the parathyroid glands produce too much parathyroid hormone, which can lead to high levels of calcium in the blood.
If a patient has hyperparathyroidism but doesn’t have symptoms, the National Institute of Health (NIH) has provided some guidelines to help doctors decide if surgery is the right step. The NIH recommends surgery if a patient has:
- Blood calcium levels 1.0 mg/dL higher than the normal limit
- Passed more than 400 mg of calcium in their urine in 24 hours
- Kidney function decreased by 30%, measured by creatinine clearance
- A bone mineral density T score less than -2.5 SD at any site, which suggests a loss of bone strength that could lead to fractures
- Age younger than 50 years
The type of surgery used to treat hyperparathyroidism is called a parathyroidectomy, which involves removing the overactive parathyroid glands. This helps bring the patient’s calcium levels back to normal, reducing their symptoms.
When a Person Should Avoid Parathyroid Minimally Invasive Surgery
Before a less invasive type of parathyroid gland surgery (minimally invasive parathyroidectomy, or MIP for short) can be done, doctors need to locate the gland in the body. If the exact location isn’t clear, or if tests are inconclusive, it might not be safe to try this kind of surgery. Instead, a more traditional surgery might be needed.
There are other situations when a less invasive surgery is not the best option. If a person has a family history of hyperparathyroidism (over-active parathyroid glands), which is sometimes seen in disorders like the MEN syndromes, the problem tends to be caused by all four glands being over-active (4-gland hyperplasia) rather than just one. In this case, a broader approach is needed.
A less invasive surgery is also not suitable if a person has parathyroid cancer, another disease of the thyroid, or has had radiation treatment to the neck. In these cases, a more extensive kind of surgery (radical resection) is usually needed.
Lastly, if a person has had surgery on their neck before, it doesn’t necessarily mean that they can’t have a less invasive surgery. This is considered a relative contraindication, meaning it might make the surgery less ideal, but it doesn’t rule it out entirely.
Equipment used for Parathyroid Minimally Invasive Surgery
There are several tools that doctors may use during surgery to assist them. One of these tools is a high-definition ultrasound. This device can be used alongside pre-surgery studies to further understand the area they will operate on. It can also be used during surgery with a procedure called Fine Needle Aspiration (or FNA for short), to look at any areas within the body that may not be normally seen.
A tool routinely used during an operation is the frozen section analysis. This method quickly freezes and studies the removed tissue during surgery to ensure that it is indeed the expected parathyroid tissue. However, it can’t tell the difference between an adenoma (a noncancerous tumor) and a condition called multi-gland hyperplasia, where many glands have increased in size. But, it’s extremely good (over 99% reliable) at telling parathyroid tissue apart from other tissue types.
Another important technique used during the operation involves testing PTH (or Parathyroid Hormone) levels. This is done to confirm that the overactive tissue has been successfully removed. Since PTH hormone levels decrease by half every 2 to 4 minutes, doctors use a guideline (referred to as the Miami criterion) stating that the PTH level should drop by 50% within 10 minutes of the gland being removed. For this reason, blood samples are taken before the surgery, right after the gland has been removed, and again at 5 and 10 minutes after the gland removal process.
Preparing for Parathyroid Minimally Invasive Surgery
Before undergoing a ‘MIP’ (Minimally Invasive Parathyroidectomy – a type of operation that removes a part of the parathyroid gland), it’s important to do a special test to locate exactly where your parathyroid is. This helps your surgeon plan the operation and improves its success rate.
The best way of locating the parathyroid is by using a method called scintigraphy with technetium-99m (this is a type of tracer that can be seen on body scans). In this test, the tracer is put into your body and pictures – either flat 2D pictures or 3D pictures (SPECT) – are taken to determine where the tracer has gathered, which will be your parathyroid gland.
Another way is dual-radioisotope imaging, where two different tracers are used – technetium and thallium. These tracers are taken up differently by the thyroid and parathyroid, which helps to identify each of them. However, this method can require specialized software, take a longer time, and provide limited views of the area.
Alternative methods like CT scans (system of X-rays to get detailed body images), MRI (uses strong magnets and radio waves to produce detailed images of your body), and ultrasound (high-frequency sound waves to create images of your body), are available but might not show the parathyroid as well.
How is Parathyroid Minimally Invasive Surgery performed
A MIP, or Minimally Invasive Parathyroidectomy, is a surgical procedure involving small cuts and specialized techniques to remove one or more of your parathyroid glands. This procedure might use general anesthesia, which means you’ll be completely asleep, or a local anesthesia that numbs your neck area while you’re sedated. During the surgery, you’ll be positioned with your neck slightly raised — a bit like you’re sitting up in bed reading — and a roll placed under your shoulders for support. However, they’ll make sure your neck isn’t bent back too far.
Different types of MIP are available depending on the specific situation. These include the OMIP (open), MI-RP (radio-guided), VAP (video-assisted), and EP (purely endoscopic) methods.
An Open MIP is quite common. The surgeon will make a small cut of about an inch long in the middle or side of your neck. After opening up the skin a bit, they will gently move aside your muscles to reach the thyroid. The abnormally functioning gland will be very carefully removed without damaging nearby tissue.
A Radio-guided MIP uses a special tool guided by a radioactive substance injected into your body before the surgery to find and remove the abnormal gland. This ensures that no more than 20% of the radioactive substance remains in the neck after the operation, indicating successful removal of the problematic gland.
In contrast, Video-assisted MIP utilizes a small camera and surgical instruments inserted through a small cut above your breastbone. This method might be a good choice if your abnormal gland is very small and if additional thyroid-related work is expected. However, this procedure requires two supporting assistants, and will likely take more time if the problematic gland is larger.
Endoscopic MIP, meanwhile, is performed entirely through several small incisions with a viewing tube called an endoscope. Whether performed through the middle or side of the neck, this method involves inflating the working area with gas and working beneath the skin for maximum precision. However, this procedure needs more skill to perform and requires a longer learning curve for the surgeon.
Rest assured, your surgeon will decide the best approach for your condition based on their experience, your health condition, and the size and location of your abnormal gland.
Possible Complications of Parathyroid Minimally Invasive Surgery
Even though traditional surgery to remove the parathyroid glands (a surgery called a parathyroidectomy) already has low rates of problems, a less invasive approach can lower these risks even further. Compared to the more traditional surgery, the less invasive method has fewer complications (1.2% compared to 3.1%), higher success rates (99.4% compared to 97.1%), cuts the surgery time in half (from 2.4 hours to 1.3 hours), reduces the hospital stay by almost 7 times (from 1.64 days to 0.24 days), and saves around $2,700 for each procedure.
However, any surgery can have complications. One serious problem could be damaging a critical part of the throat called the recurrent laryngeal nerve. This nerve controls parts of our voice box and throat, so any damage can lead to voice changes (hoarseness) or even difficulty breathing. Damage to this nerve can happen during surgery in several ways, such as direct injury or heat damage. The good news is, if the damage is due to pressure or stretching the nerve, it may heal by itself over one to two months. But if there’s no improvement after 6 to 12 months, the damage is likely permanent.
Another possible issue after surgery is a condition called permanent hypoparathyroidism, which affects the body’s calcium levels. Temporary low calcium levels can happen in up to half of the people after this surgery, but long-lasting hypoparathyroidism is rare, happening in less than 1% of cases. This condition is usually more common when all four parathyroid glands have to be taken out. However, as the less invasive techniques are typically used for removing just one gland, this problem is much less likely.
What Else Should I Know About Parathyroid Minimally Invasive Surgery?
Thanks to recent technological progress, doctors can now perform many procedures in a less invasive manner. This is true in many medical specialties and for various health conditions. An example can be found in Minimal Incision Parathyroidectomy (MIP), a less invasive surgery to remove the parathyroid glands.
With the help of these modern techniques, there’s a lower chance of complications, better chances of successful treatment, and the surgical scars are less noticeable. These significant benefits encourage surgeons to advance their skills in using these less invasive procedures.