Parathyroidectomy Surgery Technique: Expert Advice for Optimal Outcomes

[Dr. Dipan Desai]
Then how do you go about elucidating what type of disease they have, whether it's an adenoma or four gland disease in terms of imaging studies or any other evaluation prior to surgery?

[Dr. David Goldenberg]
There are studies that say that actually when, and this is counterintuitive, that if people have multigland disease that their parathyroid hormone is actually lower. All of my patients will get at least one imaging modality if they've not had it done beforehand. If I'm convinced that the patient has primary hyperparathyroidism and their localization imaging or images do not localize anything, then that's the assumption that we go on that they have multi-gland disease.

[Dr. Dipan Desai]
What are the imaging studies that you prefer?

[Dr. David Goldenberg]
Because of the way patients are referred to us from the outside and they come into a tertiary medical center, oftentimes the patient comes with something already done. Sometimes it's adequate and sometimes it's not. If I'm the person working the patient up, I go with a four-dimensional CAT scan. I've been doing this for a while and this has evolved over time. First, I did Ultrasounds in the office and then I was doing CT scans and now, I believe that the four-dimensional CAT scan is the most accurate for my practice. I don't typically do double scans as proof of the disease. There are those who do, if they say that if you have two concurrent modalities that show this, then you know you have your diagnosis. I personally don't do this. I go with the imaging in the lab.

[Dr. Ashley Agan]
Can you elaborate on what a 4D CT scan is?

[Dr. David Goldenberg]
A 4D CT scan is a lot less cool than it sounds. When I first heard of it, I thought it would be spinning and holograms. There's none of that. It's basically a thinly sliced CAT scan with multiple phases of arterial and venous contrast and some nifty software which allows you to differentiate between parathyroid adenomas, lymph nodes, the thyroid gland. It also gives you some really nifty imaging of the arterial blood supply to the parathyroids and that also helps find adenomas.

We have to remember that the size of a normal parathyroid is the size of a grain of rice and there is no imaging modality to date that can see a normal parathyroid. That being said, a parathyroid adenoma can be maybe the size of a raisin. They can be bigger too, but oftentimes they're not all that impressive when you get them out. It's nice to wear loops because they look really big to you when you're taking them out, but they really are not that big.

[Dr. Dipan Desai]
Can you talk a little bit about the pros and cons of the alternative imaging modalities, either in-office Ultrasound or SPECT CT scans?

[Dr. David Goldenberg]
Sure. Ultrasound is wonderful. As long as the adenoma is at the threshold or above the threshold of detection, size-wise, then it's great. You see a hypoechoic nodule. If it's an inferior parathyroid, typically you'll see it, it's extra thyroidal, it's hypoechoic. Upper parathyroid adenomas are easier to-- You can see, again, extra thyroidal hypoechoic, and then you see a thyroid tissue above it on the longitudinal scan, great. The problem is the two enemies of Ultrasound are air and bone.

If it's below the clavicles, if it's an elderly person, if it's below the manubrium, if it's behind the airway, you're not going to see it. A SPECT scan, PA SPECT scan is injection of technetium and has a different washout time. Nowadays most people are doing a SPECT CT scan fused where you have functional anatomic data at the same time superimposed one upon the other. The technetium stays behind in the adenoma when it washes out of the thyroid gland and the CAT scan shows you anatomically where it is and you put them together and you get a nice little area in either orange or blue that's illuminated very nicely.

It will not see very small adenomas, and it also is a little weaker in flat adenomas. This is anecdotal, this is what I've seen when I was doing, if the adenoma is flattened against the back of the thyroid gland, sometimes it won't be seen. Like I said, the four-dimensional CAT scan has been great. If someone comes in with a scan and it's non localizing, I certainly will get them another scan in our institution. It's important if you're doing this kind of surgery that you feel comfortable reading these scans yourself, and I do, I do get radiology's input, but they're quite a few times where they've said there's nothing there and I thought there was, and in the end, surgery proves whether you're right or wrong.

[Dr. Dipan Desai]
Okay. Obviously sometimes these cases can be tricky where you go in thinking you have a single localized adenoma, or you start doing your four gland exploration and one of the parathyroid didn't read your wonderful textbook and is hiding. Can you talk us through some of the steps and places you go looking for a parathyroid that's not where it's supposed to be?

[Dr. David Goldenberg]
Sure. Someone once told me if it was easy, it wouldn't be fun. As you well know the pan-parathyroid surgery can be incredibly quick and easy and simple. There are times it can be very frustrating because where is it? It is paramount that the parathyroid surgeon understands the embryology of the parathyroid glands because that's the key to where the missing gland is if something is missing. I think that's what you're asking, correct?

[Dr. Dipan Desai]
Yes.

[Dr. David Goldenberg]
The lower parathyroids have a longer descent and therefore they're more apt to get lost. That's just the way it is in medicine or an anatomy embryology and the most common place for a lost lower parathyroid is in the mediastinum together with the thymus and other places that they can be, would be, in the carotid sheath and even inside the thyroid gland. The upper parathyroid, and I have seen those get lost. They also are in the carotid sheath. They're usually retropharyngeal or retroesophageal.

I'm not talking about case reports where they're in the submandibular gland or some really really strange place. Depending which parathyroid is missing, if you're looking for them and every patient is, should be consented for, even if it's a focused parathyroidectomy, every patient is consented for a parathyroid exploration and possible hemithyroidectomy, which is the last place you look, if you are missing a gland and you've looked in the mediastinum, you've dissected the mediastinum you've looked in the carotid sheaths and you're still missing a gland, then we've all seen intra thyroidal parathyroid glands. Most of the intra thyroidal parathyroid glands are in the capsule. They're not really deep in the substance and sometimes you can actually see it, but sometimes it's actually in the substance of the gland.

[Dr. Ashley Agan]
How common is it for it to be in the gland?

[Dr. David Goldenberg]
It's not common. More often you'll see it inside the capsule, but outside the gland like inside the thyroid capsule, but not really in the substance but that also is not all that common.

[Dr. Ashley Agan]
Yes. If you're not finding it you should not be too quick to say, oh, it's probably in the thyroid.

[Dr. David Goldenberg]
No, you have to. If it's a lower, you really do need to dissect the upper mediastinum like you would a central compartment lymph node dissection, and you pull up the thymus like a magician pulling scarves out of a hat and that's the most common place that you would find it. I have seen them in the sheath and I've seen uppers behind the esophagus as well. It happens, the more you do, the more often you're going to see these things and I guess those are the ones that take a little bit more clinical acumen.

[Dr. Dipan Desai]
When you're dissecting out either the central neck compartment or looking in your thyroid gland, are you relying on your pathologist or is it still a visual examination?

[Dr. David Goldenberg]
Oh, I will absolutely rely on my pathologist at that point in time. That's a perfect example of when you need the help of the pathologist. Now Dipan, I'm sure you know this because you do this all the time. When you see a parathyroid adenoma, there it is, it looks like a little piece of liver. It has a certain look to it. Here we go again with food, but sometimes it's hard to tell. For example, Hashimoto's thyroiditis is incredibly common.

Hashimoto's thyroiditis comes with a lot of these little round lymph nodes and sometimes it can be confusing. It's not out of the realm of possibility that your patient has Hashimoto's thyroiditis and they have hyperparathyroidism. Then sometimes you are looking at a whole bunch of little grapes. and you have to make sure that this is in fact, the parathyroid. You just didn't remove an inflamed lymph node. Yes, we definitely would rely on the pathologist if I'm not sure or if I want to differentiate thyroid from parathyroid. Absolutely.