Introduction
Parathyroid glands are endocrine glands that secrete parathyroid hormone. They are four in number and are located behind the thyroid. The parathyroid hormone (PTH) regulates the blood's calcium, phosphorous, and vitamin D levels. Apart from building healthy bones, calcium plays an important role in blood clotting (in an injury), muscle contraction, normal heart rhythms, and nerve impulses to the brain. To perform all these functions, the body absorbs calcium from our food, stores 98 percent of it in the bone, and circulates the rest in the blood. The kidneys filter out the excess calcium.
When the calcium level in the blood decreases, the parathyroid gland releases the PTH. This hormone does multiple things-
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It will facilitate the reabsorption of calcium from the kidneys, which were initially destined to be excreted out.
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It will activate the inactive vitamin D, essential for calcium absorption from the intestine.
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It will also initiate osteoclast activity in the bone. Osteoclasts are a type of cell that resorb the calcium-containing bone and release the calcium into the blood.
These functions are only useful when they occur at an appropriate time and speed. The excess PTH will lead to hyperparathyroidism, and reduced PTH causes hypoparathyroidism.
What Happens in Hyperparathyroidism?
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In hyperparathyroidism, the gland produces excess PTH, which in turn will stimulate more calcium reabsorption from the kidneys, intestine, and bone. As a result, the activities performed by normal calcium will move at a warp speed which is not ideal.
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The heart rhythms and the nerve impulses go faster; unnecessary clots form within the blood flow, calcium stones form in the kidneys, and uncontrolled muscular spasms. Excess PTH also causes osteoporosis because of the osteoclasts' activity, which continuously resorbs the bones for extra calcium.
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The parathyroid glands will make excess PTH if there is an adenoma (benign tumor) or a parathyroid carcinoma in the gland. One or two of the four glands often become abnormal and cause hyperparathyroidism symptoms, which will have to be removed by parathyroidectomy.
What Are the Symptoms of Hyperparathyroidism?
Excess PTH causes the following symptoms:
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Polydipsia- Unquenchable thirst leading to continuously drinking water.
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Polyuria- Excess urination due to polydipsia.
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Nephrolithiasis- The formation of stones in the kidney due to excess calcium absorption is known as nephrolithiasis.
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Hypercalciuria- It is a condition where the calcium in the urine is more than 400mg/dL (normal is 100-300 mg/day).
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Impaired Renal Function- The amount of urine filtered reduces to less than 60 mL/minute (normal is more than 90 mL/min).
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Osteoporosis- Due to the continuous osteoclast activity, the bone density reduces, making the bones easily susceptible to fracture.
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Pancreatitis- Hyperparathyroidism does not directly cause inflammation of the pancreas, but it is more of a secondary complication.
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Peptic Ulcer and Gastroesophageal Reflux- Excess calcium levels in the blood increase gastrin (a hormone that stimulates gastric secretions) and acetylcholine resulting in gastroesophageal reflux and peptic ulcer.
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Neurocognitive Dysfunction and Neuropsychiatric Symptoms- Lethargy, confusion, memory impairment, depression, paranoia and hallucinations are a few neurological symptoms of excess PTH.
The symptoms depend on the pathology of the parathyroid gland and the duration of hyperparathyroidism; for example- primary hyperparathyroidism is always caused due to an adenoma or a carcinoma, and secondary hyperthyroidism is a physiological response to hypocalcemia, and tertiary hyperparathyroidism is a combination of secondary hyperparathyroidism and excess secretion of PTH.
What Is Parathyroidectomy?
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The surgical removal of abnormal parathyroid glands is known as parathyroidectomy; it is the preferred treatment for primary and tertiary hyperparathyroidism. Secondary hyperparathyroidism can be managed through medication and diet.
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In traditional parathyroidectomy, the surgeon uses an open neck approach; an incision is made in the neck, followed by exploring the underlying muscles and thyroid gland until the parathyroid glands are localized; then, all four parathyroid glands used to be removed for preventive measures. However, recent technologies like ultrasound (help in the localization of parathyroid without any surgical exploration), radio-guided surgery, endoscopic-assisted parathyroidectomy, and intraoperative assessment of PTH levels have been adopted to facilitate a minimally invasive parathyroidectomy.
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While these are all developments in the instrumentation of parathyroidectomy, the approach is still made through the neck, which leaves a visible scar after the operation. To prevent this, surgeons have developed transoral parathyroidectomy, which allows the removal of the hyperplastic parathyroid gland through the mouth.
What Is Transoral Parathyroidectomy?
It is a scarless alternative to the traditional parathyroidectomy, where the surgeon accesses the parathyroid glands through the mouth.
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Technique- After sufficiently anesthetizing the patient, the surgeon places a 10-millimeter incision inside the lower lip at the lingual frenum. This incision is extended laterally into the vestibule, followed by hydro dissection of the underlying muscles in the chin, submental region, and neck.
Three trocars (one for the camera and two for working ports) are inserted; this helps to locate and separate the parathyroid gland from the underlying trachea. Once the enlarged parathyroid gland is excised, a custom-made endo band is inserted, and the extracted specimen is placed in it. Once hemostasis is achieved, the trocars are removed, and sutures are placed in the oral mucosa. There is no need for any drain or tube other than post-operative instructions and pain medication.
What Are the Post-operative Instructions for Transoral Parathyroidectomy?
Post-op, the patient is put on a liquid diet for two days and released on the third day with a prescription of prophylactic antibiotics and nonsteroidal anti-inflammatories. At home, they are advised to maintain good oral hygiene (gentle brushing twice, gargling with mouthwash, and avoiding sweets).
What Are the Complications of Transoral Parathyroidectomy?
Traditional parathyroidectomy has complications like bleeding and hematoma, recurrent laryngeal nerve injury, hypoparathyroidism, and hypocalcemia, but these are not seen in transoral parathyroidectomy. This is because, unlike the traditional approach, the transoral technique does not require extensive exploration to locate the parathyroid glands. It only removes the abnormal parathyroid gland; the healthy glands are kept in a place that produces sufficient PTH to maintain normal calcium levels.
Conclusion
Transoral parathyroidectomy is a well-tolerated procedure with a minimal recurrence rate. Preoperative investigations like computed tomographic (CT) scans and scintigraphic images play an important role in the localization of the parathyroid glands. The procedure's success depends on the patient's selection and the surgeon's experience.
