The undescended "parathymus". An occasional cause of failed neck exploration for hyperparathyroidism

Avoiding Complications of Thyroidectomy: Preservation of Parathyroid Glands

Preservation of functional parathyroid glands during thyroidectomy and central neck surgery is crucial to avoid the common but serious complication of hypoparathyroidism. The first requirement is a solid foundational knowledge of anatomy and embryology which then enables the surgeon to use meticulous anticipatory dissection with identification and preservation of blood supply to the parathyroids. When preservation of blood supply is not possible, autotransplantation should be performed. New technologies harnessing the natural phenomenon of parathyroid autofluorescence to detect parathyroid tissue and indocyanine green to perform angiography may lead to improved outcomes with low risk to patients.

Comparative Study of Parathyroid Identification Techniques Using Zuckerkandl's Tubercle Versus Parathyroid Arterial Supply as Intra-Operative Markers

Thyroid surgeons should be able to identify factors that prevent parathyroid damage. The aim of the study was (i) to compare the effectiveness of using Zuckerkandl's Tubercle (ZT) versus superior thyroid artery (STA) and inferior parathyroid artery (ITA) as markers for identification of superior and inferior parathyroid glands and (ii) to demonstrate a series of detailed, logical and orderly operative steps to identify ZT during thyroidectomy operation. This 1-year prospective observational study was carried out in the Department of Otolaryngology in a tertiary medical institute. Out of 36 cases of thyroidectomy, parathyroid identification in Group A was based on STA and ITA and in Group B was based on ZT. The surgical steps, parathyroid location, preservation and its anatomical relations were noted. The mean age in Group A and Group B was 38.8 years and 44.9 years respectively with 77.4 and 62.5% SPT identified above the intersection of RLN and ITA respectively. On left side 62.5% SPT were  located at 2 o'clock position and 50% at 10 o'clock location in right side. In Group A, 60.7% of IPT glands were related close to ITA while in Group B it was 44.4%. Group B reported a higher rate of successful identification and preservation (93.75%). ZT greatly improved the reliability for localising and preserving the parathyroid glands during thyroidectomy. SPT is usually found to lie cranial to ZT, above the intersection of RLN & ITA and behind RLN whereas IPT is variable and lies below the intersection.

Main Surgical Principles and Methods in Surgical Treatment of Primary Hyperparathyroidism

The only curative treatment for primary hyperparathyroidism (pHPT) is surgery. The most important factors that increase the success rate of a parathyroidectomy are the establishment of the correct diagnosis and the surgeon's good knowledge of anatomy and embryology. The lower parathyroid glands develop from the dorsal portion of the third pharyngeal pouch, and the upper parathyroid glands from the fourth pharyngeal pouch. Humans typically have 4 parathyroid glands; however, more than 4 and fewer than 4 have been observed. Typically, the upper parathyroid glands are located in the cricothyroid junction area on the posterolateral portion of the middle and upper third of the thyroid, while the lower parathyroids are located in an area 1 cm in diameter located posterior, lateral, or anterolateral to the lower thyroid pole. Ectopic locations of parathyroid glands outside the normal anatomical regions due to the abnormal migration during embryological development or acquired ectopy due to migration of enlarged parathyroids are not uncommon. There are various surgical techniques to treat HPT; however, 2 main surgical options are used: bilateral neck exploration (BNE) and minimally invasive parathyroidectomy (MIP). While there are open, endoscopic, and video-assisted MIP (MIVAP) approaches, most often an open lateral MIP technique is used. In addition, endoscopic or robotic parathyroidectomy methods performed from remote regions outside the neck have been reported. Although currently MIP is the standard treatment option in selected patients with positive imaging, BNE remains the gold standard procedure in parathyroid surgery. In 80% to 90% of patients with pHPT, a pathological parathyroid gland can be detected with preoperative imaging methods and MIP can be applied. However, the pathological gland may not be found during a MIP procedure as a result of false positive results. The parathyroid surgeon must also know the BNE technique and be able to switch to BNE and change the surgical strategy if necessary. If the intended gland is not found in its normal anatomical site, possible embryological and acquired ectopic locations should be investigated. It should be kept in mind that MIP and BNE are not alternatives to each other, but rather complementary techniques for successful treatment in parathyroid surgery.

Ectopic parathyroid adenoma in the soft palate: a case report

Background

Ectopic parathyroid adenomas can occur in numerous anatomic locations. While ectopic parathyroid adenomas can rarely occur in the pharyngeal region, this has not previously been described in the soft palate.

Case presentation

We report the first case of ectopic parathyroid adenoma within the soft palate. A 59 year old woman presented with hyperparathyroidism. She remained persistently hyperparathyroid after initial parathyroidectomy. Repeat exploration for a lesion suspicious on PET-CT for an ectopic parathyroid adenoma in the parapharyngeal region was unsuccessful in treating the hyperparathyroidism. An ectopic adenoma in the soft palate was eventually discovered. Removal through a transoral approach was successful in treating the hyperparathyroidism.

Conclusions

Ectopic parathyroid adenomas can occur in various anatomical locations that may be missed even with the use of the various imaging modalities. The soft palate should be added to the list of possible ectopic locations high in the neck.

Undescended parathyroid adenomas as cause of persistent hyperparathyroidism

BACKGROUND

Undescended glands are a rare cause of primary and secondary hyperparathyroidism (HPT), but they are more common, however, among patients with recurrent HPT or those who have undergone a failed initial cervical exploration. The currently development of more precise noninvasive imaging techniques has improved the results of preoperative diagnosis of these ectopic lesions.

METHODS

The operative reports of patients undergoing parathyroidectomy at our institution were reviewed to identify patients with an undescended parathyroid gland adenomas. Demographic, clinical, imaging and surgical variables were recorded.

RESULTS

Three patients were included: 2/598 parathyroidectomies performed for primary HPT and 1/93 performed for secondary HPT. One case is presented as jaw tumor syndrome (JTS). All the patients had undergone at least one operation before the definitive focused surgery and represented 6% of our parathyroid reoperations. No significant complications and no recurrences were observed in the long-term follow up.

CONCLUSIONS

Accurate preoperative localization of these lesions was possible with noninvasive studies. High cure rate is possible through selective approach when accurate preoperative localization. Thorough knowledge of parathyroid embryology and meticulous surgical technique are essential, particularly in patients with previous unsuccessful explorations.

Undescended parathyroid adenoma

Undescended parathyroid adenomas are rare, representing 0.08% of all parathyroid adenomas; however, they make up 7% of the underlying cause of failed cervical exploration in patients with persistent primary hyperparathyroidism. A 43-year-old woman with no significant medical or family history presented with fatigue and was diagnosed with primary hyperparathyroidism; however, preoperative imaging including sestamibi scan and ultrasound was unable to identify the hyperfunctioning gland. She underwent a neck exploration and hemithyroidectomy and partial parathyroidectomy with failure of resolution of her disease. Subsequent work up including a CT of the neck demonstrated a 1.9 cm mass adjacent to the left submandibular gland. This was removed with postoperative normalisation of the patient's serum calcium and parathyroid hormone levels.

Adenomas of cervical maldescended parathyroid glands: pearls and pitfalls

BACKGROUND

Missed parathyroid adenoma (PTA) is the commonest cause of persistent hyperparathyroidism. Although many are subsequently found in well-described locations, some are found in unusual regions of the neck. This paper presents the combined experience of three large tertiary endocrine surgery centres with maldescended PTA (MD-PTA).

METHODS

Patients were recruited from the endocrine surgical databases of three tertiary endocrine surgery units. Patients with PTA found >1 cm above the superior thyroid pole or other cervical locations as a result of abnormal or incomplete descent were included for analysis.

RESULTS

MD-PTA was identified in 16 patients out of a total of 5241 patients who had undergone parathyroidectomies in the 7-year study period (incidence 0.3%). Seven (44%) patients had minimally invasive parathyroidectomy, while nine (56%) had bilateral neck exploration. The mean excised gland weight was 750 + 170 mg. Cure was achieved in all patients with a minimum follow-up of 6 months. The locations of MD-PTA in this study included submandibular triangle, retropharyngeal space, carotid sheath (at carotid bifurcation and intravagal), parapharyngeal space (superior to thyroid cartilage or superior thyroid pole) and cricothyroid space.

CONCLUSIONS

Despite their rare occurrence, incompletely or abnormally descended PTAs can be encountered by any surgeon who performs parathyroidectomies. It is important to develop a strategy to systematically locate these glands. High cure rates can still be achieved with minimally invasive parathyroidectomy if confident preoperative localization is available. A sound knowledge of embryology and a thorough exploration also facilitate an overall high success rate with open exploration.

Techniques for parathyroid localization with ultrasound

Four-gland parathyroid exploration has been the gold standard for parathyroid surgery until recently. Emphasis is now placed on minimally invasive and focused parathyroidectomy. In conjunction with functional sestamibi scanning, ultrasonography permits accurate localization of enlarged parathyroid glands in the vast majority of patients with hyperparathyroidism. Consequently, ultrasound technology applied to parathyroid pathology facilitates directed surgical therapy and minimally invasive applications. As such, ultrasonography holds great promise as a tool that enables cost-effective and advanced patient care.

Parathyroid sonography: imaging and intervention

This article reviews the role of high-resolution sonography as an imaging modality for the diagnosis and treatment of patients with parathyroid disease. Included is a discussion of sonographic anatomy and technique, disease processes of the parathyroid glands and their sonographic appearances, preoperative imaging, and the use of sonography as a guide for diagnostic and therapeutic intervention in parathyroid disease.

Persistent primary hyperparathyroidism caused by adenomas identified in pharyngeal or adjacent structures

Abnormalities in the normal migration of the parathyroid glands during embryological development of the head and neck may result in considerable variability in the location of parathyroid tissue. Ectopic parathyroid adenomas present diagnostic and technical challenges and are frequently the cause of persistent primary hyperparathyroidism (HPT) after unsuccessful initial parathyroid surgery. We report a series of eight patients with persistent primary HPT who had adenomas in rare and unusual locations associated with various pharyngeal structures. Four were located within the epineurium of the vagus nerve at or above the level of the carotid bifurcation, and four were located within the paranasopharyngeal space or oropharynx. Noninvasive and invasive preoperative imaging studies were crucial in localizing the neoplasms in these patients and permitted the use of a direct surgical approach, resulting in cure in all patients and a low complication rate. The location of parathyroid glands in high pharyngeal and cervical structures is a consequence of anomalous or arrested descent through developing pharyngeal structures and illustrates the remarkable spectrum of ectopic parathyroid adenomas that occur secondary to this phenomenon.

Undescended superior parathyroid gland: a potential cause of failed cervical exploration for hyperparathyroidism

BACKGROUND

The undescended inferior parathyroid gland is a well-established although infrequent embryologic abnormality resulting in an ectopically located gland usually associated with thymic tissue and is found most commonly within the carotid sheath at the level of the carotid bifurcation. Embryologically undescended superior glands (either normal or enlarged), clearly above the level of the upper pole of the thyroid gland and found within or in approximation to the lateral pharyngeal wall, have not been previously described.

METHODS

The locations of all parathyroid glands at the time of cervical exploration were carefully examined as to embryologic origin in a combined experience of more than 3000 patients with primary or secondary hyperparathyroidism.

RESULTS

Five patients had enlarged abnormal glands located within or in close approximation to the pharyngeal wall. All were above the upper pole of the thyroid gland. Two were identified at reoperation on the basis of localization studies. One gland was found after resection of a massive concomitant cervical goiter. The other two were found after an extensive search for a superior gland.

CONCLUSIONS

Undescended superior glands are extremely rare (0.08%). They are located within or in approximation to the pharynx above the level of the thyroid gland with an unusual blood supply, which supports an embryologic rather than acquired cause for their ectopic location.

Initial failure of surgical exploration in patients with primary hyperparathyroidism

To determine the causes of failures of cervical exploration for primary hyperparathyroidism, we reviewed 892 patients operated on by one surgeon from 1953 to 1990. Twenty-seven patients (3%) remained hypercalcemic or developed hypercalcemia within 6 months of surgery. Of these, five patients had one adenoma removed initially; at reoperation, three patients had a second adenoma that was successfully removed, whereas the other two patients had hyperplasia and required subtotal parathyroidectomies. No enlarged parathyroid glands were identified in 22 patients. Eventually, six patients became normocalcemic spontaneously, seven patients underwent re-exploration with a successful outcome in all but one case, two patients had ectopic hyperparathyroidism associated with carcinoma elsewhere, and seven patients refused reoperation and remain hypercalcemic. The failure rate of surgical exploration for primary hyperparathyroidism can be reduced by systematically exploring all four parathyroid glands. All abnormal parathyroids should be removed with histologic verification. When no abnormal glands are found, localization studies should be performed before re-exploration.

Undescended parathyroid adenoma: an important etiology for failed operations for primary hyperparathyroidism

From July, 1982 to April, 1989, a total of 145 patients with persistent or recurrent primary hyperparathyroidism (HPT) were explored; 105 patients had an adenoma as the cause of HPT, and in 9 patients (9%), the abnormal gland was located at or superior to the carotid bifurcation (undescended parathyroid gland). These 9 patients had 14 prior explorations for HPT including 4 median sternotomies and 5 thyroidectomies. Each of the 9 patients was symptomatic of HPT, including bone disease in 8 of 9 patients and renal stones in 4 of 9 patients. Seven patients had an undescended parathyroid adenoma correctly localized preoperatively by ultrasound (n = 5), angiography (n = 5), venous sampling (n = 1), or computed tomography scan (n = 4). These 7 patients with accurate preoperative localization were explored by an incision anterior to the sternocleidomastoid muscle high in the neck that avoided the previous operative field and allowed rapid resection of the parathyroid adenoma. In the 2 patients who did not have accurate preoperative localization, the undescended adenoma was found after long tedious exploration including median sternotomy in 1 patient. Each patient (n = 9) who had an undescended parathyroid adenoma removed was cured of hypercalcemia, and 5 patients required postoperative 1,25-dihydroxy vitamin D3 for hypocalcemia. We conclude that undescended parathyroid adenomas comprise a significant proportion (9%) of adenomas during reoperations for persistent HPT.(ABSTRACT TRUNCATED AT 250 WORDS)

Parathyroid cyst: report of case in the mediastinum

Though a rare lesion a parathyroid cyst is of clinical significance because it usually mimics a thyroid cyst and can be associated with hyperparathyroidism. The cyst can be ectopic with location in the lateral neck or in the mediastinum and therefore constitutes a differential diagnosis to a branchial or thymic cyst. A case report of a mediastinal parathyroid cyst without hyperparathyroidism is presented. Fine needle aspiration with parathyroid hormone assay on the cyst fluid will reveal the correct diagnosis. Surgical removal of the cyst is recommended, and hyperparathyroidism should be considered.

The reasons for persistent hypercalcaemia after cervical exploration for presumed primary hyperparathyroidism

Of 500 consecutive patients who underwent cervical exploration for presumed primary hyperparathyroidism, 461 (92.2 per cent) were cured, as judged by an immediate return of serum calcium levels to normal. Thirty-nine patients (7.8 per cent) had persistent hypercalcaemia after the initial operation. The clinical profiles, operative and pathologic findings, surgical procedures performed and subsequent management of these 39 patients were reviewed. At reevaluation, 4 patients were noted to have been cured of their hyperparathyroidism. Twenty-one patients had persistent hyperparathyroidism: in 6, all 4 parathyroid glands had not been identified at the initial operation and in 15, hypercalcaemia persisted after the identification of 4 glands. One patient had recurrent hyperparathyroidism after the removal of a 720 mg adenoma and the identification of 3 normal parathyroid glands. Nine patients had nonparathyroid causes for the hypercalcaemia: 2 had occult malignant neoplasms, 6 had benign familial hypocalciuric hypercalcaemia and 1 had immobilization hypercalcaemia. In 4 patients the reason for the persistent hypercalcaemia remained unclear. We suggest a schema that may be used as a guideline in the investigation and management of patients with persistent hypercalcaemia after primary neck exploration for presumed hyperparathyroidism.

Lessons of parathyroid reoperations

The case histories of the 23 patients in this series demonstrate the importance of a systematic approach to parathyroid surgery. Ligation of the superior thyroid vessels and mobilization of the upper pole of the thyroid are often necessary to find the superior parathyroid glands that are located on the posterior surface of the thyroid. Devascularization of the thyroid gland does not occur with this maneuver because of abundant collateral circulation from the inferior thyroid artery and tracheal vessels. Normal appearing parathyroid glands should not be resected because this procedure does not treat hypercalcemia and may leave the patient with insufficient parathyroid tissue if an adenoma is found at a later date. Bilateral cervical exploration [35,36] is performed before resection of any abnormal appearing parathyroid tissue. Patients may also have supernumerary parathyroid glands [16], especially in the inferior cervical and superior mediastinal areas that are associated with the thymus [37,38].

[Reoperations for persistent and recurrent hyperparathyroidism (author's transl)]

The results of 26 reexplorations in 24 patients with primary hyperparathyroidism are reported. In 20 patients the disease was classified as persistent, in 3 as recurrent. The diagnosis was confirmed by measurement of calcium and phosphate in serum and urine and by serum-PTH. All patients were symptomatic. Localisation of the tumors was possible by following the embryology and topographical anatomy of the parathyroids during surgery; localization was not as successful in the various preoperative investigations used. Postoperatively, no patient was hypercalcemic. The success rate was 100% for 21 patients, with a follow-up time of more than 6 months. Use of cryopreservation and autotransplantation of the endocrine tissue proved very advantageous; this technique was performed successfully in two of ten hypocalcemic patients and still may be considered in another three patients.

Reoperation for primary hyperparathyroidism

The reasons for failure of the initial exploration and the results of reoperation were analyzed in 53 patients with a diagnosis of primary hyperparathyroidism, 29 of whom were referred after initial operations elsewhere. Seventy-nine reoperations were performed. Sternotomy was used in 15 patients, and in retrospect was necessary in only 5. There was no operative mortality. The reasons for initial failure were incorrect diagnosis in 6 patients, true recurrence in 4 and persistent disease in 43. Persistence was caused by surgical failure in two thirds and pathology failure in one third. Of 47 patients reoperated on for hyperparathyroidism, 39 (83 percent) were cured, a rate warranting this type of surgery. Analysis of a long-term series of initial operations demonstrates a persistence rate of 5 percent (24 of 461) and a recurrence rate of 1 percent (4 of 461) in this disease. The need for reoperation was les than 1 percent over the recent 5 year period.

Reoperation for primary hyperparathyroidism

Between 1960 and April, 1980, 302 patients were explored for primary hyperparathyroidism at Emory University Hospital. Seventeen of these 302 patients had undergone initial surgical exploration elsewhere, and were referred for persistent hypercalcemia. Of the 285 patients who were operated on at our institution, 14 subsequently had persistent hypercalcemia, and two had recurrent hypercalcemia. Twenty-eight of these 33 patients had had re-exploration, and 23 (82%) are now normocalcemic. Twenty-eight abnormal glands were found; 22 (79%) were retrievable via the neck and six (21%) required sternotomy. Of those glands removed via the neck, nine were in a near normal location and 13 in a subnormal or abnormal location. The causes of initial surgical failures were abnormally located glands, in ten patients, insufficient explorations of the neck in eight patients, hyperfunctioning parathyroid remnants in three patients, inadequate plans for hyperplasia in two patients, and carcinoma in one patient. In 57% of our patients who underwent successful re-exploration, the glands were correctly localized before operation by angiographic examination or selective venous sampling for parathormone. Thorough exploration and obtainment of biopsy specimens of all parathyroid glands are recommended in order to keep initial failures to a minimum. If reoperation is required, localization using CT scan, angiography and selective venous sampling are recommended.