The challenge of the middle mediastinal parathyroid

Video assisted thoracoscopic excision of mediastinal ectopic parathyroid adenomas: a UK regional experience

BACKGROUND

To report the first series of video-assisted thoracoscopic surgery (VATS) resection of mediastinal ectopic parathyroid adenomas (MEPAs) in the UK.

METHODS

A case series of seven cases undergoing VATS between 2004 and 2009 to treat single gland hyperparathyroidism. Methylene blue (MB) was used in 5/7 cases immediately before exploration to identify the adenomas. Carbon dioxide (CO2) up to pressures of 10 mmHg was used safely to deflate the lung in two cases.

RESULTS

There were five women and two men with a mean age of 53 years (range, 27-72 years). Histopathology confirmed successful resection of the parathyroid adenoma in 6/7 cases. There was one conversion to open thoracotomy due to bleeding from the azygos vein resulting from excessive traction. Despite marked MB uptake, this patient proved to have tuberculoid adenopathy and no parathyroid tissue was identified. Postoperative plasma calcium returned to normal in 6/7 patients and parathyroid hormone (PTH) level in 6/7 patients. The median hospital stay was 2 days and there was no mortality in this series.

CONCLUSIONS

MEPAs can be safely resected using VATS with minimal surgical morbidity, short drainage time and short hospital stay. CO2 insufflation and the intraoperative use of MB are safe and help to accurately localise the ectopic adenoma. VATS should be considered as the first-line approach for resection of MEPAs.

Multicenter study of 19 aortopulmonary window parathyroid tumors: the challenge of embryologic origin

BACKGROUND

Ectopic abnormal parathyroid glands are relatively common in the superior mediastinum but are rarely situated in the aortopulmonary window (APW). The embryological origin of these abnormal parathyroid glands is controversial. The purpose of this investigation was to investigate the embryological origin and the surgical management of abnormal parathyroid glands situated in the APW.

METHODS

The databases of patients operated on for primary, secondary, and tertiary hyperparathyroidism at eight European medical centers with a special interest in endocrine surgery were reviewed to identify those with APW adenomas. Demographic features, localization procedures, and perioperative and pathology findings were documented. The embryological origin was determined based on the number and position of identified parathyroid glands.

RESULTS

Nineteen (0.24%) APW parathyroid tumors were identified in 7,869 patients who underwent an operation for hyperparathyroidism (HPT) and 181 patients (2.3%) with mediastinal abnormal parathyroid glands. Ten patients had primary, eight had secondary, and one had tertiary HPT. Sixteen patients had undergone previous unsuccessful cervical exploration. In three patients, an APW adenoma was suspected by preoperative localization studies and was cured at the initial operation. Sixteen patients had persistent HPT of whom 15 were reoperated, resulting in 6 failures. Evaluation of 17 patients who had bilateral neck exploration allowed us to determine the most probable origin of the APW parathyroid tumors: 12 were supernumerary, 4 appeared to originate from a superior, and 1 from an inferior gland.

CONCLUSIONS

Abnormal parathyroid glands situated in the APW are rare and usually identified after an unsuccessful cervical exploration. Preoperative imaging of the mediastinum and neck are essential. The origin of these ectopically situated tumors is probably, as suggested by our data, from a supernumerary fifth parathyroid gland or from abnormal migration of a superior parathyroid gland during the embryologic development.

Thoracoscopic resection of mediastinal parathyroids: current status and future perspectives

The location and removal of ectopic mediastinal glands represents one of the major problems in parathyroid surgery. Minimally invasive surgery for such indications has been evaluated to reduce the high morbidity and long reconvalescence of standard open approaches. The recent introduction of robotic surgical systems may offer new options for this purpose. A literature review of reports on thoracoscopic resections of mediastinal parathyroids is presented. The potential of a robotic surgical system for this indication is discussed. Between 1994 and 2002, 19 groups have reported on thoracoscopic parathyroidectomy in a total of 38 patients. In seven (18%) patients thoracoscopic identification had to be radioisotopically guided. Two (5%) conversions to an open approach were necessary. There were three (8%) moderate complications. Based on available data, video-assisted thoracic surgery (VATS) is a less invasive, effective and safe procedure for the removal of ectopic mediastinal parathyroids and can therefore be recommended as the standard approach. However, preoperative localization of the ectopic gland is a prerequisite. Surgical robotic systems have the potential to make this type of procedure even more accurate and thus safe.

Robot-assisted mediastinal parathyroidectomy

We report the first case of robot-assisted thoracoscopic resection of a mediastinal parathyroid adenoma in the aorto-pulmonary window. Intervention planning was based on preoperative CT-MIBI image fusion, a new imaging modality that enabled reliable and precise localization of the parathyroid. The technique consists of taking MIBI-SPECT and CT separately, using a fixation unit that provides reproducible positioning of the patients head and neck. The data sets are then superimposed upon each other using special software. After the localization process, a minimally invasive operation was performed using the DaVinci operating robot. The procedure proved not only to be feasible but also safe and not time-consuming. The postoperative course was uneventful, and the patient was discharged 4 days postoperatively. Compared to conventional thoracoscopic surgery, the robotic operating system provides better visualization of the operating field and facilitates the movement of the instruments. Precise preoperative imaging enables the careful planning of robot-assisted surgery for ectopic parathyroids located at relatively inaccessible regions such as the anterior mediastinum.

Middle mediastinal parathyroid: diagnosis and surgical approach

We report two cases of middle mediastinal parathyroid ectopia associated with chronic renal disease. In both patients the diagnosis was delayed and prolonged due to the unusual location of the ectopic parathyroid tissue. The surgical approach was in error in 1 patient and corrected during the second procedure. We describe the surgical technique for exposing and excising parathyroid tissue from this area.

[Supernumerary ectopic hyperfunctioning parathyroid gland: a potential pitfall in surgery for sporadic primary hyperthyroidism]

STUDY AIM

The aim of this retrospective study was to report a series of nine patients with a sporadic primary hyperparathyroidism, operated on for an ectopic supernumerary hyperfunctioning parathyroid gland.

PATIENTS AND METHOD

From 1973 to 1998, among a total of 1,307 patients operated on for a primary hyperparathyroidism, 9 (0.69%) had an ectopic supernumerary hyperfunctioning gland. There were six women and three men (mean age: 63 years) with a sporadic hyperparathyroidism. Initial cervicotomy was performed in our institution in 6 cases. The nine patients underwent 19 operations including one through sternotomy. The ectopic parathyroid gland was localized in the eight patients who had preoperative localization studies.

RESULTS

The supernumerary gland was located in the anterior mediastinum (n = 6), in the carotid sheath (n = 2) and within the vagus nerve (n = 1). In three patients, it was found during the initial cervicotomy. In the 6 other patients, it was found in the course of a reoperation. With a mean follow-up of five years, all the patients were biochemically cured. One patient had a permanent recurrent nerve palsy and a definitive hypoparathyroidism.

CONCLUSIONS

The low incidence of an ectopic supernumerary hyperfunctioning parathyroid gland in sporadic hyperparathyroidism does not justify the routine use of preoperative localization studies and intra-operative quick parathormon assay. During an initial conventional cervicotomy the search for a 5th gland is highly recommended when 4 normal glands have been found in the neck. This research should also be performed in case of multi-glandular disease.

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.

Angiographic ablation of mediastinal parathyroid adenomas: local experience and review of the literature

PURPOSE

To evaluate local experience with a modified technique for angiographic ablation of mediastinal parathyroid adenomas.

PATIENTS AND METHODS

Three patients with likely mediastinal parathyroid adenomas that had single feeding arteries underwent attempted arteriographic ablation with a slow continuous infusion of contrast medium. Patients were closely monitored for symptoms and calcium dynamics immediately postprocedure and then on a long-term outpatient basis.

RESULTS

All three patients were cured (follow-up 22 to 68 months) with no long-term complications.

CONCLUSION

Percutaneous angiographic ablation with contrast medium is a reasonable alternative for patients with hyperparathyroidism due to a mediastinal adenoma who can be treated in centers with well-trained interventional radiologists.

Causes of failed primary exploration and technical aspects of re-operation in primary hyperparathyroidism

Hypercalcemia was corrected in 62 (90%) of 69 patients after re-operation for primary hyperparathyroidism during a mean follow-up of 6.3 years. Failed primary exploration was mainly due to inadequate visualization of the pathological parathyroid glands, often in association with misleading or absent peroperative histology. Other causes included seeding of parathyroid adenoma tissue, truly recurrent adenomas, and recurrent hyperplasia, especially in patients with multiple endocrine neoplasia type 1. A considerable number of parathyroid glands missed at the primary operations were subsequently found in essentially normal positions. Ectopic superior glands were most frequently positioned para-esophageally or retro-esophageally, while abnormally placed inferior glands were generally situated within or close to the thymus. Glands in 3 patients were dissected from around the large vessels in the mediastinum. Concomitant thyroid procedures during the primary operation yielded few abnormal parathyroids and made the re-exploration considerably more difficult. We suggest a semilateral approach and caudal identification of the recurrent laryngeal nerve to reduce the hazards of difficult parathyroid re-operations. Mediastinal exploration may require total removal of the thymus and careful dissection of the middle mediastinum.

Primary hyperparathyroidism in the 1990s. Choice of surgical procedures for this disease

Many advances have occurred in recent years in the diagnosis, localization, and treatment of primary hyperparathyroidism. Several different operative choices for primary hyperparathyroidism also have been proposed--a unilateral approach versus the standard bilateral parathyroid exploration. The unilateral approach is based on the concept that if an enlarged parathyroid gland and a normal gland are found on the first side of the neck that is explored, then this is an adenoma and the second side should not be explored. Only if both glands on the initial side are recognized to be abnormal is the second side explored. The theoretical advantages of this unilateral approach are a decrease in operative morbidity rates--hypoparathyroidism and nerve injuries--and a decrease in operative time. Furthermore, proponents argue that if persistent hyperparathyroidism occurs, the second side can be easily explored because it was previously untouched. In the hands of several expert parathyroid surgeons, excellent results have been achieved. However, the unilateral approach has a number of disadvantages. It places considerable pressure on the surgeon and pathologist, for they have only one parathyroid gland other than the large one to examine. There is a significant potential risk of missing double adenomas or asymmetric hyperplasia because the second, ipsilateral parathyroid gland may appear normal or near normal in these conditions. This could lead to an increased incidence of persistent or recurrent hyperparathyroidism. Furthermore, a significant reduction of operative time may be questioned, especially when the time for performing special fat stains, which often are performed with unilateral explorations, is added. Finally, even if the intent is to perform a unilateral exploration, a bilateral exploration will be necessary about half of the time. The authors strongly recommend a bilateral parathyroid exploration for all patients undergoing an initial parathyroid operation. In cases of adenoma, bilateral visualization of normal parathyroid glands and careful biopsy of only one of them will minimize hypoparathyroidism. This operative approach will lead to better results, especially for the less experienced parathyroid surgeon.

Mid-mediastinal parathyroid lesions: preoperative localization and surgical approach in two cases

Although hyperfunctioning mediastinal parathyroid lesions that require median sternotomy or thoracotomy for removal are occasionally present, the majority are located in the anterior mediastinum closely associated with the thymus. Only eight cases of ectopic hyperfunctioning parathyroid tumors in the middle mediastinum have been reported. We experienced two cases of either persistent or recurrent hyperparathyroidism in which abnormal parathyroid tissue was located in the aorticopulmonary window. One of the patients had a parathyroid adenoma and the other had metastatic lesions of parathyroid carcinoma. In both cases, thallium scanning proved useful in identifying the lesions while computed tomography scan was effective for mediastinal three-dimensional localization. In one case, single photon emission computed tomography imaging with thallium proved beneficial for both identification and localization of the middle mediastinal lesion. The surgical approach used in both cases was different. In one case, left thoracotomy was performed, after which the ligamentum arteriosum was divided, and an adenoma anterior to the left main bronchus and posterior to the left pulmonary artery removed. In the other case, two metastatic tumors of parathyroid carcinoma anterior to the right main bronchus and posterior to the right pulmonary artery were resected through a median sternotomy and opening of the pericardium.