Robot-Assisted Excision of Ectopic Mediastinal Parathyroid Adenoma
Alexander PH Chan, MBBS,
Innes YP Wan, FRCSEd,
Randolph HL Wong, FRCSEd,
Michael KY Hsin, FRCSEd,
Malcolm J Underwood, FRCS
Division of Cardiothoracic Surgery, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
Malcolm J Underwood, FRCS, Tel: +852 2632 2629, Fax: +852 2637 7974, Email: mjunderwood{at}surgery.cuhk.edu.hk, Department of Surgery, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China.
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ABSTRACT
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Robot-assisted excision of an ectopic parathyroid adenoma in the superior mediastinum was performed in a 57-year-old man. The mass was located by methoxyisobutylisonitrile scan and computed tomography. Identification of the ectopic parathyroid adenoma was facilitated by the 3-dimensional images of the da Vinci robotic system, and resection was achieved using EndoWrist instruments. Robot-assisted excision of parathyroid adenoma located in the relatively inaccessible superior mediastinum proved to be feasible.
Key Words: Parathyroid Neoplasms • Robotics • Thoracic Surgery • Video-Assisted
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INTRODUCTION
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The introduction of commercially available robotic surgical systems has broadened the arena of minimally invasive thoracic surgery.1,2 The 7-degree movement of the robotic EndoWrist (Intuitive Surgical, Mountain View, CA, USA) enhances precise tissue dissection within a restricted operative field. The surgeon’s movements can be downscaled, and tremor can be filtered. The 3-dimensional images on the surgeon’s console further enhance visual definition. We report a case of successful mediastinal parathyroidectomy performed using the da Vinci robotic system (Intuitive Surgical).
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CASE REPORT
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A 57-year-old man with endstage renal failure presented with persistent tertiary hyperparathyroidism despite a parathyroidectomy being performed. His parathyroid hormone level remained high at 170 pmol·L–1 (normal, 1.7–9.2 pmol·L–1). A methoxyisobutylisonitrile scan showed an ectopic gland located within the right paratracheal space at the sternal notch level (Figure 1A
). Computed tomography of the thorax showed a 1.3 x 1.1 x 1.3-cm soft tissue nodule, corresponding to the site identified by methoxyisobutylisonitrile scan, between the right innominate artery and superior vena cava, on axial view (Figure 1B). On coronal and sagittal views, the parathyroid tissue was located above the left brachiocephalic vein and below the right innominate artery (Figure 1C and 1D). We have learned from our video-assisted thoracic surgery experience that identification and resection of an ectopic parathyroid gland embedded within the thymus is difficult. The decision was made to undertake robot-assisted thoracic surgery (RATS) for excision of the ectopic parathyroid gland. Under general anesthesia with double-lumen endotracheal tube intubation for selective single-lung ventilation, the patient was positioned with his right side up at 30 degrees by placing silicon gel behind his right shoulder and upper back. His right arm was positioned to the side of the operating table, with the shoulder slightly extended. The surgical cart with the robotic arms was positioned over the left side of the table. A 30-degree upward stereo endoscope was inserted via a 15-mm incision in the 5th intercostal space at the midaxillary line. Two access ports of 5–7 mm were created in the 3rd intercostal space on the anterior axillary line and the 5th intercostal space on the mid-clavicular line. The 2 robotic arms of the da Vinci system were attached to the 2 access ports. The right lung was deflated, and CO2 insufflation was started at 10 mm Hg through the camera port, to enhance visualization of the operative field by washing out diathermy smoke. Cadiere forceps with EndoWrist action were used through the left port. Electrocautery blades with EndoWrist action were used via the right port, acting as a dissecting instrument. No auxiliary port was required. Robot-assisted thoracoscopic examination of the right hemithorax was carried out. There was a need to mobilize the thymus and expose the left brachiocephalic vein to access the ectopic parathyroid gland. Dissection was started at the right lower pole of the thymus, anterior to the right phrenic vein, and the thymus was mobilized. The left lobe of the thymus was mobilized and the ectopic parathyroid gland was identified (Figure 2). There were large feeding vessels from the thymus and brachiocephalic veins, which were clipped and divided. The ectopic parathyroid gland was delivered through the video port. The parathyroid hormone level dropped to 1.3 pmol·L–1 on the day after the operation. The total operative time was 210 min, of which 30 min was required for positioning the surgical cart and robotic arms. There was no postoperative complication, and the chest tube was removed on postoperative day 1. The patient was discharged 3 days postoperatively. Histological examination confirmed parathyroid adenoma.
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Figure 1. (A) Methoxyisobutylisonitrile scan showing ectopic parathyroid tissue (white arrow) just right of the midline at the sternal notch level. The previous right thyroidectomy with intact left thyroid gland (black arrow) is also shown; (B) Axial computed tomography showing the ectopic parathyroid adenoma (white arrow) located behind the sternal notch, with a feeding vessel (grey arrow) from the thymus anteriorly; (C) Coronal and (D) sagittal computed tomography showing the ectopic parathyroid gland (arrowed) located below the right innominate artery and above the left brachiocephalic vein.
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DISCUSSION
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The identification and subsequent resection of ectopic parathyroid glands in the mediastinum using traditional video-assisted thoracic surgery or a transcervical approach might pose difficulties with regard to the restricted area, small tumor size, similar appearances of fat lobules and thymus, and close proximity to surrounding important vascular structures. It is well known from open and conventional thoracoscopic surgery that ectopic parathyroids can often be identified only using radionuclide guidance.3,4 RATS provides an alternative option to overcome these difficulties.
Bodner and colleagues2 and Profanter and colleagues5 reported robotic procedures for resection of ectopic mediastinal parathyroid adenomas in the aortopulmonary window. In both cases, dissection within this delicate area was found to be accurate and safe at all stages of the operation. Differentiation of the ectopic parathyroid gland from surrounding thymic or adipose tissue can be enhanced with the 3-dimensional endoscopic image on the surgeon’s console, with better color resolution and contrast. Precise dissection of the ectopic gland can be achieved with the robotic EndoWrist system. However, the lack of tactile feedback remains the biggest hurdle for the development of RATS in the field of general thoracic surgery.
RATS is a new approach and surgeons experienced in video-assisted thoracic surgery have to undergo training to acquire this new skill. We started our robotic thoracic surgical programme with simple thymectomies 2 years ago, and moved on to resection of thymic tumors, followed by chest wall tumors. There was a steep learning curve, in particular, the time required to set-up the robotic arms, but running costs and consumables are the main concerns. We think that there is still room for enhancement of the robotic surgical system before RATS can become popular within the general thoracic surgical arena. However, RATS excision of mediastinal ectopic parathyroid adenoma is feasible.
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REFERENCES
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- Bodner J, Wykypiel H, Wetscher G, Schmid T. First experiences with the da Vinci operating robot in thoracic surgery. Eur J Cardiothorac Surg 2004;25:844–51.[Abstract/Free Full Text]
- Bodner J, Wykypiel H, Greiner A, Kirchmayr W, Freund MC, Margreiter R, et al. Early experience with robot-assisted surgery for mediastinal masses. Ann Thorac Surg 2004;78:259–65.[Abstract/Free Full Text]
- Onoda N, Ishikawa T, Yamada N, Okamura T, Tahara H, Inaba M, et al. Radioisotope-navigated video-assisted thoracoscopic operation for ectopic mediastinal parathyroid. Surgery 2002;132:17–19.[Medline]
- Ott MC, Malthaner RA, Reid R. Intraoperative radioguided thoracoscopic removal of ectopic parathyroid adenoma. Ann Thorac Surg 2001;72:1758–60.[Abstract/Free Full Text]
- Profanter C, Schmid T, Prommegger R, Bale R, Sauper T, Bodner J. Robot-assisted mediastinal parathyroidectomy. Surg Endosc 2004;18:868–70.[Medline]
Asian Cardiovasc Thorac Ann 2010;
18:65-67
© 2010 by SAGE Publications
DOI: 10.1177/0218492309354218
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ABSTRACT
INTRODUCTION
