Minimally Invasive Parathyroidectomy: the Australian Experience

Transcription

1 MIP#final 31/3/03 Symposium Minimally Invasive Parathyroidectomy: the Australian Experience Leigh Delbridge, University of Sydney Endocrine Surgical Unit, Royal North Shore Hospital, Sydney, New South Wales, Australia. Minimally invasive parathyroidectomy (MIP) was introduced into Australia after endocrine surgeons agreed that it should only be undertaken in the context of a feasibility study or controlled trial, and under the auspices of the Australian Safety and Efficacy Register of New Interventional Procedures Surgical (ASERNIP-S). Feasibility of endoscopic-assisted parathyroidectomy was studied at Royal North Shore Hospital (RNS) and 49 cases were completed. Subsequently, the technique of a focused lateral approach using a 2-cm incision placed directly over the site of the localized adenoma was developed and has now become the standard technique for the unit. To date, 357 MIPs using the focused lateral approach have been performed with a 1.5% rate of negative neck exploration and a permanent recurrent laryngeal nerve palsy rate of 0.8%. The use of intraoperative rapid measurement of parathyroid hormone (PTH, IO-QPTH) as an assessment of completeness of resection of abnormal parathyroid tissue has been replaced by simply measuring PTH levels 30 minutes postoperatively, a technique that is more cost-effective, and which still allows same-day discharge whilst avoiding false-positive results with IO- QPTH. The introduction of MIP appears to be a factor in the increasing number of referrals for parathyroid surgery. [Asian J Surg 2003;26(2):76 81] Introduction Increasing numbers of parathyroid procedures are being performed worldwide. 1 Indeed, in some countries, the increase appears to be exponential. 2 There are several apparent reasons for this change. In a recent editorial in the New England Journal of Medicine, Utiger recommended parathyroidectomy for nearly all patients with primary hyperparathyroidism based on the dual view that most patients with primary hyperparathyroidism probably have symptoms and that changes in surgical technique have made surgical treatment simpler and faster than in the past. 3 With respect to the first reason given, it is now recognized that parathyroidectomy is likely to benefit patients with a multitude of symptoms, including reduced bone mineral density or osteoporosis, kidney stones, non-specific neuromuscular symptoms including fatigue, lethargy and muscle weakness, mental changes, cardiovascular disease and diabetes In addition, even patients who, by all criteria, would be considered to be asymptomatic have been shown to have an improved sense of wellness following parathyroidectomy. 12 The introduction of MIP appears to be another possible reason for the progressive increase in referrals for parathyroidectomy. The various techniques reported have included a full endoscopic approach with gas insufflation, 13,14 video-assisted approaches, and the direct focused approach using a small cervical incision. 18 A variety of techniques have been introduced to ensure removal of all abnormal parathyroid tissue, including the rapid intraoperative measurement of parathyroid hormone (PTH, IO-QPTH) 19 and the intraoperative nuclear probe. 20 These techniques mean that parathyroidectomy can now be offered as a 1-hospital-day only, local anaesthetic procedure, with a small incision, minimal complications and a success rate equal to the previous gold standard of open four-gland exploration. 21 Despite these apparent advantages, there has always been the concern that the introduction of MIP was a marketdriven exercise solely aimed at promoting a minimally Address reprint requests and correspondence to Dr. Leigh Delbridge, Professor and Head of Surgery, Royal North Shore Hospital, St. Leonards NSW 2065, Australia. leighd@med.usyd.edu.au Date of acceptance: 20 th January, Elsevier. All rights reserved. 76 ASIAN JOURNAL OF SURGERY VOL 26 NO 2 APRIL 2003

2 MIP IN AUSTRALIA invasive procedure in order to increase local referrals. Websites can still be accessed that claim unsubstantiated advantages of the minimally invasive approach and promote referral to the surgical centre concerned. 22 Against this background, endocrine surgeons in Australia agreed that MIP was a procedure that should only be introduced across the nation on the basis of evidence-based guidelines and protocols. MIP and ASERNIP-S Following the publication of a small case series describing the technique of endoscopic parathyroidectomy in the Australia and New Zealand Journal of Surgery in 1998, 23 endocrine surgeons in Australia agreed at their annual meeting in May 1998 that MIP should be introduced into Australia under the auspices of the Australian Safety and Efficacy Register of New Interventional Procedures Surgical (ASERNIP-S). This organization is a federally funded body working through the Royal Australasian College of Surgeons. The process for introducing new surgical procedures involves the following steps: systematic review, recommendation on the appropriateness or otherwise of the procedure, feasibility or controlled clinical trials, and finally, reassessment of the procedure in the light of any new information. 24 A systematic review was completed and co-published in the Australia and New Zealand Journal of Surgery and Archives of Surgery in April ,26 The authors reported that there were insufficient data in relation to the safety and efficacy of MIP, and that no firmly established method had been accepted as the standard technique. They recommended that ongoing monitoring and further controlled studies were required to ensure that MIP reached the high degree of satisfaction noted with open parathyroidectomy. On the basis of that report, ASERNIP-S then recommended that MIP be classified as a level 2.2 procedure, i.e. that the safety and/or efficacy of the procedure cannot be determined due to an incomplete and/or poor evidence base. A controlled clinical trial is required. Various endocrine surgical units around Australia submitted proposals to undertake feasibility studies of MIP using a variety of techniques including endoscopic parathyroidectomy, video- or endoscopic-assisted parathyroidectomy, minimal incision parathyroidectomy with IO-QPTH measurement, and radio-guided parathyroidectomy. We at Royal North Shore Hospital (RNS) initially undertook a feasibility study of endoscopic-assisted MIP under the auspices of ASERNIP-S. Endoscopic-assisted MIP at RNS A technique of endoscopic-assisted MIP was developed that was an adaptation of the previous reports of Miccoli et al, 17 Yeung and Ng 23 and others. The technique employed a 2.5-cm central suprasternal incision, with creation of a space by finger dissection and the use of an external lift-device. 27 A separate stab incision was made posterior to the sternomastoid muscle and a 4.4-mm telescope was inserted to visualize the space. The adenoma was dissected and removed through the suprasternal incision. In an initial report of 100 consecutive parathyroid procedures, 24 were performed endoscopically. The outcomes of the endoscopic-assisted technique were not statistically different from the open parathyroidectomies, with only one case of persistent hyperparathyroidism that was cured by subsequent open surgery. Two patients had temporary recurrent nerve neuropraxia, which resolved within several weeks of surgery. 27 At this stage, a second feasibility study of the minimal incision technique using the focused lateral approach was started. Altogether, a total of 49 endoscopicassisted parathyroidectomies were performed at RNS before changing over completely to the focused lateral approach. One reason for changing was that, frequently during the finger dissection necessary to create the working space for the telescope, the parathyroid adenoma would be encountered. It was soon apparent that it would be much easier and quicker to simply remove it under direct vision rather than continuing with a formal endoscopic-assisted dissection and removal. Focused, lateral, minimal incision parathyroidectomy at RNS A technique of MIP using the lateral focused approach was developed. 18 The principle of this technique is that a very small incision is made directly over the site of a previously localized parathyroid adenoma, which is then removed under direct vision (Figure 1). The procedure is offered with either local anaesthesia, or local anaesthetic infiltration supplemented by a laryngeal mask, with 96% of patients choosing the latter option. The lateral approach provides more direct access to parathyroid-bearing areas than does a central incision, and also appears to result in better cosmesis. The technique involves a 2-cm incision placed lateral to the medial margin of the sternomastoid muscle, and in a position, depending upon localization, to a superior or inferior gland. A working space is developed with finger dissection, the sternomastoid is retracted laterally, and dissection is continued lateral to the strap muscles 77 ASIAN JOURNAL OF SURGERY VOL 26 NO 2 APRIL

3 DELBRIDGE A B C Figure 1. Schematic diagrams showing focused, lateral, minimal incision parathyroidectomy techniques: A) siting of incisions for superior (a) and inferior (b) adenomas; B) dissection for an inferior adenoma at the lower pole of the thyroid and C) dissection for a superior adenoma in the tracheo-oesophageal groove. Reproduced here with permission from the publisher of Aust N Z J Surg (2002;72:147 51). and lateral to the thyroid fascia, down to the prevertebral fascia. After division of the middle thyroid vein, a superior parathyroid adenoma will commonly be found in the tracheooesophageal groove, whilst an inferior gland is found in the thyrothymic area, inferior to the lower pole of the thyroid. A prospective, randomized controlled study comparing open parathyroidectomy with focused lateral MIP was undertaken prior to changing completely to the latter technique. Thirty consecutive patients (15 in each group) presenting for parathyroidectomy and fitting the selection criteria for a minimally invasive approach were included after obtaining informed consent. Outcome measures included cure rate (serum calcium at 6 mo), operative time, postoperative complications and length of stay. There was no significant difference between the two groups with respect to cure rate, with 100% cured in both groups. There was no significant difference in postoperative complications, with one case of temporary neurapraxia in the lateral focused group that resolved after 6 weeks. The length of stay was the same in both groups (whole group mean ± SD, 1.2 ± 0.51 days), with the only difference being in the operative time (endoscopicassisted, 75 ± 12.3 min; lateral focused, 44 ± 8.4 min [p < 0.05]). It must be noted that this is the entire time in the operating room; actual surgical times were, of course, much shorter, with the fastest surgical time for a lateral focused approach being only 12 minutes. Initial experience with the technique was promising. In a report of the first 100 consecutive cases, there were three negative neck explorations and a conversion rate to open parathyroidectomy of 7%, with minimal morbidity. 28 From May 1999 to October 2002, 357 MIPs were performed at RNS. Cure rate was high at 98.5%, with six failed explorations, all cured at subsequent open surgery. In five of these cases, the failure was due to incorrect imaging, whilst in one case, it was due to the presence of parathyroid hyperplasia. There were three cases of permanent recurrent laryngeal nerve palsy (0.8%), and one bleed requiring re-operation. The key to such success is appropriate selection of cases. Patients considered suitable for MIP using this approach are patients where localization studies (sestamibi nuclear scan and ultrasound) are concordant and confirm the presence of a single parathyroid adenoma (about 43% of all patients presenting for surgery). Excluded are patients with any of the following: previous neck surgery or irradiation, presence of a large multinodular goitre (minimal multinodular change is not an exclusion criterion), possibility of hyperplasia (e.g. multiple endocrine neoplasia syndrome or secondary 78 ASIAN JOURNAL OF SURGERY VOL 26 NO 2 APRIL 2003

4 MIP IN AUSTRALIA hyperparathyroidism) and failure to localize to a single site. All such patients are offered a standard, open, four-gland parathyroidectomy. Assessment of completeness of parathyroid resection A number of techniques have been described to assess completeness of resection of abnormal parathyroid tissue, including IO-QPTH, 19 nuclear probe 20 and visualization of a normal ipsilateral parathyroid gland. 29 Despite earlier enthusiasm, interest in the use of the nuclear probe has waned due to concerns about its reliability and accuracy. 30 IO-QPTH remains the most popular technique, being used by 68% of surgeons according to an international survey. 1 Our own experience with IO-QPTH has shown that, although it is a very accurate technique, it often fails in the presence of double adenomas. 31 In other words, it is a very good technique when you do not need it, as the patient will have been cured anyway by removal of a single adenoma in 97% of cases. However, it is less useful in the presence of multigland pathology. Furthermore, there is a significant false-positive rate (6%), such that if the standard criteria are used, a number of patients will undergo an unnecessary conversion to an open procedure. As such, the technique, whilst accurate, cannot really be regarded as cost-effective. 32 We use the technique of simply determining PTH levels preoperatively and 30 minutes postoperatively, as measured on a routine laboratory run. This is less expensive and as accurate as IO-QPTH. Furthermore, it still allows for sameday patient discharge for the 97% of patients who will have Number of procedures Year Figure 2. Referrals to the University of Sydney Endocrine Surgical Unit for parathyroidectomy ( ). Reproduced here with permission from the publisher of Med J Aust (2002;177:246 9). been cured anyway by removal of a single adenoma. False positives with unnecessary conversion can be avoided by repeating the PTH and calcium levels later that evening for patients whose 30-minute PTH was elevated. The very small percentage (< 2%) of patients with a true failed operation can undergo open surgery during the same hospital admission, usually the next morning. Trends in parathyroid surgery Of interest is the effect that the introduction of MIP has had upon referrals for parathyroid surgery. In the past few years, referrals for parathyroid surgery to RNS have increased exponentially (Figure 2). 2 Whilst there are a number of factors that may well have contributed to such a dramatic increase, one factor is clearly the availability of MIP and the perception by referring endocrinologists that there is now a procedure that is simpler, easier and can be performed on a 1-hospitalday only basis, with safety and efficacy equal to the standard, four-gland, open exploration operation. A similar pattern of increasing referrals for parathyroid surgery seems to be occurring worldwide. In a recent previous study, we demonstrated that there has been an increase in parathyroid surgery worldwide, 1 a pattern that other individuals have also reported. 33 At the time of our survey (May 2000), the majority (56%) of endocrine surgeons worldwide were offering MIP and were performing it, on average, in 49% of cases. Of further interest was that the focused minimal incision approach had become the standard technique used, being employed by 92% of those responding to the international survey. Many surgeons reported starting endoscopic or video-assisted parathyroid surgery and then moving to the focused minimal incision technique because it was quicker, easier and produced equivalent cosmetic results and clinical outcomes. It was interesting to read a comment by Ng, the author of the very article that initially galvanized Australian endocrine surgeons to undertake a formal approach to the introduction of MIP, in a recent issue of the Australia and New Zealand Journal of Surgery. 34 He wrote, Very quickly I realized, as did Australian endocrine surgeons, that a parathyroid adenoma could be expeditiously removed under direct vision through a 2-cm incision directly over the preoperatively localized site without the utilization of unnecessarily complex endoscopic or endoscopic-assisted techniques. Similarly, Ikeda and Takami, in a recent monograph on minimally invasive endocrine surgery, commented that endoscopic and video-assisted 79 ASIAN JOURNAL OF SURGERY VOL 26 NO 2 APRIL

5 DELBRIDGE techniques reduce the level of invasiveness...however, these procedures are time-consuming and their complexity renders them difficult to reproduce in all surgical backgrounds...the mini-incision approach...simplifies the procedure, enabling the latter to be less technically demanding and time consuming while improving cosmesis. 35 It appears that the initial enthusiasm for technologically driven, endoscopic procedures has abated (at least in Australia and some parts of Asia), and that the focused, or mini-incision approach is now an accepted standard of care. Regardless of what technique is used, the introduction of MIP has challenged the role of the gold standard of conventional open parathyroidectomy, and has led to increasing referrals for parathyroid surgery. 33 Conclusion MIP was introduced into Australia only following an evidencebased review, and in the context of feasibility studies conducted under the auspices of ASERNIP-S, a federally funded body operating through the Royal Australasian College of Surgeons, which monitors the introduction of new surgical procedures. The lateral, focused, minimal incision technique has become the surgical approach favoured by most surgeons, and provides, in appropriately selected cases, a cure rate of 98%, with minimal morbidity. The introduction of MIP has resulted in a significant rise in referrals for parathyroid surgery. References 1. Sackett WR, Barraclough B, Reeve TS, Delbridge LW. 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