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Minimally invasive thyroid surgery
Best Practice & Research Clinical Endocrinology and Metabolism Vol. 15, No. 2, pp. 123±137, 2001
doi:10.1053/beem.2001.0130, available online at http://www.idealibrary.com on
1 Minimally invasive thyroid surgery Kazuo Shimizu
MD, FACS
Professor of the Department of Surgery Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo 113-8603, Japan
Endoscopic surgery is often considered to be `minimally invasive surgery' in the light of recent technical developments. Endoscopic neck surgery, including thyroid and parathyroid surgery, has developed rapidly over the past 2 years. The various techniques of thyroid surgery, including sites of incision and procedures for creating adequate working space, are described here. The cosmetic bene®ts of endoscopic versus conventional open surgery were evaluated by questionnaires sent to two groups of patients. The lower invasiveness of endoscopic surgery in terms of operating time and amount of bleeding is also discussed. Endoscopic surgery with a new, totally gasless anterior neck skin lifting method, with which we have now had much experience, will be described and its advantages discussed. Key words: minimally invasive surgery; thyroid tumour; video-assisted surgery; endoscopic surgery.
Minimally invasive surgery may be of bene®t because it reduces the level of physical invasiveness and the length of hospital stay, and because it results in a better cosmetic appearance. To satisfy this reduced invasiveness and cosmetic bene®t, endoscopic surgical techniques are rapidly being applied to virtually every surgical procedure. Endoscopic surgery has a smaller wound size and enables the positions of the wounds to be moved to places of cosmetic bene®t. This technique may also reduce the amount of bleeding and post-operative pain. In thyroid surgery, it obviates the need for a neck scar. An over-zealous pursuit of these objectives must not, however, allow the intrinsic surgical treatment to be compromised. In this chapter, the application of endoscopic surgery to endocrine neck surgery for thyroid lesions is described. The report of Gagner et al1 describing endoscopic subtotal parathyroidectomy for secondary hyperparathyroidism in 1996 represented the ®rst application of this technique to the ®eld of endocrine neck surgery. Since then, many experimental and clinical reports have appeared.2±10 There have been relatively few reports on endoscopic techniques for thyroid tumours because the gland is highly vascular and surrounded by critical nerves and blood vessels. Special care is required to create a working space in the narrow area of the anterior neck region. A variety of ingenious contrivances have been devised to address the challenges associated with this organ. We have been using an anterior neck skin lifting method (video-assisted neck surgery or VANS method)11±13 originally developed for the endoscopic surgery of thyroid tumours. Our ®rst patient was treated by this technique in March 1998,11 and we have subsequently applied it to over 120 patients. In this chapter, our technique and results in the context of the current state of minimally invasive thyroid surgery will be described, 1521±690X/01/02012315 $35.00/00
c 2001 Harcourt Publishers Ltd. *
124 K. Shimizu
principally covering the bene®ts and pitfalls of endoscopic thyroid surgery and the outlook for its future development. DEVELOPMENT AND CURRENT STATE OF ENDOSCOPIC THYROID SURGERY Conventional operative scars in the anterior region of the neck are nearly always exposed and therefore visible to others. Minimally invasive surgery places an emphasis on cosmetic bene®ts. This criterion was satis®ed in a report by Park14 in which a direct approach was made to the thyroid through a succession of neck wounds without a skin ¯ap. Lorenz et al15 described a small incision method for primary parathyroid tumours. Soon after Gagner's original description,1 endoscopic surgery for thyroid tumours was described in brief reports on thyroid lobectomy by Yeung et al16 and Huscher et al17 in 1997. Additional reports of endoscopic thyroid surgery11,12,18 and animal experimental studies19,20 from various institutes then appeared. LOCALIZING INCISIONS AND THE CREATION OF A WORKING SPACE Position of incisions Most endoscopic thyroid surgery involves between one and four transverse incisions with a main wound approximately 1 cm above the suprasternal notch, as described for endoscopic parathyroid surgery. The main wound is a 2 cm horizontal incision of the skin in the mid-line of the anterior neck, with lateral incisions for graspers and the endoscope. With a trocar sheath installed, the operation manipulation equipment is inserted via these wounds. Bellantone et al21 have described a totally gasless videoassisted thyroid lobectomy with only one 20 mm horizontal skin incision at 1 cm above the sternal notch. The working space was obtained using three retractors. Park14 also used one minimal incision in the neck, close to the position of the tumour (Figure 1A). Yeung et al16 and Huscher et al17 made a main incision just above the suprasternal notch and 2±3 other small incisions as additional potential port sites for graspers and the endoscope at the anterior margin of the sternomastoid muscle (Figure 1B). The mid-line wound sometimes stands out and tends to develop into a keloid scar. One report22 describes a surgical technique that uses a video-assisted lateral approach in which just one small main incision is made at the anterior border of the sternocleidomastoid muscle, where the operative scars are less conspicuous. More distantly placed incisions can be used, which can be divided into three types: a mammary areolar incision (Figure 2),23 an axillary incision (Figure 3)24 and an incision through the anterior chest wall under the clavicle (the VANS method) (Figure 4).11±13 The cosmetic results of each procedure are extremely satisfactory. Working space One of the most important issues in endoscopic surgery is the criterion of a large enough operative space and a clear visual ®eld. Endoscopic surgery of the neck requires that a wide working space be newly created where there is no pre-existing cavity. Two methods for providing such a working space have been devised; the carbon dioxide insuation method and the gasless anterior neck skin lifting method.
Minimally invasive thyroid surgery 125
A
(b) (a)
B
()
Figure 1. The position of the incisions. (A) One 2 cm incision is made 1 cm above the sternal notch (a) or close to the position of the tumour (b). (B) The main transverse incision is made at the suprasternal notch, and other incisions at the anterior margin of the sternomastoid muscle.
Carbon dioxide insuation The carbon dioxide insuation method creates operating space by insuating a closed area with carbon dioxide after incising the skin and the lower layer of the platysma. This method is used in the majority of endoscopic thyroid and parathyroid operations and involves the initial application of carbon dioxide at a pressure of approximately
126 K. Shimizu
Figure 2. Incisions along the mammary areola and at the parasternal site approaching the thyroid, indicated by dotted lines (Ohgami et al23). The working space is created by carbon dioxide insuation.
15±20 mmHg. This may cause complications such as severe subcutaneous emphysema, supraventricular tachycardia and hypercarbia.1,5,25 These problems can be alleviated by lowering the carbon dioxide pressure to 4,24 6,23,26 6±86 or 1018 mmHg. Ochiai et al26 performed a detailed study on the safety of this method and used indirect calorimetry to estimate the carbon dioxide absorption from the surgical ®eld during the operation with optimal carbon dioxide pressure adjusted to 6 mmHg. The hypercarbia was then eliminated. Anterior neck skin lifting method We developed the anterior neck skin lifting method based on the abdominal lift method created by Nagai et al.27 The lower layer of the platysma is dissected after the skin incision has been made, the working space is created by pulling the skin away from the body and upwards, opening up the wound (Figure 5). We have used this technique in more than 120 patients requiring thyroid and parathyroid surgery. Another recent consecutive study of 137 patients undergoing video-assisted endoscopic parathyroid surgery has been reported by Miccolli et al.28 In the following section, we describe the method, the improvements emanating from experience, and issues that require special attention when applying this technique.
Minimally invasive thyroid surgery 127
Figure 3. Incisions at the axillary area (Ikeda et al24). Three trocars and operative equipment are inserted through the wounds. The working space is obtained by carbon dioxide insuation.
Endoscopic thyroid surgery using the anterior neck skin lifting (VANS) method Objectives. Table 1 indicates a breakdown of the 110 patients in whom the VANS method was used. Indications for the technique were based on careful selection according to the following criteria: 1. a solitary follicular neoplasm; 2. no previous history of neck surgery;
128 K. Shimizu
(b)
(a) Figure 4. Incisions in the chest wall and the lateral neck. A main oblique incision (a) in the chest wall below the clavicle results in a scar that is concealed by open-necked clothing. Another 5 mm transverse incision (b) for the insertion of a 5 mm endoscope is made at the lateral neck. The working space is created by lifting Kirschner wires. Table 1. One hundred and ten patients with thyroid tumours treated using the VANS method. Female/male Ages Benign tumour Malignant tumour
106/4 16±74 (mean 41.8) 105 cases 5 cases
3. an adenoma suggested by pre-operative ®ne needle aspiration (FNA) biopsy and radiological and physiological examinations; 4. cytologically diagnosed papillary carcinoma measuring less than 1 cm in diameter with no lymph node involvement on computed tomography, ultrasonography and careful palpation; 5. no history of malignancy and/or the co-existence of another malignancy; 6. no haemorrhagic tendency. Operative equipment. One of the most important issues in performing endoscopic surgery is to obtain and maintain a clear and dry operating ®eld by careful haemostasis. After obtaining a working space by lifting the anterior neck skin, we use an ultrasonically activated scalpel (Harmonic Scalpel; Johnson & Johnson, Cincinnati, Ohio, USA) throughout the operation. The harmonic scalpel was initially applied by Amaral et al,29 ®rst experimentally and then clinically. It has since gained wide
Minimally invasive thyroid surgery 129
(b)
(a)
Figure 5. Anterior neck skin lifting method. The edges of the chest wall wound (a) and the lateral neck wound (b) are pulled up by sutured threads to create a wider working space. The edges of wound (a) are covered by silicon material to protect against mechanical stimulation of the skin.
acceptance and is currently preferred by surgeons worldwide. The mechanism for creating haemostasis is to vibrate the blades at 55 000 Hz, which generates heat up to a temperature of about 808C, leading to the denaturation of tissue proteins. The blood vessels are eectively sealed without causing damage to the surrounding tissue. The lifting equipment (Mizuho Ika, Tokyo, Japan) incorporates: 1. two pieces of Kirschner wire 1.2 mm in diameter; 2. two lifting handles with a chain; 3. an L-shaped pole. Other equipment includes: 1. an endoscope (Olympus, Tokyo, Japan) 5 mm in diameter and 30 cm in length, with angles of 0 degrees and 30 degrees); 2. graspers (Karl-Storz, Tuttlingen, Germany) (Johnson & Johnson, Cincinnati, Ohio, USA) 3 and 5 mm in diameter, and 20 and 22 cm in length). Operative procedure. Under general anaesthesia, the patient is placed in the supine position with the anterior neck slightly hyperextended. A video monitor, anaesthetic equipment and anaesthesiologist are positioned around the head of the operating table. There are generally three doctors on the operating team. For haemostasis, 30±40 ml saline containing 0.6% adrenaline (epinephrine) are injected subcutaneously into the anterior neck area. An oblique main incision (a), depending on the tumour size, is made for insertion of the Harmonic Scalpel and graspers approximately 3 cm below the clavicle on the chest wall ipsilateral to the
130 K. Shimizu
tumour, where open-necked clothing will conceal the wound. The layer under the platysma of the anterior neck is fully dissected through wound (a). Two pieces of Kirschner wire are inserted transversely in the subcutaneous layer using Nagai's abdominal wall lift method.27 These wires are lifted by two handles connected and ®xed to an L-shaped pole to create a tent-like working space. Another incision (b), of 5 mm is then made on the lateral neck for the insertion of the endoscope. The edge of wound (a) is covered with silicon material to prevent injury from mechanical and heat stimulation. The edges of wounds (a) and (b) are sutured and pulled forward by suture thread to help the surgeon obtain a wider space. No trocar sheaths are used in these wounds (see Figure 5 above). The approach to the thyroid is almost the same as in conventional surgery. Brie¯y, a space between the sternohyoid muscle and the omohyoid muscle is created by dividing them, and the thyroid is then exposed by splitting the sternothyroid muscle. If the tumour is larger than this space, the ipsilateral sternohyoid muscle is incised horizontally to obtain more room. Operative procedure for benign thyroid tumours. In subtotal lobectomy, the operative procedure varies according to the tumour size and location. If the tumour is well encapsulated and other abnormal lesions are not seen during pre-operative radiological investigation and intra-operative ®nger palpation, a small amount of normal thyroid, including the upper pole and/or the area behind the tumour, is intentionally preserved to prevent damage to the external branch of the superior laryngeal nerve and the recurrent laryngeal nerve. In such a situation, these nerves are not exposed. The remnant of thyroid after the excision of the tumour is sutured and repaired if necessary as in conventional surgery. Alternatively, near-total or total lobectomy may be needed. If the tumour is so large that it occupies almost a whole lobe, or if pre-operative FNA indicates a follicular lesion or Hurthle cell neoplasm, full exposure of the recurrent nerve during the operation is mandatory. First, the lower pole of the thyroid is mobilized, the recurrent nerve being carefully exposed as far as Berry's ligament. The thyroid is then dissected out of the area from caudad to cephalad. Because there is usually some normal thyroid tissue at the superior pole, an eort is made to preserve a small amount here in order to prevent injury of the external branch of the superior laryngeal nerve. After almost complete mobilization of the hemi-lobe from the trachea, the isthmus is vertically dissected to complete a near-total lobectomy. For total lobectomy, the superior thyroid artery and vein and the inferior thyroid artery are ligated and cut at the main trunks. The middle and inferior thyroid veins are cut only with the Harmonic Scalpel. The totally mobilized hemi-lobe is vertically dissected at the isthmus in a manner identical to that used in near-total thyroidectomy (Figure 6). We do not usually use clips for haemostasis because they produce an artefact should post-operative computed tomography and magnetic resonance imaging examinations be needed and because they are sometimes palpable under the skin, making patients feel uncomfortable. Operative procedure for malignant tumours. Total lobectomy and lymph node clearance is the minimal treatment for papillary cancers whose tumour size measures less than 1 cm in diameter. To create a working space, the main incision (a) for the insertion of the Harmonic Scalpel and graspers is made in the same manner as for benign tumours. After wide dissection of the layer beneath the platysma, a 2±3 cm incision (wound b), (instead of the 0.5 cm incision used for benign tumours) is made on the lateral neck on
Minimally invasive thyroid surgery 131
Figure 6. The mobilized left lobe of the thyroid is ®nally dissected from Berry's ligament using an ultrasonically activated scalpel. The recurrent nerve is totally visualized and the parathyroid glands identi®ed. The total lobectomy is almost complete.
the side of the tumour. The Harmonic Scalpel, graspers and endoscope can be inserted through wound (b) if necessary, depending on the operative manipulation required. This lateral wound should be wide enough to permit the dissection of lymph nodes on the opposite side of the paratracheal and pre-tracheal areas, the ipsilateral side of the paratracheal area and the caudad lateral compartment on the side of the tumour. Following the total lobectomy, the lymph node clearance is ®rst carried out in the central zone from the pre-laryngeal, pre-tracheal and paratracheal areas. If necessary, dissection is advanced to the lateral zone from caudad to cephalad. Sharp dissection using a pair of ®ne scissors is always performed in the area close to the recurrent nerve to avoid damage from thermal stimulation by the Harmonic Scalpel. FUTURE PROSPECTS FOR MINIMALLY INVASIVE THYROID SURGERY The introduction of endoscopic thyroid surgery is clearly bene®cial for patients from the cosmetic point of view. In a questionnaire study, we asked, `How do you feel now about the operative scar?' The results of the questionnaire revealed that 100% of respondents were `Extremely satis®ed' or `Satis®ed'. A questionnaire was given to patients who had undergone conventional neck surgery before the VANS method became available, this including the question, `Would you have selected the VANS method if this procedure had been available?' Ninety per cent of the respondents said `Yes'. The results of both questionnaires are shown in Table 2. Placing too much emphasis on eorts to reduce invasiveness and improve cosmesis must not, however, compromise the ability to achieve the essential goal of surgery.
132 K. Shimizu Table 2. Patient questionnaires. The ®rst questionnaire, given to patients who underwent the VANS method (n 74) 1. Are you extremely satis®ed with your operative scars? Yes 66.2% 2. Are you satis®ed with your operative scars? Yes 33.8% 3. Are you dissatis®ed with your operative scars? Yes 0% The second questionnaire, given to patients who underwent conventional surgery before the VANS method was available (n 50) 1. How do you feel now about the operative scars? a) I feel extremely uncomfortable 40.0% b) I feel uncomfortable 46.0% c) I do not feel uncomfortable 14.0% 2. Would you have selected the VANS method if this procedure had been available when you underwent surgery? a) I would have selected the VANS method 90.0% b) I would still have selected conventional surgery 10.0% 3. If you were to undergo thyroid or parathyroid surgery given the information that the [high] expense for VANS method surgery cannot be covered by insurance at present, which operation would you have selected, the VANS method or the conventional one? a) I would have selected the VANS method even in this situation 84.0% b) I would still have selected conventional surgery 16.0% VANS video-assisted neck surgery.
Table 3. Pre-operative cytological classi®cation of 110 cases of thyroid tumours treated by the video-assisted neck surgery method. Cytological diagnosis Class 1: benign non-neoplastic lesions Class 2: benign non-neoplastic lesions Class 3: cellular follicular lesions, Hurthle cell neoplasm Class 4: suspicion of malignancy Class 5: malignancy
Number of cases 2 58 45 2 3
The procedure is time-consuming and requires wide dissection of the layer under the skin from the anterior chest wall, breast and axilla. Can this, however, be de®ned as `less invasive' surgery when compared with conventional surgery? An accurate assessment of tumour size and location by careful pre-operative examination is needed to judge whether or not endoscopic surgery is possible and indicated. With benign tumours, the maximum size resected in our series was 5.5 cm in diameter. It is also extremely important to make a cytological dierential diagnosis between benign and malignant tumours by pre-operative FNA biopsy. Endoscopic thyroid surgery is basically limited to benign tumours and small papillary carcinomas. All 110 patients with a thyroid tumour who were treated by the VANS method at our institute, including ®ve patients with malignancy, were subjected to pre-operative FNA (Table 3). It is well known that papillary carcinoma of the thyroid has a favourable prognosis, more than 90% of the patients surviving for at least 10 years.30,31 It is still controversial whether or not prophylactic lymph node clearance should be performed on these patients, especially when the papillary carcinoma has a diameter less than 1 cm and there is no lymph node swelling shown on pre-operative examination. Henry et al32 asserted that tumour excision alone is sucient treatment for this type of tumour, but Mann and Buhr33 concluded that a total lobectomy with lymph
Minimally invasive thyroid surgery 133
node clearance of the central zone is necessary and that the dissection of the lateral compartment should be performed only when metastatic lymph node swelling is palpable. Sugino et al34 and Noguchi and Murakami35 recommended prophylactic lymph node clearance extending to the lateral compartment to avoid re-operation and because of the high incidence of occult regional lymph node metastasis. We have applied the VANS method to ®ve patients in whom papillary carcinoma was diagnosed by pre-operative FNA cytology. Two of them had a papillary carcinoma with a diameter of 5 or 7 mm and underwent total lobectomy and central node dissection. The other three had a papillary carcinoma of 12, 10, and 9 mm diameter located within the hemi-lobe with no apparent regional lymph node swelling. These three patients underwent total lobectomy and prophylactic lymph node clearance extending to the lateral compartment in a modi®ed neck dissection. It is still uncertain whether endoscopic thyroid surgery should be classi®ed as minimally invasive surgery, especially considering that it is a time-consuming operation compared with conventional surgery. As shown in Figure 7, however, the operating time and amount of bleeding associated with endoscopic thyroid surgery can be reduced as surgeons gain experience. There may be a learning curve of about 30 patients.
Operating time (min)
200
A
150 100 50 0
Amount of bleeding (ml)
200
A
B
C
D
E
F
A
B
C
D
E
F
B
150
100
50
0 Figure 7. Improvement in operating time (A) and amount of bleeding (B) in 60 patients treated for benign thyroid tumour by a single surgeon. The patients were divided into six groups, A±F, each containing 10 patients, from the ®rst (A) to the most recent (F).
134 K. Shimizu
The maximum size of a benign thyroid tumour that could be resected by our method was 5.5 cm in diameter. A tumour larger than this occupies the whole working space, and the operating ®eld cannot be displayed on the monitor during surgery, increasing the chance of injury to the surrounding tissues. The carbon dioxide insuation method produces a wider working space, and tumours larger than 5.5 cm have been successfully resected using this method.23 Regarding the indication of endoscopic surgery for malignant tumours, we recommend that such surgery should be limited to tumours of less than 1 cm in diameter, especially papillary carcinoma without lymph node involvement. Our consecutive study of more than 110 procedures involved no patients with Graves' disease (see Table 4 below). Considering the diculty of accurately regulating the thyroid remnant, the complexity of control of thyroid function and the possibility of post-operative complications, it seems that endoscopic surgery for this disease is less appropriate. Both methods for creating a working space provide a sucient view of the operating ®eld, but when consideration is given to the complexity of the technical eorts required for carbon dioxide pressure adjustment, the need for more instruments and the possibility of complications from carbon dioxide insuation, the gasless skin lifting method is likely to gain greater use. The gasless lifting method from the anterior chest wall has further advantages. The main wound is made high enough that the surgeon can reach the thyroid, palpate the tumour and perform the operative manipulations as easily as in conventional surgery. The main scar can be covered with open-necked clothing and both wounds (a) and (b) become inconspicuous within several months, almost disappearing by 1 year (Figure 8). All patients who had received this procedure expressed satisfaction with the cosmetic results. A summary of the application of the VANS method for endocrine neck surgery is shown in Table 4. Endocrine neck surgery was performed on 339 patients between 1 March 1998 and 15 November 2000. Among them, 112 (35.3%) endocrine neck operations, including those for malignancy and parathyroid tumours, were performed using the VANS method. Benign thyroid tumours accounted for 163 of the 339 patients, the VANS method being used in 105 (64.4%) of these. In contrast, only 5.7% of the malignant tumours and 9.1% of those with primary hyperparathyroidism were treated using the VANS approach. Stated another way, 93.8% (105 out of 112 patients) of the Table 4. Percentage of patients undergoing endocrine neck surgery using the video-assisted neck surgery (VANS) method (1 March 1998±15 November 2000). Disease Thyroid Benign Malignant Graves disease Chronic thyroiditis Parathyroid Primary hyperparathyroidism Secondary hyperparathyroidism Others Total
Total number of cases
Number undergoing VANS Percentage
312 163 87 61 1
110 105 5 0 0
35.1 64.4 5.7 0 0
24 22 2
2 2 0
8.3 9.1 0
3
0
0
339
112
33.0
Minimally invasive thyroid surgery 135
Figure 8. A 24-year-old woman 1 year after undergoing a thyroid operation using the video-assisted neck surgery method. The chest wall wound (arrowed) is inconspicuous, and the lateral neck wound has almost completely disappeared.
endoscopic operations were for a benign thyroid tumour. Endoscopic surgery has become the standard operation for benign thyroid tumours at our institute. It is likely that minimally invasive endoscopic thyroid surgical procedures will be used more frequently to treat benign thyroid tumours. Endoscopic thyroid surgery is a desirable procedure for many patients who have the appropriate operative indications from a cosmetic as well as a therapeutic viewpoint. Besides the cosmetic bene®t, the number of patients who complain of post-operative pain or anterior neck discomfort, such as a feeling of constriction, is also lower with endoscopic surgery than with conventional surgery. Miccoli et al36 performed a comparative study of video-assisted parathyroidectomy versus conventional surgery. Video-assisted endoscopic surgery was signi®cantly superior to conventional surgery in terms of both of these factors and was associated with a shorter post-operative hospital stay and a shorter rehabilitation time. In conclusion, endoscopic thyroid surgery can be favourably and extensively applied if there is careful selection of patients and if surgeons are skilled in the techniques of endoscopic surgery and conventional endocrine neck surgery. SUMMARY Endoscopic thyroid surgery is a new medical technique that has been applied clinically over the past 2±3 years. The endoscopic technique has potential cosmetic bene®ts over the conventional operation, which causes conspicuous scars in an exposed area of the anterior neck. Various incision sites have been used, including the neck, chest wall, axilla and breast. After dissecting the layer under the platysma from the main wound, there are
136 K. Shimizu
Practice points . learn various sites of incision: small transverse incisions in the neck, oblique chest wall incisions below the clavicle and axillary incisions . learn how to create a working space by the carbon dioxide insuation method and the gasless skin lifting method . learn how to remove the tumour . learn the indications for endoscopic thyroid surgery . learn the advantages and disadvantages of endoscopic thyroid surgery . learn the characteristic points of endoscopic thyroid surgery . learn conventional thyroid and parathyroid surgery
Research agenda . . . .
experience in the conventional technique of thyroid surgery experience in endoscopic surgery development of the device in endoscopic technique development of the operative device for endoscopic thyroid surgery
two procedures for creating a working space: carbon dioxide insuation and the gasless neck skin lifting procedure. In 110 patients undergoing video-assisted endoscopic thyroid surgery using the neck skin lifting method, all patients expressed satisfaction in terms of cosmesis. Postoperative pain and discomfort, and the length of the post-operative hospital stay, are reduced. The amount of bleeding is lower than with conventional surgery, and, with practice, the operating time is close to that of conventional surgery. Endoscopic surgery is still, however, a time-consuming operation. The intrinsic surgical goal of the treatment should not be compromised in the pursuit of less-invasive surgery. Care must be taken to select appropriate patients carefully and to train surgeons to be suciently skilled in the techniques required.
REFERENCES * 1. Gagner M. Endoscopic subtotal parathyroidectomy in patients with primary hyperparathyroidism. British Journal of Surgery 1996; 83: 875. (correspondence). 2. Norman J, Micheal H & Albrink H. Minimally invasive videoscopic parathyroidectomy: a feasibility study in dogs and humans. Journal of Laparoendoscopic and Advanced Surgical Technique 1997; 7: 301±306. 3. Brunt LM, James DB, Wu JS et al. Experimental development of an endoscopic approach to neck exploration and parathyroidectomy. Surgery 1997; 122: 893±901. 4. Miccoli P, Pinchera A, Cecchini G et al. Minimally invasive, video-assisted parathyroid surgery for primary hyperparathyroidism. Journal of Endocrinology Investigation 1997; 20: 429±430. 5. Naitoh T, Gagner M, Garcia-Ruiz A & Heniford BT. Endoscopic endocrine surgery in the neck: an initial report of endoscopic subtotal parathyroidectomy. Surgical Endoscopy 1998; 12: 202±205. 6. Yeung GHC & Jacob WTNG. The technique of endoscopic exploration for parathyroid adenoma of the neck. Australian and New Zealand Journal of Surgery 1998; 68: 147±150. 7. Gauger PG, Reeve TS & Delbridge LW. Endoscopically assisted, minimally invasive parathyroidectomy. British Journal of Surgery 1999; 86: 1563±1566. 8. Dralle H, Lorenz K & Nguyen-Thanh P. Minimally invasive video-assisted parathyroidectomy ± selective approach to localized single gland adenoma. Langenbeck's Archives of Surgery 1999; 384: 556±562.
Minimally invasive thyroid surgery 137 9. Reeve TS, Babidge WJ, Parkyn RF et al. Minimally invasive surgery for primary hyperparathyroidism: systematic review. Archives of Surgery 2000; 135: 481±487. 10. Delbridge LW, Dolan SJ, Hop TT et al. Minimally invasive parathyroidectomy: 50 consecutive cases. Medical Journal of Australia 2000; 172: 418±422. *11. Shimizu K, Akira S & Tanaka S. Video-assisted neck surgery: endoscopic resection of benign thyroid tumor aiming at scarless surgery on the neck. Journal of Surgical Oncology 1998; 69: 178±180. 12. Shimizu K, Akira S, Kitamura Y et al. Video-assisted neck surgery (VANS): endoscopic resection of a large nodule extending to the upper mediastinum ± with the aiming of scarless neck surgery. Thyroidology, Clinical and Experimental 1998; 10: 241±244. *13. Shimizu K, Akira S, Jasmi AY et al. Video-assisted neck surgery: endoscopic resection of thyroid tumors with a very minimal neck wound. Journal of the American College of Surgeons 1999; 188: 697±703. 14. Park CS. Minimally invasive open thyroidectomy: the role in the surgical management of thyroid cancer. Proceedings on Head and Neck Cancer 2000; 265±271. 15. Lorenz K, Nguyen-Thanh P & Dralle H. Unilateral open and minimally invasive procedures for primary hyperparathyroidism: a review of selective approaches. Langenbeck's Archives of Surgery 2000; 385: 106±117. 16. Yeung HC, Ng WT & Kong CK. Endoscopic thyroid and parathyroid surgery. Surgical Endoscopy 1997; 11: 1135 (letter). *17. Huscher CS, Chiodini S, Napolitano C & Recher A. Endoscopic right thyroid lobectomy. Surgical Endoscopy 1997; 11: 877 (letter). *18. Yeung GHC. Endoscopic surgery of the neck. A new frontier. Surgical Laparoscopy and Endoscopy 1998; 8: 227±232. 19. Kanauchi H, Yamasaki K, Ogawa T & Mimura Y. Endoscopic thyroidectomy in a porcine. Endocrine Journal 1998; 45: 135±136 (letter). 20. Jones DB, Quasebarth MA & Brunt LM. Videoendoscopic thyroidectomy: experimental development of a new technique. Surgical Laparoscopy, Endoscopy and Percutaneous Techniques 1999; 9: 167±170. 21. Bellantone R, Lombardi CP, Raaelli M et al. Minimally invasive, totally gasless video-assisted thyroid lobectomy. American Journal of Surgery 1999; 177: 342±343. 22. Henry JF, Defechereux T, Gramatica L & de Boissenzon C. Minimally invasive videoscopic parathyroidectomy by lateral approach. Langenbeck's Archives of Surgery 1999; 384: 298±301. *23. Ohgami M, Ishii S, Arisawa Y et al. Scarless endoscopic thyroidectomy: breast approach for better cosmesis. Surgical Laparoscopy, Endoscopy and Percutaneous Techniques 2000; 10: 1±5. *24. Ikeda Y, Takami H, Sasaki Y et al. Endoscopic neck surgery by the axillary approach. Journal of the American College of Surgeons 2000; 191: 336±340. *25. Gottlieb A, Juraj S, Zheng X-M & Gagner M. Massive subcutaneous emphysema and severe hypercarbia in a patient during endoscopic transcervical parathyroidectomy using carbon dioxide insuation. Anesthesia and Analgesia 1997; 84: 1154±1156. 26. Ochiai R, Takeda J, Noguchi J et al. Subcutaneous dioxide insuation does not cause hypercarbia during endoscopic thyroidectomy. Anesthesia and Analgesia 2000; 90: 760±762. *27. Nagai H, Kondo Y, Yasuda T et al. An abdominal wall-lift method of laparoscopic cholecystectomy without peritoneal insuation. Surgical Laparoscopy and Endoscopy 1999; 3: 175±179. *28. Miccoli P, Berti P, Conte M et al. Minimally invasive video-assisted parathyroidectomy: lesson learned from 137 cases. Journal of the American College of Surgeons 2000; 191: 613±618. 29. Amaral JF. Laparoscopic cholecystectomy in 200 consecutive patients using an ultrasonically activated scalpel. Surgical Laparoscopy and Endoscopy 1995; 5: 255±262. 30. Sugitani I & Fujimoto Y. Symptomatic versus asymptomatic papillary thyroid micro-carcinoma: a retrospective analysis of surgical outcome and prognostic factors. Endocrine Journal 1999; 46: 209±216. 31. Steinmuller T, Klupp J, Rayes N et al. Prognostic factors in patients with dierentiated thyroid carcinoma. European Journal of Surgery 2000; 166: 29±33. 32. Henry JF, Gramatica L, Denizot A et al. Morbidity of prophylactic lymph node dissection in the central neck area in patients with papillary thyroid carcinoma. Langenbeck's Archives of Surgery 1998; 383: 167±169. 33. Mann B & Buhr HJ. Lymph node dissection in patients with dierentiated thyroid carcinoma ± who bene®ts? Langenbeck's Archives of Surgery 1998; 383: 355±358. 34. Sugino K, Ito K, Ozaki O et al. Papillary microcarcinoma of the thyroid. Journal of Endocrinology Investigation 1998; 21: 445±448. 35. Noguchi S & Murakami N. The value of lymph-node dissection in patients with dierentiated thyroid cancer. Surgical Clinics of North America 1987; 67: 251±261. 36. Miccoli P, Bendinelli C, Berti P et al. Video-assisted versus conventional parathyroidectomy in primary hyperparathyroidism: a prospective randomized study. Surgery 1999; 126: 1117±1122.
doi:10.1053/beem.2001.0130, available online at http://www.idealibrary.com on
1 Minimally invasive thyroid surgery Kazuo Shimizu
MD, FACS
Professor of the Department of Surgery Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo 113-8603, Japan
Endoscopic surgery is often considered to be `minimally invasive surgery' in the light of recent technical developments. Endoscopic neck surgery, including thyroid and parathyroid surgery, has developed rapidly over the past 2 years. The various techniques of thyroid surgery, including sites of incision and procedures for creating adequate working space, are described here. The cosmetic bene®ts of endoscopic versus conventional open surgery were evaluated by questionnaires sent to two groups of patients. The lower invasiveness of endoscopic surgery in terms of operating time and amount of bleeding is also discussed. Endoscopic surgery with a new, totally gasless anterior neck skin lifting method, with which we have now had much experience, will be described and its advantages discussed. Key words: minimally invasive surgery; thyroid tumour; video-assisted surgery; endoscopic surgery.
Minimally invasive surgery may be of bene®t because it reduces the level of physical invasiveness and the length of hospital stay, and because it results in a better cosmetic appearance. To satisfy this reduced invasiveness and cosmetic bene®t, endoscopic surgical techniques are rapidly being applied to virtually every surgical procedure. Endoscopic surgery has a smaller wound size and enables the positions of the wounds to be moved to places of cosmetic bene®t. This technique may also reduce the amount of bleeding and post-operative pain. In thyroid surgery, it obviates the need for a neck scar. An over-zealous pursuit of these objectives must not, however, allow the intrinsic surgical treatment to be compromised. In this chapter, the application of endoscopic surgery to endocrine neck surgery for thyroid lesions is described. The report of Gagner et al1 describing endoscopic subtotal parathyroidectomy for secondary hyperparathyroidism in 1996 represented the ®rst application of this technique to the ®eld of endocrine neck surgery. Since then, many experimental and clinical reports have appeared.2±10 There have been relatively few reports on endoscopic techniques for thyroid tumours because the gland is highly vascular and surrounded by critical nerves and blood vessels. Special care is required to create a working space in the narrow area of the anterior neck region. A variety of ingenious contrivances have been devised to address the challenges associated with this organ. We have been using an anterior neck skin lifting method (video-assisted neck surgery or VANS method)11±13 originally developed for the endoscopic surgery of thyroid tumours. Our ®rst patient was treated by this technique in March 1998,11 and we have subsequently applied it to over 120 patients. In this chapter, our technique and results in the context of the current state of minimally invasive thyroid surgery will be described, 1521±690X/01/02012315 $35.00/00
c 2001 Harcourt Publishers Ltd. *
124 K. Shimizu
principally covering the bene®ts and pitfalls of endoscopic thyroid surgery and the outlook for its future development. DEVELOPMENT AND CURRENT STATE OF ENDOSCOPIC THYROID SURGERY Conventional operative scars in the anterior region of the neck are nearly always exposed and therefore visible to others. Minimally invasive surgery places an emphasis on cosmetic bene®ts. This criterion was satis®ed in a report by Park14 in which a direct approach was made to the thyroid through a succession of neck wounds without a skin ¯ap. Lorenz et al15 described a small incision method for primary parathyroid tumours. Soon after Gagner's original description,1 endoscopic surgery for thyroid tumours was described in brief reports on thyroid lobectomy by Yeung et al16 and Huscher et al17 in 1997. Additional reports of endoscopic thyroid surgery11,12,18 and animal experimental studies19,20 from various institutes then appeared. LOCALIZING INCISIONS AND THE CREATION OF A WORKING SPACE Position of incisions Most endoscopic thyroid surgery involves between one and four transverse incisions with a main wound approximately 1 cm above the suprasternal notch, as described for endoscopic parathyroid surgery. The main wound is a 2 cm horizontal incision of the skin in the mid-line of the anterior neck, with lateral incisions for graspers and the endoscope. With a trocar sheath installed, the operation manipulation equipment is inserted via these wounds. Bellantone et al21 have described a totally gasless videoassisted thyroid lobectomy with only one 20 mm horizontal skin incision at 1 cm above the sternal notch. The working space was obtained using three retractors. Park14 also used one minimal incision in the neck, close to the position of the tumour (Figure 1A). Yeung et al16 and Huscher et al17 made a main incision just above the suprasternal notch and 2±3 other small incisions as additional potential port sites for graspers and the endoscope at the anterior margin of the sternomastoid muscle (Figure 1B). The mid-line wound sometimes stands out and tends to develop into a keloid scar. One report22 describes a surgical technique that uses a video-assisted lateral approach in which just one small main incision is made at the anterior border of the sternocleidomastoid muscle, where the operative scars are less conspicuous. More distantly placed incisions can be used, which can be divided into three types: a mammary areolar incision (Figure 2),23 an axillary incision (Figure 3)24 and an incision through the anterior chest wall under the clavicle (the VANS method) (Figure 4).11±13 The cosmetic results of each procedure are extremely satisfactory. Working space One of the most important issues in endoscopic surgery is the criterion of a large enough operative space and a clear visual ®eld. Endoscopic surgery of the neck requires that a wide working space be newly created where there is no pre-existing cavity. Two methods for providing such a working space have been devised; the carbon dioxide insuation method and the gasless anterior neck skin lifting method.
Minimally invasive thyroid surgery 125
A
(b) (a)
B
()
Figure 1. The position of the incisions. (A) One 2 cm incision is made 1 cm above the sternal notch (a) or close to the position of the tumour (b). (B) The main transverse incision is made at the suprasternal notch, and other incisions at the anterior margin of the sternomastoid muscle.
Carbon dioxide insuation The carbon dioxide insuation method creates operating space by insuating a closed area with carbon dioxide after incising the skin and the lower layer of the platysma. This method is used in the majority of endoscopic thyroid and parathyroid operations and involves the initial application of carbon dioxide at a pressure of approximately
126 K. Shimizu
Figure 2. Incisions along the mammary areola and at the parasternal site approaching the thyroid, indicated by dotted lines (Ohgami et al23). The working space is created by carbon dioxide insuation.
15±20 mmHg. This may cause complications such as severe subcutaneous emphysema, supraventricular tachycardia and hypercarbia.1,5,25 These problems can be alleviated by lowering the carbon dioxide pressure to 4,24 6,23,26 6±86 or 1018 mmHg. Ochiai et al26 performed a detailed study on the safety of this method and used indirect calorimetry to estimate the carbon dioxide absorption from the surgical ®eld during the operation with optimal carbon dioxide pressure adjusted to 6 mmHg. The hypercarbia was then eliminated. Anterior neck skin lifting method We developed the anterior neck skin lifting method based on the abdominal lift method created by Nagai et al.27 The lower layer of the platysma is dissected after the skin incision has been made, the working space is created by pulling the skin away from the body and upwards, opening up the wound (Figure 5). We have used this technique in more than 120 patients requiring thyroid and parathyroid surgery. Another recent consecutive study of 137 patients undergoing video-assisted endoscopic parathyroid surgery has been reported by Miccolli et al.28 In the following section, we describe the method, the improvements emanating from experience, and issues that require special attention when applying this technique.
Minimally invasive thyroid surgery 127
Figure 3. Incisions at the axillary area (Ikeda et al24). Three trocars and operative equipment are inserted through the wounds. The working space is obtained by carbon dioxide insuation.
Endoscopic thyroid surgery using the anterior neck skin lifting (VANS) method Objectives. Table 1 indicates a breakdown of the 110 patients in whom the VANS method was used. Indications for the technique were based on careful selection according to the following criteria: 1. a solitary follicular neoplasm; 2. no previous history of neck surgery;
128 K. Shimizu
(b)
(a) Figure 4. Incisions in the chest wall and the lateral neck. A main oblique incision (a) in the chest wall below the clavicle results in a scar that is concealed by open-necked clothing. Another 5 mm transverse incision (b) for the insertion of a 5 mm endoscope is made at the lateral neck. The working space is created by lifting Kirschner wires. Table 1. One hundred and ten patients with thyroid tumours treated using the VANS method. Female/male Ages Benign tumour Malignant tumour
106/4 16±74 (mean 41.8) 105 cases 5 cases
3. an adenoma suggested by pre-operative ®ne needle aspiration (FNA) biopsy and radiological and physiological examinations; 4. cytologically diagnosed papillary carcinoma measuring less than 1 cm in diameter with no lymph node involvement on computed tomography, ultrasonography and careful palpation; 5. no history of malignancy and/or the co-existence of another malignancy; 6. no haemorrhagic tendency. Operative equipment. One of the most important issues in performing endoscopic surgery is to obtain and maintain a clear and dry operating ®eld by careful haemostasis. After obtaining a working space by lifting the anterior neck skin, we use an ultrasonically activated scalpel (Harmonic Scalpel; Johnson & Johnson, Cincinnati, Ohio, USA) throughout the operation. The harmonic scalpel was initially applied by Amaral et al,29 ®rst experimentally and then clinically. It has since gained wide
Minimally invasive thyroid surgery 129
(b)
(a)
Figure 5. Anterior neck skin lifting method. The edges of the chest wall wound (a) and the lateral neck wound (b) are pulled up by sutured threads to create a wider working space. The edges of wound (a) are covered by silicon material to protect against mechanical stimulation of the skin.
acceptance and is currently preferred by surgeons worldwide. The mechanism for creating haemostasis is to vibrate the blades at 55 000 Hz, which generates heat up to a temperature of about 808C, leading to the denaturation of tissue proteins. The blood vessels are eectively sealed without causing damage to the surrounding tissue. The lifting equipment (Mizuho Ika, Tokyo, Japan) incorporates: 1. two pieces of Kirschner wire 1.2 mm in diameter; 2. two lifting handles with a chain; 3. an L-shaped pole. Other equipment includes: 1. an endoscope (Olympus, Tokyo, Japan) 5 mm in diameter and 30 cm in length, with angles of 0 degrees and 30 degrees); 2. graspers (Karl-Storz, Tuttlingen, Germany) (Johnson & Johnson, Cincinnati, Ohio, USA) 3 and 5 mm in diameter, and 20 and 22 cm in length). Operative procedure. Under general anaesthesia, the patient is placed in the supine position with the anterior neck slightly hyperextended. A video monitor, anaesthetic equipment and anaesthesiologist are positioned around the head of the operating table. There are generally three doctors on the operating team. For haemostasis, 30±40 ml saline containing 0.6% adrenaline (epinephrine) are injected subcutaneously into the anterior neck area. An oblique main incision (a), depending on the tumour size, is made for insertion of the Harmonic Scalpel and graspers approximately 3 cm below the clavicle on the chest wall ipsilateral to the
130 K. Shimizu
tumour, where open-necked clothing will conceal the wound. The layer under the platysma of the anterior neck is fully dissected through wound (a). Two pieces of Kirschner wire are inserted transversely in the subcutaneous layer using Nagai's abdominal wall lift method.27 These wires are lifted by two handles connected and ®xed to an L-shaped pole to create a tent-like working space. Another incision (b), of 5 mm is then made on the lateral neck for the insertion of the endoscope. The edge of wound (a) is covered with silicon material to prevent injury from mechanical and heat stimulation. The edges of wounds (a) and (b) are sutured and pulled forward by suture thread to help the surgeon obtain a wider space. No trocar sheaths are used in these wounds (see Figure 5 above). The approach to the thyroid is almost the same as in conventional surgery. Brie¯y, a space between the sternohyoid muscle and the omohyoid muscle is created by dividing them, and the thyroid is then exposed by splitting the sternothyroid muscle. If the tumour is larger than this space, the ipsilateral sternohyoid muscle is incised horizontally to obtain more room. Operative procedure for benign thyroid tumours. In subtotal lobectomy, the operative procedure varies according to the tumour size and location. If the tumour is well encapsulated and other abnormal lesions are not seen during pre-operative radiological investigation and intra-operative ®nger palpation, a small amount of normal thyroid, including the upper pole and/or the area behind the tumour, is intentionally preserved to prevent damage to the external branch of the superior laryngeal nerve and the recurrent laryngeal nerve. In such a situation, these nerves are not exposed. The remnant of thyroid after the excision of the tumour is sutured and repaired if necessary as in conventional surgery. Alternatively, near-total or total lobectomy may be needed. If the tumour is so large that it occupies almost a whole lobe, or if pre-operative FNA indicates a follicular lesion or Hurthle cell neoplasm, full exposure of the recurrent nerve during the operation is mandatory. First, the lower pole of the thyroid is mobilized, the recurrent nerve being carefully exposed as far as Berry's ligament. The thyroid is then dissected out of the area from caudad to cephalad. Because there is usually some normal thyroid tissue at the superior pole, an eort is made to preserve a small amount here in order to prevent injury of the external branch of the superior laryngeal nerve. After almost complete mobilization of the hemi-lobe from the trachea, the isthmus is vertically dissected to complete a near-total lobectomy. For total lobectomy, the superior thyroid artery and vein and the inferior thyroid artery are ligated and cut at the main trunks. The middle and inferior thyroid veins are cut only with the Harmonic Scalpel. The totally mobilized hemi-lobe is vertically dissected at the isthmus in a manner identical to that used in near-total thyroidectomy (Figure 6). We do not usually use clips for haemostasis because they produce an artefact should post-operative computed tomography and magnetic resonance imaging examinations be needed and because they are sometimes palpable under the skin, making patients feel uncomfortable. Operative procedure for malignant tumours. Total lobectomy and lymph node clearance is the minimal treatment for papillary cancers whose tumour size measures less than 1 cm in diameter. To create a working space, the main incision (a) for the insertion of the Harmonic Scalpel and graspers is made in the same manner as for benign tumours. After wide dissection of the layer beneath the platysma, a 2±3 cm incision (wound b), (instead of the 0.5 cm incision used for benign tumours) is made on the lateral neck on
Minimally invasive thyroid surgery 131
Figure 6. The mobilized left lobe of the thyroid is ®nally dissected from Berry's ligament using an ultrasonically activated scalpel. The recurrent nerve is totally visualized and the parathyroid glands identi®ed. The total lobectomy is almost complete.
the side of the tumour. The Harmonic Scalpel, graspers and endoscope can be inserted through wound (b) if necessary, depending on the operative manipulation required. This lateral wound should be wide enough to permit the dissection of lymph nodes on the opposite side of the paratracheal and pre-tracheal areas, the ipsilateral side of the paratracheal area and the caudad lateral compartment on the side of the tumour. Following the total lobectomy, the lymph node clearance is ®rst carried out in the central zone from the pre-laryngeal, pre-tracheal and paratracheal areas. If necessary, dissection is advanced to the lateral zone from caudad to cephalad. Sharp dissection using a pair of ®ne scissors is always performed in the area close to the recurrent nerve to avoid damage from thermal stimulation by the Harmonic Scalpel. FUTURE PROSPECTS FOR MINIMALLY INVASIVE THYROID SURGERY The introduction of endoscopic thyroid surgery is clearly bene®cial for patients from the cosmetic point of view. In a questionnaire study, we asked, `How do you feel now about the operative scar?' The results of the questionnaire revealed that 100% of respondents were `Extremely satis®ed' or `Satis®ed'. A questionnaire was given to patients who had undergone conventional neck surgery before the VANS method became available, this including the question, `Would you have selected the VANS method if this procedure had been available?' Ninety per cent of the respondents said `Yes'. The results of both questionnaires are shown in Table 2. Placing too much emphasis on eorts to reduce invasiveness and improve cosmesis must not, however, compromise the ability to achieve the essential goal of surgery.
132 K. Shimizu Table 2. Patient questionnaires. The ®rst questionnaire, given to patients who underwent the VANS method (n 74) 1. Are you extremely satis®ed with your operative scars? Yes 66.2% 2. Are you satis®ed with your operative scars? Yes 33.8% 3. Are you dissatis®ed with your operative scars? Yes 0% The second questionnaire, given to patients who underwent conventional surgery before the VANS method was available (n 50) 1. How do you feel now about the operative scars? a) I feel extremely uncomfortable 40.0% b) I feel uncomfortable 46.0% c) I do not feel uncomfortable 14.0% 2. Would you have selected the VANS method if this procedure had been available when you underwent surgery? a) I would have selected the VANS method 90.0% b) I would still have selected conventional surgery 10.0% 3. If you were to undergo thyroid or parathyroid surgery given the information that the [high] expense for VANS method surgery cannot be covered by insurance at present, which operation would you have selected, the VANS method or the conventional one? a) I would have selected the VANS method even in this situation 84.0% b) I would still have selected conventional surgery 16.0% VANS video-assisted neck surgery.
Table 3. Pre-operative cytological classi®cation of 110 cases of thyroid tumours treated by the video-assisted neck surgery method. Cytological diagnosis Class 1: benign non-neoplastic lesions Class 2: benign non-neoplastic lesions Class 3: cellular follicular lesions, Hurthle cell neoplasm Class 4: suspicion of malignancy Class 5: malignancy
Number of cases 2 58 45 2 3
The procedure is time-consuming and requires wide dissection of the layer under the skin from the anterior chest wall, breast and axilla. Can this, however, be de®ned as `less invasive' surgery when compared with conventional surgery? An accurate assessment of tumour size and location by careful pre-operative examination is needed to judge whether or not endoscopic surgery is possible and indicated. With benign tumours, the maximum size resected in our series was 5.5 cm in diameter. It is also extremely important to make a cytological dierential diagnosis between benign and malignant tumours by pre-operative FNA biopsy. Endoscopic thyroid surgery is basically limited to benign tumours and small papillary carcinomas. All 110 patients with a thyroid tumour who were treated by the VANS method at our institute, including ®ve patients with malignancy, were subjected to pre-operative FNA (Table 3). It is well known that papillary carcinoma of the thyroid has a favourable prognosis, more than 90% of the patients surviving for at least 10 years.30,31 It is still controversial whether or not prophylactic lymph node clearance should be performed on these patients, especially when the papillary carcinoma has a diameter less than 1 cm and there is no lymph node swelling shown on pre-operative examination. Henry et al32 asserted that tumour excision alone is sucient treatment for this type of tumour, but Mann and Buhr33 concluded that a total lobectomy with lymph
Minimally invasive thyroid surgery 133
node clearance of the central zone is necessary and that the dissection of the lateral compartment should be performed only when metastatic lymph node swelling is palpable. Sugino et al34 and Noguchi and Murakami35 recommended prophylactic lymph node clearance extending to the lateral compartment to avoid re-operation and because of the high incidence of occult regional lymph node metastasis. We have applied the VANS method to ®ve patients in whom papillary carcinoma was diagnosed by pre-operative FNA cytology. Two of them had a papillary carcinoma with a diameter of 5 or 7 mm and underwent total lobectomy and central node dissection. The other three had a papillary carcinoma of 12, 10, and 9 mm diameter located within the hemi-lobe with no apparent regional lymph node swelling. These three patients underwent total lobectomy and prophylactic lymph node clearance extending to the lateral compartment in a modi®ed neck dissection. It is still uncertain whether endoscopic thyroid surgery should be classi®ed as minimally invasive surgery, especially considering that it is a time-consuming operation compared with conventional surgery. As shown in Figure 7, however, the operating time and amount of bleeding associated with endoscopic thyroid surgery can be reduced as surgeons gain experience. There may be a learning curve of about 30 patients.
Operating time (min)
200
A
150 100 50 0
Amount of bleeding (ml)
200
A
B
C
D
E
F
A
B
C
D
E
F
B
150
100
50
0 Figure 7. Improvement in operating time (A) and amount of bleeding (B) in 60 patients treated for benign thyroid tumour by a single surgeon. The patients were divided into six groups, A±F, each containing 10 patients, from the ®rst (A) to the most recent (F).
134 K. Shimizu
The maximum size of a benign thyroid tumour that could be resected by our method was 5.5 cm in diameter. A tumour larger than this occupies the whole working space, and the operating ®eld cannot be displayed on the monitor during surgery, increasing the chance of injury to the surrounding tissues. The carbon dioxide insuation method produces a wider working space, and tumours larger than 5.5 cm have been successfully resected using this method.23 Regarding the indication of endoscopic surgery for malignant tumours, we recommend that such surgery should be limited to tumours of less than 1 cm in diameter, especially papillary carcinoma without lymph node involvement. Our consecutive study of more than 110 procedures involved no patients with Graves' disease (see Table 4 below). Considering the diculty of accurately regulating the thyroid remnant, the complexity of control of thyroid function and the possibility of post-operative complications, it seems that endoscopic surgery for this disease is less appropriate. Both methods for creating a working space provide a sucient view of the operating ®eld, but when consideration is given to the complexity of the technical eorts required for carbon dioxide pressure adjustment, the need for more instruments and the possibility of complications from carbon dioxide insuation, the gasless skin lifting method is likely to gain greater use. The gasless lifting method from the anterior chest wall has further advantages. The main wound is made high enough that the surgeon can reach the thyroid, palpate the tumour and perform the operative manipulations as easily as in conventional surgery. The main scar can be covered with open-necked clothing and both wounds (a) and (b) become inconspicuous within several months, almost disappearing by 1 year (Figure 8). All patients who had received this procedure expressed satisfaction with the cosmetic results. A summary of the application of the VANS method for endocrine neck surgery is shown in Table 4. Endocrine neck surgery was performed on 339 patients between 1 March 1998 and 15 November 2000. Among them, 112 (35.3%) endocrine neck operations, including those for malignancy and parathyroid tumours, were performed using the VANS method. Benign thyroid tumours accounted for 163 of the 339 patients, the VANS method being used in 105 (64.4%) of these. In contrast, only 5.7% of the malignant tumours and 9.1% of those with primary hyperparathyroidism were treated using the VANS approach. Stated another way, 93.8% (105 out of 112 patients) of the Table 4. Percentage of patients undergoing endocrine neck surgery using the video-assisted neck surgery (VANS) method (1 March 1998±15 November 2000). Disease Thyroid Benign Malignant Graves disease Chronic thyroiditis Parathyroid Primary hyperparathyroidism Secondary hyperparathyroidism Others Total
Total number of cases
Number undergoing VANS Percentage
312 163 87 61 1
110 105 5 0 0
35.1 64.4 5.7 0 0
24 22 2
2 2 0
8.3 9.1 0
3
0
0
339
112
33.0
Minimally invasive thyroid surgery 135
Figure 8. A 24-year-old woman 1 year after undergoing a thyroid operation using the video-assisted neck surgery method. The chest wall wound (arrowed) is inconspicuous, and the lateral neck wound has almost completely disappeared.
endoscopic operations were for a benign thyroid tumour. Endoscopic surgery has become the standard operation for benign thyroid tumours at our institute. It is likely that minimally invasive endoscopic thyroid surgical procedures will be used more frequently to treat benign thyroid tumours. Endoscopic thyroid surgery is a desirable procedure for many patients who have the appropriate operative indications from a cosmetic as well as a therapeutic viewpoint. Besides the cosmetic bene®t, the number of patients who complain of post-operative pain or anterior neck discomfort, such as a feeling of constriction, is also lower with endoscopic surgery than with conventional surgery. Miccoli et al36 performed a comparative study of video-assisted parathyroidectomy versus conventional surgery. Video-assisted endoscopic surgery was signi®cantly superior to conventional surgery in terms of both of these factors and was associated with a shorter post-operative hospital stay and a shorter rehabilitation time. In conclusion, endoscopic thyroid surgery can be favourably and extensively applied if there is careful selection of patients and if surgeons are skilled in the techniques of endoscopic surgery and conventional endocrine neck surgery. SUMMARY Endoscopic thyroid surgery is a new medical technique that has been applied clinically over the past 2±3 years. The endoscopic technique has potential cosmetic bene®ts over the conventional operation, which causes conspicuous scars in an exposed area of the anterior neck. Various incision sites have been used, including the neck, chest wall, axilla and breast. After dissecting the layer under the platysma from the main wound, there are
136 K. Shimizu
Practice points . learn various sites of incision: small transverse incisions in the neck, oblique chest wall incisions below the clavicle and axillary incisions . learn how to create a working space by the carbon dioxide insuation method and the gasless skin lifting method . learn how to remove the tumour . learn the indications for endoscopic thyroid surgery . learn the advantages and disadvantages of endoscopic thyroid surgery . learn the characteristic points of endoscopic thyroid surgery . learn conventional thyroid and parathyroid surgery
Research agenda . . . .
experience in the conventional technique of thyroid surgery experience in endoscopic surgery development of the device in endoscopic technique development of the operative device for endoscopic thyroid surgery
two procedures for creating a working space: carbon dioxide insuation and the gasless neck skin lifting procedure. In 110 patients undergoing video-assisted endoscopic thyroid surgery using the neck skin lifting method, all patients expressed satisfaction in terms of cosmesis. Postoperative pain and discomfort, and the length of the post-operative hospital stay, are reduced. The amount of bleeding is lower than with conventional surgery, and, with practice, the operating time is close to that of conventional surgery. Endoscopic surgery is still, however, a time-consuming operation. The intrinsic surgical goal of the treatment should not be compromised in the pursuit of less-invasive surgery. Care must be taken to select appropriate patients carefully and to train surgeons to be suciently skilled in the techniques required.
REFERENCES * 1. Gagner M. Endoscopic subtotal parathyroidectomy in patients with primary hyperparathyroidism. British Journal of Surgery 1996; 83: 875. (correspondence). 2. Norman J, Micheal H & Albrink H. Minimally invasive videoscopic parathyroidectomy: a feasibility study in dogs and humans. Journal of Laparoendoscopic and Advanced Surgical Technique 1997; 7: 301±306. 3. Brunt LM, James DB, Wu JS et al. Experimental development of an endoscopic approach to neck exploration and parathyroidectomy. Surgery 1997; 122: 893±901. 4. Miccoli P, Pinchera A, Cecchini G et al. Minimally invasive, video-assisted parathyroid surgery for primary hyperparathyroidism. Journal of Endocrinology Investigation 1997; 20: 429±430. 5. Naitoh T, Gagner M, Garcia-Ruiz A & Heniford BT. Endoscopic endocrine surgery in the neck: an initial report of endoscopic subtotal parathyroidectomy. Surgical Endoscopy 1998; 12: 202±205. 6. Yeung GHC & Jacob WTNG. The technique of endoscopic exploration for parathyroid adenoma of the neck. Australian and New Zealand Journal of Surgery 1998; 68: 147±150. 7. Gauger PG, Reeve TS & Delbridge LW. Endoscopically assisted, minimally invasive parathyroidectomy. British Journal of Surgery 1999; 86: 1563±1566. 8. Dralle H, Lorenz K & Nguyen-Thanh P. Minimally invasive video-assisted parathyroidectomy ± selective approach to localized single gland adenoma. Langenbeck's Archives of Surgery 1999; 384: 556±562.
Minimally invasive thyroid surgery 137 9. Reeve TS, Babidge WJ, Parkyn RF et al. Minimally invasive surgery for primary hyperparathyroidism: systematic review. Archives of Surgery 2000; 135: 481±487. 10. Delbridge LW, Dolan SJ, Hop TT et al. Minimally invasive parathyroidectomy: 50 consecutive cases. Medical Journal of Australia 2000; 172: 418±422. *11. Shimizu K, Akira S & Tanaka S. Video-assisted neck surgery: endoscopic resection of benign thyroid tumor aiming at scarless surgery on the neck. Journal of Surgical Oncology 1998; 69: 178±180. 12. Shimizu K, Akira S, Kitamura Y et al. Video-assisted neck surgery (VANS): endoscopic resection of a large nodule extending to the upper mediastinum ± with the aiming of scarless neck surgery. Thyroidology, Clinical and Experimental 1998; 10: 241±244. *13. Shimizu K, Akira S, Jasmi AY et al. Video-assisted neck surgery: endoscopic resection of thyroid tumors with a very minimal neck wound. Journal of the American College of Surgeons 1999; 188: 697±703. 14. Park CS. Minimally invasive open thyroidectomy: the role in the surgical management of thyroid cancer. Proceedings on Head and Neck Cancer 2000; 265±271. 15. Lorenz K, Nguyen-Thanh P & Dralle H. Unilateral open and minimally invasive procedures for primary hyperparathyroidism: a review of selective approaches. Langenbeck's Archives of Surgery 2000; 385: 106±117. 16. Yeung HC, Ng WT & Kong CK. Endoscopic thyroid and parathyroid surgery. Surgical Endoscopy 1997; 11: 1135 (letter). *17. Huscher CS, Chiodini S, Napolitano C & Recher A. Endoscopic right thyroid lobectomy. Surgical Endoscopy 1997; 11: 877 (letter). *18. Yeung GHC. Endoscopic surgery of the neck. A new frontier. Surgical Laparoscopy and Endoscopy 1998; 8: 227±232. 19. Kanauchi H, Yamasaki K, Ogawa T & Mimura Y. Endoscopic thyroidectomy in a porcine. Endocrine Journal 1998; 45: 135±136 (letter). 20. Jones DB, Quasebarth MA & Brunt LM. Videoendoscopic thyroidectomy: experimental development of a new technique. Surgical Laparoscopy, Endoscopy and Percutaneous Techniques 1999; 9: 167±170. 21. Bellantone R, Lombardi CP, Raaelli M et al. Minimally invasive, totally gasless video-assisted thyroid lobectomy. American Journal of Surgery 1999; 177: 342±343. 22. Henry JF, Defechereux T, Gramatica L & de Boissenzon C. Minimally invasive videoscopic parathyroidectomy by lateral approach. Langenbeck's Archives of Surgery 1999; 384: 298±301. *23. Ohgami M, Ishii S, Arisawa Y et al. Scarless endoscopic thyroidectomy: breast approach for better cosmesis. Surgical Laparoscopy, Endoscopy and Percutaneous Techniques 2000; 10: 1±5. *24. Ikeda Y, Takami H, Sasaki Y et al. Endoscopic neck surgery by the axillary approach. Journal of the American College of Surgeons 2000; 191: 336±340. *25. Gottlieb A, Juraj S, Zheng X-M & Gagner M. Massive subcutaneous emphysema and severe hypercarbia in a patient during endoscopic transcervical parathyroidectomy using carbon dioxide insuation. Anesthesia and Analgesia 1997; 84: 1154±1156. 26. Ochiai R, Takeda J, Noguchi J et al. Subcutaneous dioxide insuation does not cause hypercarbia during endoscopic thyroidectomy. Anesthesia and Analgesia 2000; 90: 760±762. *27. Nagai H, Kondo Y, Yasuda T et al. An abdominal wall-lift method of laparoscopic cholecystectomy without peritoneal insuation. Surgical Laparoscopy and Endoscopy 1999; 3: 175±179. *28. Miccoli P, Berti P, Conte M et al. Minimally invasive video-assisted parathyroidectomy: lesson learned from 137 cases. Journal of the American College of Surgeons 2000; 191: 613±618. 29. Amaral JF. Laparoscopic cholecystectomy in 200 consecutive patients using an ultrasonically activated scalpel. Surgical Laparoscopy and Endoscopy 1995; 5: 255±262. 30. Sugitani I & Fujimoto Y. Symptomatic versus asymptomatic papillary thyroid micro-carcinoma: a retrospective analysis of surgical outcome and prognostic factors. Endocrine Journal 1999; 46: 209±216. 31. Steinmuller T, Klupp J, Rayes N et al. Prognostic factors in patients with dierentiated thyroid carcinoma. European Journal of Surgery 2000; 166: 29±33. 32. Henry JF, Gramatica L, Denizot A et al. Morbidity of prophylactic lymph node dissection in the central neck area in patients with papillary thyroid carcinoma. Langenbeck's Archives of Surgery 1998; 383: 167±169. 33. Mann B & Buhr HJ. Lymph node dissection in patients with dierentiated thyroid carcinoma ± who bene®ts? Langenbeck's Archives of Surgery 1998; 383: 355±358. 34. Sugino K, Ito K, Ozaki O et al. Papillary microcarcinoma of the thyroid. Journal of Endocrinology Investigation 1998; 21: 445±448. 35. Noguchi S & Murakami N. The value of lymph-node dissection in patients with dierentiated thyroid cancer. Surgical Clinics of North America 1987; 67: 251±261. 36. Miccoli P, Bendinelli C, Berti P et al. Video-assisted versus conventional parathyroidectomy in primary hyperparathyroidism: a prospective randomized study. Surgery 1999; 126: 1117±1122.