JOURNAL OF LAPAROENDOSCOPIC & ADVANCED SURGICAL TECHNIQUES Volume 23, Number 12, 2013 ª Mary Ann Liebert, Inc. DOI: 10.1089/lap.2013.0186
A Novel Method for Creating Working Space During Endoscopic Thyroidectomy via Bilateral Areolar Approach Yi-Hong Tan, MS,1 Guo-Neng Du, MS,1 Yu-Gen Xiao, MS,1 Wan-Shou Qiu, MS,2 and Tao Wu, MS 3
Abstract
Background: Endoscopic thyroidectomy (ET) can be performed through the bilateral areolar approach (BAA). A working space (WS) is typically created on the surface of the pectoral fascia in the chest wall and in the subplatysmal space in the neck. There are several limitations of using this WS. The aim of this study was to establish a new WS for ET. Subjects and Methods: A retrospective review was performed on 85 patients with benign thyroid nodules who had undergone ET through a BAA. A WS was created between the anterior and poster layers of the superficial pectoral fascia (SPF) in the chest and underneath the deep layer of the investing layer (IL) in the neck. Results: The time for creating the WS was 7.2 – 2.1 (range, 5–12) minutes. No hemorrhage occurred during the procedure. Fat liquefaction occurred in 2 patients. Edema of the neck skin flap presented as lack of a suprasternal notch. No skin numbness occurred. No patient required postoperative pain medication. All patients were extremely satisfied with the cosmetic results. Conclusions: This new method of establishing a WS between the two layers of the SPF and underneath the IL is simple and fast, provides good exposure, yields less postoperative pain, and has a lower risk of skin burn.
Introduction
E
ndoscopic thyroidectomy (ET) for patients with thyroid disease is an effective procedure that yields an excellent cosmetic result.1,2 Since Hu¨scher et al.3 first reported successful endoscopic neck surgery in 1997, several endoscopic thyroid surgical techniques have been developed.4–8 According to the placement of incisions, the ET approach may be classified as cervical or extracervical. The extracervical approach has been further classified into supraclavicular, anterior chest wall, axillary, and periareolar approaches.9,10 Among these, the bilateral areolar approach (BAA) offers the advantages of minimal invasiveness and superior aesthetic results compared with the other approaches. This approach is particularly suitable for patients with benign thyroid disease or small-sized papillary carcinomas.11 This approach is more commonly used in China now.12 In the BAA, hydrodissection is performed using a tumescent solution injected into the subcutaneous space in the breast area. A working space (WS) is then created, using expansion rods positioned on the surface of the pectoral fascia. A subplatysmal space in the neck is dissected using an ultrasonic coagulation device.9,10,12–14 We have found that if the
tumescent solution is injected underneath the pectoral fascia, a better WS can be created under the deep layer of the deep cervical fascia (investing layer [IL]). Herein, we report our experience in ET through a BAA by creating an operative space in this new anatomic plane.
Subjects and Methods Patients From April 2012 to December 2012, 85 patients with benign thyroid nodules were treated with ET via the BAA. There were 77 women and 8 men with a mean age of 35.12 – 9.52 (range, 21–61) years. The size of the nodules was 2.5 – 1.2 (range, 1–4.5) cm. The maximum dimension of the thyroid gland on ultrasonography in patients with multinodular goiter was 5.5 – 0.8 (range, 4.2–7.5) cm. All patients chose this procedure for minimal incisional scars. Preoperative evaluations included ultrasonography, computed tomographic imaging, and direct laryngoscopy to assess vocal cord mobility. History of thyroiditis, Graves’ disease, previous neck or thyroid surgery, and irradiation were considered contraindications for ET.15
1
Department of Thyroid and Breast Surgery, Affiliated Nanhai Hospital of Southern Medical University, Foshan, People’s Republic of China. Department of Thyroid and Breast Surgery, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, People’s Republic of China. Department of Anatomy, Southern Medical University, Guangzhou, People’s Republic of China.
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Surgical procedure ET was performed using the BAA with the patient under general anesthesia. Patients were placed in a supine position with the neck extended. The tumescent solution was prepared using 1 mg of epinephrine and 75 mg of ropivacaine in 250 mL of normal saline. Three operating tunnels were subcutaneously infiltrated with the tumescent solution. A 15-mm incision was made in the medial border of the right mammary areola for the camera port and for removing specimens. Two 5-mm incisions were made in the upper margin of both breast areolas for the working ports (Fig. 1). A long needle, modified from a Veress needle, was inserted into the area of the manubrium via the camera port incision, and 30–40 mL of tumescent solution was injected followed by 50 ml of air insufflation. The WS in the chest was extended using expansion rods (10-mm blunt tip metal rods) with the upper edge reaching the area of each sternal head of the sternocleidomastoid muscle. After blunt dissection of the anterior chest wall, a 12-mm trocar was inserted. The WS was maintained using low CO2 insufflation pressure (6 mm Hg). A 30 10-mm flexible endoscope (Olympus, Tokyo, Japan) was inserted through the camera port. A 5-mm trocar was inserted into the left working port, and an ultrasonic coagulation device (Harmonic scalpel ACE; Ethicon Endo-Surgery, Cincinnati, OH) was used to dissect a WS under endoscopic guidance. When the WS in the chest wall was completely expanded, a ‘‘cat eye’’ structure could be seen through the endoscope (Fig. 2). A Harmonic scalpel was used to divide suprasternal fatty tissue between the two ‘‘cat eyes’’ until the strap muscles, which were red in color, were seen. Dissection was continued cranially above the fascia of the strap muscles to expand the WS in the neck to the level of the thyroid cartilage and to the medial edges of the sternocleidomastoid muscles (Fig. 3). After the neck WS was created, a 5-mm trocar was inserted in the right working port. The cervical linea alba between the strap muscles was incised, and the anterolateral surface of the gland was dissected free. Silk sutures (1-0) were passed through the neck skin to the strap muscles on each side to retract the strap muscles and expose the lateral aspects of the thyroid gland (Fig. 4). Partial, subtotal, near-total, or total lo-
FIG. 1. The positions of the trocar and the ‘‘Y’’ shape of the dissection area in the chest and neck by expansion rods.
FIG. 2. In dissection of the suprasternal space (SS), the ‘‘cat eyes’’ (CE) can be seen. AJV, anterior jugular veins; IL, investing layer; SCM, sternocleidomastoid muscle.
bectomies were performed as clinically indicated. The resected specimen was retrieved through the 15-mm port. Frozen sections of the resected specimen were performed for pathological confirmation. The strap muscles were re-approximated using 3-0 polyglactin 910 (Vicryl; Ethicon, Inc., Somerville, NJ) sutures. A small drainage was placed in the thyroid fossa and brought out through the right or left working port. The other two incisions were closed using 5-0 Vicryl sutures. Results The time for creating a WS was 7.2 – 2.1 (range, 5–12) minutes. No hemorrhage occurred during this process. Frozen sections revealed one malignancy, which was converted to conventional open surgery. Endoscopic subtotal, near-total, and hemithyroidectomies were performed in 29 cases, 38 cases, and 18 cases, respectively. The mean operative time
FIG. 3. Dissection of the neck working space through the plane between the investing layer (IL) and strap muscles (SM). SCM, sternocleidomastoid muscle; SS, suprasternal space.
A NOVEL METHOD FOR CREATING WORKING SPACE FOR ET
FIG. 4. Silk sutures were used to retract the strap muscles (SM) and expose the thyroid gland. SCM, sternocleidomastoid muscle. was 75.1 – 18.5 (range, 45–180) minutes. Estimated blood loss was 10.1 – 6.5 (range, 1–50) mL. The overall volume of postoperative drainage was 121.25 – 54.36 (range, 64–217) mL. No transient or permanent hypocalcemia, recurrent laryngeal nerve palsy, seroma, skin ecchymosis, or burn occurred. Fat liquefaction occurred in 2 patients. All patients developed edema of the neck skin flap presenting as loss of the suprasternal notch, which resolved within 1 month. No numbness of the neck or chest skin was observed. No patients required postoperative pain medicine. All patients were extremely satisfied with the cosmetic results. Discussion Anatomy of the neck and chest fascia The creation of a WS is an important step in ET, especially for beginners. The rest of the ET procedure is similar to open surgery. However, few reports have focused on the methodology of creating a WS. The deepest anatomical structure described in previous methods was the superficial fascia of the anterior thoracic region, which continues into the neck.16 The pectoral fascia is continuous with the IL of the neck superiorly.17 Therefore, a natural space can be found between the superficial fascia in the chest and the pectoral fascia. Dissection within this space will lead to the subplatysmal space between the superficial cervical fascia and the IL. In this study, we describe a new technique to establish the chest WS underneath the deep surface of the pectoral fascia over the manubrium and then entering the space deep to the IL in the neck. The relevant anatomical structures were confirmed intraoperatively as well as in our cadaver studies. A literature review of anatomical studies has shown that the pectoral fascia originates from the clavicle and divides into two layers to envelop the pectoral major muscle. The deep layer of the pectoral fascia inserts onto the sternum, whereas its superficial layer goes beyond the sternum to continue with the pectoral fascia on the contralateral side.18 The superficial layer is also called the superficial pectoral fascia (SPF).19 The thickness of the SPF is reported to be
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1.14–2.97 mm, and the SPF is considered the only layer of fascia over the sternum.18,20 We found that the SPF can be separated into two layers at the level of the manubrium: an anterior layer and a posterior layer. This differs from the superficial layer and deep layer of the pectoral fascia described in previous anatomy studies. The posterior layer of the SPF is denser than the anterior layer. An obvious space exists between the two layers. A potential space also exists between the posterior layer and the manubrium, but this is narrower than the former space. The anterior layer of the SPF extends to the neck and continues with the IL, whereas the posterior layer continues with the muscular fasciae of the sternocleidomastoid muscle. The middle part of the anterior layer and posterior layer at the level of the suprasternal fossa is the suprasternal space. The structures identified in the cadaver dissection confirmed our endoscopic finding (Fig. 5). Our anatomic findings differ from traditional anatomical descriptions. The IL has been reported to split into two layers. The superficial and deep layers are attached to the anterior and posterior borders of the manubrium.21 We found an obvious space between the superficial layer of the IL and the manubrium. This is also the space between the two layers of the SPF. The layers could be easily separated by injecting dissection fluid and inserting expansion rods. The existence of this space is important for the ET procedure because a WS can be created through this gap, and it challenges the previous view of the absence of an anatomical plane for ET via BAA. Advantage of establishing a WS deep to the IL The WS established above the IL is similar to the anatomical plane found during open surgery. As the operation is performed using endoscopic techniques, the following disadvantages might exist: The IL is thick and is under tension, so it is difficult to incise.
FIG. 5. Structures identified in cadaver dissection. A-SPF, anterior layer of the superficial pectoral fascia; CE, ‘‘cat eye’’; IL, investing layer; P-SPF, posterior layer of the superficial pectoral fascia; SCF, superficial cervical fascia; SCM, sternocleidomastoid muscle; SS, suprasternal space.
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FIG. 6. Schematic diagram of a cross section of the suprasternal space. 1A and 1B are the superficial layer and the deep layer of the investing layer, respectively. The dotted line is the path to dissecting the suprasternal space.
The dense IL makes it difficult to retract the anterior strap muscles for exposure. There are dense connections between the IL and the superficial cervical fascia, making it more difficult and time consuming to create a gap between these two layers. When the dissection plane is superficial, it is easy to burn the skin, which has been frequently reported in the literature.21,22 The only advantage of using this WS is that it is not necessary to divide the anterior jugular veins. In contrast, if the WS is established behind the IL, the procedure will be simpler and faster with good exposure and better protection of the skin because of the following advantages: There is a large potential space in this anatomical plane. The IL can prevent thermal injury to the skin by the ultrasonic scalpel. The strap muscles can be retracted easily. In our experience, this WS can be created with 5–12 minutes, and there has been no incidence of skin burn. In addition, edema of the skin flap and numbness seldom occurred, and postoperative pain was reduced. This is most likely the result of the more contained thoracic WS and deeper neck WS. This path of dissection does not disrupt the intercostal nerves in the thorax and subcutaneous sensory nerves in the neck. Creating a WS in the chest wall Based on our anatomical findings of the fascias in the chest and neck, surgeons need to enter the space underneath the IL from the space between the anterior and posterior layers of the SPF.
FIG. 7. Schematic diagram of the midsagittal anatomical structure of the neck and chest. 1A and 1B are the superficial layer and the deep layer of the investing layer, respectively. 2A and 2B are the anterior layer and the posterior layer of the superficial pectoral fascia, respectively. The dotted line is the path to dissecting the working space in the neck.
However, in the BAA, a blind puncture has to be performed first to dissect the WS. Therefore, precise positioning of the injection needle in the space between the anterior and posterior layers of the SPF can be an issue. The blunt tip of the injection needle must be pushed up onto the manubrium and slid forward 0.5–1 cm to enter this space. This is a safe maneuver because the posterior layer is dense and hard to penetrate with a blunt needle. In addition, the potential space between the posterior layer and the manubrium is very narrow; therefore it is unlikely for the side hole of the needle to enter this layer. The signs of correct needle positioning include: The skin is uniformly and evenly elevated over the manubrium. Injected air spreads along the clavicles and sternocleidomastoid muscles on both sides. Expansion rods can easily expand the space over the sternum and reach the area of the sternocleidomastoid head on both sides. The WS in the chest is about 5 · 5 cm and is limited by the width of the manubrium. A larger WS is unnecessary, as it would increase CO2 absorption23 and increase the risk of injuring the internal mammary perforators along the sternal borders.20 Creating a WS in the neck After the WS is established over the manubrium, the ‘‘cat eye’’ structures can be seen. The ‘‘cat eye’’ is formed by the expansion rods over the sternocleidomastoid muscles on both sides. The anterior structure of the ‘‘cat eye’’ is the IL. The posterior border is formed by the sternocleidomastoid muscle and its fascia. The potential space between the ‘‘cat eyes’’ is the suprasternal space (Fig. 6).
A NOVEL METHOD FOR CREATING WORKING SPACE FOR ET The ‘‘cat eyes’’ are the landmark for surgeons to locate the correct space. Between the ‘‘cat eyes’’ is the suprasternal space in which a branch of the anterior jugular vein can be seen. This vein needs to be divided. Then the deep layer of the IL is incised until the red strap muscle with its overlying fascia is seen (Fig. 7). The anterior cervical WS is therefore created between the IL and fascia of the strap muscles. Fat tissue can be found in the suprasternal space superficial to the strap muscles, hence the description of ‘‘yellow sky and red earth’’ in endoscopic findings. We regard the suprasternal space as a natural ‘‘door’’ for entering the WS in the neck. If a surgeon creates a WS in the neck between the superficial fascia of the chest wall and the SPF, the bridging tissues between the ‘‘cat eyes’’ are mostly fiber strap, closely connected to the IL.24 The red strap muscles on the ‘‘earth’’ will not be seen. Instead, the white IL is seen on the floor. Conclusions Our technique of establishing a WS for ET via a BAA differs from the conventional method. With our technique, dissection is carried out through the space between the anterior and posterior layers of the SPF and beneath the IL in the neck. This method is simple and fast, provides good exposure, yields less postoperative pain, and avoids burn injury to the skin. This technique shows the true ‘‘minimally invasive effect’’ of ET. Disclosure Statement No competing financial interests exist. References 1. Chen XD, Peng B, Gong RX, et al. Endoscopic thyroidectomy: An evidence-based research on feasibility, safety and clinical effectiveness. Chin Med J (Engl) 2008;121:2088–2094. 2. Sasaki A, Nakajima J, Ikeda K, et al. Endoscopic thyroidectomy by the breast approach: A single institution’s 9-year experience. World J Surg 2008;32:381–385. 3. Hu¨scher CS, Chiodini S, Napolitano C, et al. Endoscopic right thyroid lobectomy. Surg Endosc 1997;11:877. 4. Miccoli P, Pinchera A, Cecchini G, et al. Minimally invasive, video-assisted parathyroid surgery for primary hyperparathyroidism. J Endocrinol Invest 1997;20:429–430. 5. Bellantone R, Lombardi CP, Raffaelli M, et al. Minimally invasive, totally gasless video-assisted thyroid lobectomy. Am J Surg 1999;177:342–343. 6. Ikeda Y, Takami H, Niimi M, et al. Endoscopic thyroidectomy by the axillary approach. Surg Endosc 2001;15:1362–1364. 7. Yamashita H, Watanabe S, Koike E, et al. Video-assisted thyroid lobectomy through a small wound in the submandibular area. Am J Surg 2002;183:286–289. 8. Kang SW, Jeong JJ, Yun JS, et al. Robot-assisted endoscopic surgery for thyroid cancer: Experience with the first 100 patients. Surg Endosc 2009;11:2399–2406. 9. Chowbey PK, Soni V, Khullar R, et al. Endoscopic neck surgery. J Minim Access Surg 2007;3:3–7.
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10. Slotema ET, Sebag F, Henry JF. What is the evidence for endoscopic thyroidectomy in the management of benign thyroid disease? World J Surg 2008;32:1325–1332. 11. Hur SM, Kim SH, Lee SK, et al. New endoscopic thyroidectomy with the bilateral areolar approach: A comparison with the bilateral axillo-breast approach. Surg Laparosc Endosc Percutan Tech 2011;21:e219–e224. 12. Chen GZ, Zhang X, Shi WL, et al. Systematic comparison of cervical and extra-cervical surgical approaches for endoscopic thyroidectomy. Surg Today 2012;42:835–841. 13. Bhargav PRK, Amar V. Operative technique of endoscopic thyroidectomy: A narration of general principles. Indian J Surg 2013;75:216–219. 14. Cao F, Xie B, Cui B, Xu D. Endoscopic vs. conventional thyroidectomy for the treatment of benign thyroid tumors: A retrospective study of a 4-year experience. Exp Ther Med 2011;2:661–666. 15. Hong HJ, Kim WS, Koh YW, et al. Endoscopic thyroidectomy via an axillo-breast approach without gas insufflation for benign thyroid nodules and micropapillary carcinomas: Preliminary results. Yonsei Med J 2011;52:643–654. 16. Philip R, John TH. TNM Staging Atlas. Hagerstown, MD: Lippincott Williams & Wilkins, 2007:469. 17. Robert BT. The cyclopaedia of anatomy and physiology. London: Sherwood, 1852:230. 18. Stecco A, Masiero S, Macchi V, et al. The pectoral fascia: Anatomical and histological study. J Bodyw Mov Ther 2009;13:255–261. 19. Hwang K, Kim DJ. Anatomy of pectoral fascia in relation to subfascial mammary augmentation. Ann Plast Surg 2005; 55:576–579. 20. Jinde L, Jianliang S, Xiaoping C, et al. Anatomy and clinical significance of pectoral fascia. Plast Reconstr Surg 2006;118: 1557–1560. 21. Cho YU, Park IJ, Choi KH, et al. Gasless endoscopic thyroidectomy via an anterior chest wall approach using a flaplifting system. Yonsei Med J 2007;48:480–487. 22. Ikeda Y, Takami H, Tajima G, et al. Total endoscopic thyroidectomy: Axillary or anterior chest approach. Biomed Pharmacother 2002;56(Suppl 1):72s–78s. 23. Wang M, Zhang T, Mao Z, et al. Effect of endoscopic thyroidectomy via anterior chest wall approach on treatment of benign thyroid tumors. J Laparoendosc Adv Surg Tech A 2009;19:149–152. 24. Nash L, Nicholson HD, Zhang M. Does the investing layer of the deep cervical fascia exist? Anesthesiology 2005;103:962–968.
Address correspondence to: Tao Wu, MS Department of Anatomy Southern Medical University 1838 Guangzhou Avenue Guangzhou, 510515 People’s Republic of China E-mail: [email protected]
A Novel Method for Creating Working Space During Endoscopic Thyroidectomy via Bilateral Areolar Approach Yi-Hong Tan, MS,1 Guo-Neng Du, MS,1 Yu-Gen Xiao, MS,1 Wan-Shou Qiu, MS,2 and Tao Wu, MS 3
Abstract
Background: Endoscopic thyroidectomy (ET) can be performed through the bilateral areolar approach (BAA). A working space (WS) is typically created on the surface of the pectoral fascia in the chest wall and in the subplatysmal space in the neck. There are several limitations of using this WS. The aim of this study was to establish a new WS for ET. Subjects and Methods: A retrospective review was performed on 85 patients with benign thyroid nodules who had undergone ET through a BAA. A WS was created between the anterior and poster layers of the superficial pectoral fascia (SPF) in the chest and underneath the deep layer of the investing layer (IL) in the neck. Results: The time for creating the WS was 7.2 – 2.1 (range, 5–12) minutes. No hemorrhage occurred during the procedure. Fat liquefaction occurred in 2 patients. Edema of the neck skin flap presented as lack of a suprasternal notch. No skin numbness occurred. No patient required postoperative pain medication. All patients were extremely satisfied with the cosmetic results. Conclusions: This new method of establishing a WS between the two layers of the SPF and underneath the IL is simple and fast, provides good exposure, yields less postoperative pain, and has a lower risk of skin burn.
Introduction
E
ndoscopic thyroidectomy (ET) for patients with thyroid disease is an effective procedure that yields an excellent cosmetic result.1,2 Since Hu¨scher et al.3 first reported successful endoscopic neck surgery in 1997, several endoscopic thyroid surgical techniques have been developed.4–8 According to the placement of incisions, the ET approach may be classified as cervical or extracervical. The extracervical approach has been further classified into supraclavicular, anterior chest wall, axillary, and periareolar approaches.9,10 Among these, the bilateral areolar approach (BAA) offers the advantages of minimal invasiveness and superior aesthetic results compared with the other approaches. This approach is particularly suitable for patients with benign thyroid disease or small-sized papillary carcinomas.11 This approach is more commonly used in China now.12 In the BAA, hydrodissection is performed using a tumescent solution injected into the subcutaneous space in the breast area. A working space (WS) is then created, using expansion rods positioned on the surface of the pectoral fascia. A subplatysmal space in the neck is dissected using an ultrasonic coagulation device.9,10,12–14 We have found that if the
tumescent solution is injected underneath the pectoral fascia, a better WS can be created under the deep layer of the deep cervical fascia (investing layer [IL]). Herein, we report our experience in ET through a BAA by creating an operative space in this new anatomic plane.
Subjects and Methods Patients From April 2012 to December 2012, 85 patients with benign thyroid nodules were treated with ET via the BAA. There were 77 women and 8 men with a mean age of 35.12 – 9.52 (range, 21–61) years. The size of the nodules was 2.5 – 1.2 (range, 1–4.5) cm. The maximum dimension of the thyroid gland on ultrasonography in patients with multinodular goiter was 5.5 – 0.8 (range, 4.2–7.5) cm. All patients chose this procedure for minimal incisional scars. Preoperative evaluations included ultrasonography, computed tomographic imaging, and direct laryngoscopy to assess vocal cord mobility. History of thyroiditis, Graves’ disease, previous neck or thyroid surgery, and irradiation were considered contraindications for ET.15
1
Department of Thyroid and Breast Surgery, Affiliated Nanhai Hospital of Southern Medical University, Foshan, People’s Republic of China. Department of Thyroid and Breast Surgery, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, People’s Republic of China. Department of Anatomy, Southern Medical University, Guangzhou, People’s Republic of China.
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Surgical procedure ET was performed using the BAA with the patient under general anesthesia. Patients were placed in a supine position with the neck extended. The tumescent solution was prepared using 1 mg of epinephrine and 75 mg of ropivacaine in 250 mL of normal saline. Three operating tunnels were subcutaneously infiltrated with the tumescent solution. A 15-mm incision was made in the medial border of the right mammary areola for the camera port and for removing specimens. Two 5-mm incisions were made in the upper margin of both breast areolas for the working ports (Fig. 1). A long needle, modified from a Veress needle, was inserted into the area of the manubrium via the camera port incision, and 30–40 mL of tumescent solution was injected followed by 50 ml of air insufflation. The WS in the chest was extended using expansion rods (10-mm blunt tip metal rods) with the upper edge reaching the area of each sternal head of the sternocleidomastoid muscle. After blunt dissection of the anterior chest wall, a 12-mm trocar was inserted. The WS was maintained using low CO2 insufflation pressure (6 mm Hg). A 30 10-mm flexible endoscope (Olympus, Tokyo, Japan) was inserted through the camera port. A 5-mm trocar was inserted into the left working port, and an ultrasonic coagulation device (Harmonic scalpel ACE; Ethicon Endo-Surgery, Cincinnati, OH) was used to dissect a WS under endoscopic guidance. When the WS in the chest wall was completely expanded, a ‘‘cat eye’’ structure could be seen through the endoscope (Fig. 2). A Harmonic scalpel was used to divide suprasternal fatty tissue between the two ‘‘cat eyes’’ until the strap muscles, which were red in color, were seen. Dissection was continued cranially above the fascia of the strap muscles to expand the WS in the neck to the level of the thyroid cartilage and to the medial edges of the sternocleidomastoid muscles (Fig. 3). After the neck WS was created, a 5-mm trocar was inserted in the right working port. The cervical linea alba between the strap muscles was incised, and the anterolateral surface of the gland was dissected free. Silk sutures (1-0) were passed through the neck skin to the strap muscles on each side to retract the strap muscles and expose the lateral aspects of the thyroid gland (Fig. 4). Partial, subtotal, near-total, or total lo-
FIG. 1. The positions of the trocar and the ‘‘Y’’ shape of the dissection area in the chest and neck by expansion rods.
FIG. 2. In dissection of the suprasternal space (SS), the ‘‘cat eyes’’ (CE) can be seen. AJV, anterior jugular veins; IL, investing layer; SCM, sternocleidomastoid muscle.
bectomies were performed as clinically indicated. The resected specimen was retrieved through the 15-mm port. Frozen sections of the resected specimen were performed for pathological confirmation. The strap muscles were re-approximated using 3-0 polyglactin 910 (Vicryl; Ethicon, Inc., Somerville, NJ) sutures. A small drainage was placed in the thyroid fossa and brought out through the right or left working port. The other two incisions were closed using 5-0 Vicryl sutures. Results The time for creating a WS was 7.2 – 2.1 (range, 5–12) minutes. No hemorrhage occurred during this process. Frozen sections revealed one malignancy, which was converted to conventional open surgery. Endoscopic subtotal, near-total, and hemithyroidectomies were performed in 29 cases, 38 cases, and 18 cases, respectively. The mean operative time
FIG. 3. Dissection of the neck working space through the plane between the investing layer (IL) and strap muscles (SM). SCM, sternocleidomastoid muscle; SS, suprasternal space.
A NOVEL METHOD FOR CREATING WORKING SPACE FOR ET
FIG. 4. Silk sutures were used to retract the strap muscles (SM) and expose the thyroid gland. SCM, sternocleidomastoid muscle. was 75.1 – 18.5 (range, 45–180) minutes. Estimated blood loss was 10.1 – 6.5 (range, 1–50) mL. The overall volume of postoperative drainage was 121.25 – 54.36 (range, 64–217) mL. No transient or permanent hypocalcemia, recurrent laryngeal nerve palsy, seroma, skin ecchymosis, or burn occurred. Fat liquefaction occurred in 2 patients. All patients developed edema of the neck skin flap presenting as loss of the suprasternal notch, which resolved within 1 month. No numbness of the neck or chest skin was observed. No patients required postoperative pain medicine. All patients were extremely satisfied with the cosmetic results. Discussion Anatomy of the neck and chest fascia The creation of a WS is an important step in ET, especially for beginners. The rest of the ET procedure is similar to open surgery. However, few reports have focused on the methodology of creating a WS. The deepest anatomical structure described in previous methods was the superficial fascia of the anterior thoracic region, which continues into the neck.16 The pectoral fascia is continuous with the IL of the neck superiorly.17 Therefore, a natural space can be found between the superficial fascia in the chest and the pectoral fascia. Dissection within this space will lead to the subplatysmal space between the superficial cervical fascia and the IL. In this study, we describe a new technique to establish the chest WS underneath the deep surface of the pectoral fascia over the manubrium and then entering the space deep to the IL in the neck. The relevant anatomical structures were confirmed intraoperatively as well as in our cadaver studies. A literature review of anatomical studies has shown that the pectoral fascia originates from the clavicle and divides into two layers to envelop the pectoral major muscle. The deep layer of the pectoral fascia inserts onto the sternum, whereas its superficial layer goes beyond the sternum to continue with the pectoral fascia on the contralateral side.18 The superficial layer is also called the superficial pectoral fascia (SPF).19 The thickness of the SPF is reported to be
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1.14–2.97 mm, and the SPF is considered the only layer of fascia over the sternum.18,20 We found that the SPF can be separated into two layers at the level of the manubrium: an anterior layer and a posterior layer. This differs from the superficial layer and deep layer of the pectoral fascia described in previous anatomy studies. The posterior layer of the SPF is denser than the anterior layer. An obvious space exists between the two layers. A potential space also exists between the posterior layer and the manubrium, but this is narrower than the former space. The anterior layer of the SPF extends to the neck and continues with the IL, whereas the posterior layer continues with the muscular fasciae of the sternocleidomastoid muscle. The middle part of the anterior layer and posterior layer at the level of the suprasternal fossa is the suprasternal space. The structures identified in the cadaver dissection confirmed our endoscopic finding (Fig. 5). Our anatomic findings differ from traditional anatomical descriptions. The IL has been reported to split into two layers. The superficial and deep layers are attached to the anterior and posterior borders of the manubrium.21 We found an obvious space between the superficial layer of the IL and the manubrium. This is also the space between the two layers of the SPF. The layers could be easily separated by injecting dissection fluid and inserting expansion rods. The existence of this space is important for the ET procedure because a WS can be created through this gap, and it challenges the previous view of the absence of an anatomical plane for ET via BAA. Advantage of establishing a WS deep to the IL The WS established above the IL is similar to the anatomical plane found during open surgery. As the operation is performed using endoscopic techniques, the following disadvantages might exist: The IL is thick and is under tension, so it is difficult to incise.
FIG. 5. Structures identified in cadaver dissection. A-SPF, anterior layer of the superficial pectoral fascia; CE, ‘‘cat eye’’; IL, investing layer; P-SPF, posterior layer of the superficial pectoral fascia; SCF, superficial cervical fascia; SCM, sternocleidomastoid muscle; SS, suprasternal space.
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FIG. 6. Schematic diagram of a cross section of the suprasternal space. 1A and 1B are the superficial layer and the deep layer of the investing layer, respectively. The dotted line is the path to dissecting the suprasternal space.
The dense IL makes it difficult to retract the anterior strap muscles for exposure. There are dense connections between the IL and the superficial cervical fascia, making it more difficult and time consuming to create a gap between these two layers. When the dissection plane is superficial, it is easy to burn the skin, which has been frequently reported in the literature.21,22 The only advantage of using this WS is that it is not necessary to divide the anterior jugular veins. In contrast, if the WS is established behind the IL, the procedure will be simpler and faster with good exposure and better protection of the skin because of the following advantages: There is a large potential space in this anatomical plane. The IL can prevent thermal injury to the skin by the ultrasonic scalpel. The strap muscles can be retracted easily. In our experience, this WS can be created with 5–12 minutes, and there has been no incidence of skin burn. In addition, edema of the skin flap and numbness seldom occurred, and postoperative pain was reduced. This is most likely the result of the more contained thoracic WS and deeper neck WS. This path of dissection does not disrupt the intercostal nerves in the thorax and subcutaneous sensory nerves in the neck. Creating a WS in the chest wall Based on our anatomical findings of the fascias in the chest and neck, surgeons need to enter the space underneath the IL from the space between the anterior and posterior layers of the SPF.
FIG. 7. Schematic diagram of the midsagittal anatomical structure of the neck and chest. 1A and 1B are the superficial layer and the deep layer of the investing layer, respectively. 2A and 2B are the anterior layer and the posterior layer of the superficial pectoral fascia, respectively. The dotted line is the path to dissecting the working space in the neck.
However, in the BAA, a blind puncture has to be performed first to dissect the WS. Therefore, precise positioning of the injection needle in the space between the anterior and posterior layers of the SPF can be an issue. The blunt tip of the injection needle must be pushed up onto the manubrium and slid forward 0.5–1 cm to enter this space. This is a safe maneuver because the posterior layer is dense and hard to penetrate with a blunt needle. In addition, the potential space between the posterior layer and the manubrium is very narrow; therefore it is unlikely for the side hole of the needle to enter this layer. The signs of correct needle positioning include: The skin is uniformly and evenly elevated over the manubrium. Injected air spreads along the clavicles and sternocleidomastoid muscles on both sides. Expansion rods can easily expand the space over the sternum and reach the area of the sternocleidomastoid head on both sides. The WS in the chest is about 5 · 5 cm and is limited by the width of the manubrium. A larger WS is unnecessary, as it would increase CO2 absorption23 and increase the risk of injuring the internal mammary perforators along the sternal borders.20 Creating a WS in the neck After the WS is established over the manubrium, the ‘‘cat eye’’ structures can be seen. The ‘‘cat eye’’ is formed by the expansion rods over the sternocleidomastoid muscles on both sides. The anterior structure of the ‘‘cat eye’’ is the IL. The posterior border is formed by the sternocleidomastoid muscle and its fascia. The potential space between the ‘‘cat eyes’’ is the suprasternal space (Fig. 6).
A NOVEL METHOD FOR CREATING WORKING SPACE FOR ET The ‘‘cat eyes’’ are the landmark for surgeons to locate the correct space. Between the ‘‘cat eyes’’ is the suprasternal space in which a branch of the anterior jugular vein can be seen. This vein needs to be divided. Then the deep layer of the IL is incised until the red strap muscle with its overlying fascia is seen (Fig. 7). The anterior cervical WS is therefore created between the IL and fascia of the strap muscles. Fat tissue can be found in the suprasternal space superficial to the strap muscles, hence the description of ‘‘yellow sky and red earth’’ in endoscopic findings. We regard the suprasternal space as a natural ‘‘door’’ for entering the WS in the neck. If a surgeon creates a WS in the neck between the superficial fascia of the chest wall and the SPF, the bridging tissues between the ‘‘cat eyes’’ are mostly fiber strap, closely connected to the IL.24 The red strap muscles on the ‘‘earth’’ will not be seen. Instead, the white IL is seen on the floor. Conclusions Our technique of establishing a WS for ET via a BAA differs from the conventional method. With our technique, dissection is carried out through the space between the anterior and posterior layers of the SPF and beneath the IL in the neck. This method is simple and fast, provides good exposure, yields less postoperative pain, and avoids burn injury to the skin. This technique shows the true ‘‘minimally invasive effect’’ of ET. Disclosure Statement No competing financial interests exist. References 1. Chen XD, Peng B, Gong RX, et al. Endoscopic thyroidectomy: An evidence-based research on feasibility, safety and clinical effectiveness. Chin Med J (Engl) 2008;121:2088–2094. 2. Sasaki A, Nakajima J, Ikeda K, et al. Endoscopic thyroidectomy by the breast approach: A single institution’s 9-year experience. World J Surg 2008;32:381–385. 3. Hu¨scher CS, Chiodini S, Napolitano C, et al. Endoscopic right thyroid lobectomy. Surg Endosc 1997;11:877. 4. Miccoli P, Pinchera A, Cecchini G, et al. Minimally invasive, video-assisted parathyroid surgery for primary hyperparathyroidism. J Endocrinol Invest 1997;20:429–430. 5. Bellantone R, Lombardi CP, Raffaelli M, et al. Minimally invasive, totally gasless video-assisted thyroid lobectomy. Am J Surg 1999;177:342–343. 6. Ikeda Y, Takami H, Niimi M, et al. Endoscopic thyroidectomy by the axillary approach. Surg Endosc 2001;15:1362–1364. 7. Yamashita H, Watanabe S, Koike E, et al. Video-assisted thyroid lobectomy through a small wound in the submandibular area. Am J Surg 2002;183:286–289. 8. Kang SW, Jeong JJ, Yun JS, et al. Robot-assisted endoscopic surgery for thyroid cancer: Experience with the first 100 patients. Surg Endosc 2009;11:2399–2406. 9. Chowbey PK, Soni V, Khullar R, et al. Endoscopic neck surgery. J Minim Access Surg 2007;3:3–7.
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Address correspondence to: Tao Wu, MS Department of Anatomy Southern Medical University 1838 Guangzhou Avenue Guangzhou, 510515 People’s Republic of China E-mail: [email protected]
