The Surgical Planes And Anatomic Landmarks During Endoscopic Thyroidectomy

BackgroundThe development of laparoscopic surgery has spawned the new field of study, laparoscopic anatomy. In the field of abdominal surgery, the traditional approach of open surgery and related surgical anatomy are well established, while laparoscopic surgery and correlative laparoscopic anatomy are still under study. Endoscopic thyroidectomy (ET) was carried out since nearly 20 years ago. But few study on anatomy research of ET was found from information retrieval. The following studies were research work done by us in order to find out the surgical planes and anatomic landmarks in ET, which could guide surgeons to take ET operation safely. We did the work both by autopsy and clinical research.Part 1 Autopsy Rearch of Endoscopic Thyroidectomy AnatomyAimIn this study, we imitated the breast approach of live ET procedure on cadavers, in order to find out the structure layer of procedure and position relationships of structures. The aim is to do some initial research about anatomy in ET.MethodsThree cadavers, of which one was fresh and two were fixed with 10% formalin, donated to department of anatomy of the Southern Medical University of Guangzhou were studied. None had signs or history of thyroid diseases. ET procedures were taken on them imitating the approach of live procedure without using carbon dioxide, instead of procedure space unwrapped. Photos were taken when dissecting. Results1. Structure layers1.1 The procedure space of ET on the anterior chest was between the superficial fascia and the deep fascia.1.2 The procedure space of ET on the neck was between the platysma muscle and the superficial layer of deep fascia. The platysma on neck adhered tightly to superficial fascia, which was continuous from superior breast to neck.1.3 The pectoralis major fascia on breast and superficial layer of deep fascia on neck were continuous.1.4 The ET dissecting triangle, which was between the muscle strip and thyroid gland, was an important layer to search the inferior thyroid vessels and middle thyroid vein.1.5 The parathyroid gland was wrapped within fibrous capsule of thyroid gland. A loose space could be found between thyroid gland and parathyroid gland.1.6 During the procedure of the central lymph node dissection, lymph nodes group had its own fascia wrapped, and the spaces between thymus gland and lymph nodes of level VI could be found.2. Structure position relationships2.1 The recurrent laryngeal nerve could be found beneath inferior parathyroid gland.2.2 A vessel could be found above and parallel with RLN.2.3 The superior parathyroid gland could be found adjacent to middle thyroid vein and on the same horizontal level with that of recurrent laryngeal nerve going in to larynx.2.4 The the external branch of superior laryngeal nerve was stick to cricothyroid muscle, and went into larynx during the middle and inferior part of thyroid cartilage.DiscussionThe surgical plane during live ET procedure could be proofed appropriate by the research of the structure layers of the anterior chest and neck in this study. The loose spaces found in our study could guide surgeons how to protect important structures, such as parathyroid glands and recurrent laryngeal nerves, during the central lymph node dissection of ET. These specific structure position relationships found in our study could guide surgeons to operate safely during ET without injury of the important strutures, as well as lead us to find the anatomic landmarks in live ET procedure.Part 2 Clinical Anatomy Rearch of Endoscopic ThyroidectomyAimBecause of lacking of tactile sensation and limitation of procedure direction, how to find appropriate surgical planes and anatomic landmarks in ET is of importance to surgeons. This study is aim to find these in live ET procedure.MethodsThe surgical plane and anatomic landmark were observed on endoscopic eyesight in 83 consecutive cases (74 females and 9 males,69 right lobes and 30 left lobes) of living endoscopic thyroidectomy by anterior breast approach.7 cases were diagnosed as malignant tumour of single lobe by frozen.Results1. Surgical planes1.1 The appropriate procedure spaces were between the superficial fascia and pectoralis major fascia on beast, and between platysma and superficial layer of deep fascia on neck, which of the two layers were continuous.1.2 The ET dissecting triangle was the space between the muscle strip and thyroid lobe, which could be the surgical plane for finding the inferior thyroid vascular (100.0%) and the middle thyroid vein (100.0%). 2. Landmarks2.1 The inferior parathyroid gland could be found under the inferior thyroid artery (92.5%). Therefore, the inferior thyroid artery could be landmark for finding the inferior parathyroid gland.2.2 The recurrent laryngeal nerve could be found under the inferior parathyroid gland (85.7%). Therefore, the inferior parathyroid gland could be landmark for finding the recurrent laryngeal nerve.2.3 The superior parathyroid gland could be found adjacent to the middle thyroid vein (90.0%). Therefore, the middle thyroid vein could be landmark for finding the superior parethyroid gland.2.4 The thyroid region segment of exposed recurrent laryngeal nerves went into larynx posterior inferior the thyroid cartilage, above which a vessel (V1) perpendicular to recurrent laryngeal nerve, as a landmark to find laryngeal nerve, went from the thyroid lobe to larynx (100.0%). Sometimes a vascular (V2) above and parallel with the recurrent laryngeal nerve could be found in tracheoesophageal groove (40.0%), which could be another landmark to found the recurrent laryngeal nerve.DiscussionDue to small space and single procedure direction (from caudal side to head side) during ET operation, the surgical planes and anatomic landmarks are particularly important for the surgeons. The recurrent laryngeal nerve and the parathyroid gland would be protected during ET following the surgical planes and anatomic landmarks we observed.ConclusionIn the field of thyroidectomy, endoscopic surgery has become increasingly popular because of its excellent cosmetic result post operation. Systematic anatomy on ET can provide surgeons with a clear idea to design their operations of different tumor position during ET, which is particularly important for practicing novice surgeons. Laparoscopic anatomy is a basic curriculum for laparoscopic surgeons, and will certainly become an important new subject as the use of laparoscopic procedures increases.