Natural orifice surgery on thyroid gland: totally transoral video-assisted thyroidectomy (TOVAT): report of first experimental results of a new surgical method.

BACKGROUND: Neck surgery is one of the newest fields of application of minimally invasive surgery. The technique of minimally invasive video-assisted thyroidectomy (MIVAT) developed by Miccoli [1] is the method that has so far become most widespread. Limiting factors of this method include the bothersome 20-mm cervical incision and consequently the specimen size to remove. Several papers describing an access outside the front neck region have been published. Such approaches are via the chest, axillary, a combined axillary bilateral breast, or a bilateral axillary breast approach [2-5]. The development of cervical scarless thyroid surgery is a great step toward better cosmetic outcomes. However, these techniques just moved the scars from the front neck region to the axilla or the chest where they are still visible. And the mentioned minimally invasive accesses as well as the conventional approaches to the thyroid gland do not respect the anatomically given surgical planes. This may result in complaints by the patients, e.g., scar development and swallowing disorders. Furthermore, the extracervical approaches do not comply with the use of the term "minimally invasive," because they are associated with an extensive dissection of the chest and neck region, thus being rather maximally invasive for the patients. The main goal of this project was the introduction of a technique of thyroid resection that fulfills the following criteria: (i. Respecting surgical planes and minimizing surgical trauma in thyroidectomy, ii. The access itself should be close to the thyroid gland to achieve a minimally invasive procedure, iii. Achieving an optimal cosmetic result may only be obtained by performing a scarless operation, iv. This optimal cosmetic result with scarless surgery should be achieved with minimal trauma, v. The minimally invasive character of this approach and the optimal cosmetic result may not be reached at the expense of patient's safety.). The technique that meets all of these criteria is the transoral access because the distance between the sublingual place and the thyroid gland is short, thus avoiding extensive dissection maneuvers. Furthermore, the mouth mucosa can be sutured without difficulties and repairs itself without leaving any visible scars. Feasibility of the transoral access has been recently demonstrated by a member of our group in a porcine model by using a modified axilloscope [6]. However, the described technique is a hybrid one because an additional medial access (3.5-mm incision) 15-mm below the larynx was necessary for the insertion of a fixation forceps through a trocar. The main goal of our project was the investigation and introduction of a technique of totally endoscopic thyroid resection that is minimally invasive and safe for the patient and at the same time cosmetically optimal (scarless). METHODS: For this purpose, a total of five human cadavers were used. In three cadavers, safety and reproducibility to reach and resect the thyroid gland was assessed according to a defined road map. At the end of the procedure, the cadavers were dissected to evaluate all defined anatomical key structures regarding possible injuries and also allow an evaluation of the surgery performed. The TOVAT itself was performed on two more human cadavers with the help of one 5-mm and two 3-mm trocars that were introduced through the mouth floor and the vestibulum of the mouth subplatysmal. A working space was created by insufflating CO(2) at a pressure of 4-6 mmHg ("air dissection"). Surgical dissection of the further working space was realized with 3-mm bipolar scissors. The procedure consists of the following steps: (i. Patient in supine position and nasotracheal intubation, ii. 5-mm small incision between the carunculae sublinguales, iii. Penetration through the mouth floor along the superficial fascia colli with a blunt instrument, iv. Insertion of a 5-mm trocar, v. Blunt dissection subplatysmal by CO(2) insufflation ("air dissection"), vi. CO(2) insufflation (4-6 mmHg) and creation of a working space, vii. Insertion of two 3-mm trocars in the vestibulum oris on the right and left side, viii. Separation of the platysma from the strap muscles approximately at level of the larynx, extending up to the suprasternal notch. Laterally, this dissection can be continued up to the medial border of the sternocleidomastoid muscles, ix. Division of the linea alba coli and exposure of the strap muscles, x. Separation of the strap muscles from the thyroid gland, xi. Isthmus transection and blunt dissection of the thyroid gland from the trachea, xii. Dissection and division of the upper pole arteries and medial thyroid vein closely to the gland, xiii. Division of branches of the inferior thyroid artery closely to the gland, xiv. If necessary, preparation of the retro-thyroidal area, including visualization of the recurrent laryngeal nerve, xv. Thyroid resection from cranial to caudal and transoral removal of the specimen through the 5-mm midline incision. If the gland is too large, the midline incision can be extended longitudinally, xvi. All three incisions are closed with absorbable sutures.) RESULTS: Description of landmarks of surgical steps and dissection of defined anatomic structures could be achieved. The subplatysmal space could be reached without any major problems within a short time. Anatomical dissection showed intact muscles and vascular structures. One-side subtotal thyroid resection could be successfully performed without any additional skin incision in 60 minutes. CONCLUSIONS: The minimally invasive aspect and the scarless character of TOVAT form the rationale for the preclinical investigation of this method in human cadavers. We could succeed in defining objective parameters, which describe the procedure in details and also allow an evaluation of the surgery performed. Access and feasibility of TOVAT could be demonstrated. The next step will be its application in living pigs before it may be applied in humans. To our knowledge of the literature, this is the first report on NOS application in thyroid surgery and also the first totally and scarless performed video-assisted thyroidectomy.

Monitoring of the recurrent laryngeal nerve in totally endoscopic thyroid surgery.

We tested the feasibility of the sublingual transoral access for thyroid resection including the monitoring of the recurrent laryngeal nerve (RLN) in a porcine model. We performed a prospective, nonrandomized proof-of-concept experimental investigation on transoral thyroid resection in a porcine model with monitoring of the RLN. Ten endoscopic transoral thyroidectomies were performed in 10 pigs using a neuromonitoring system. First, the RLN was identified visually and then confirmed with the neuromonitoring system bilaterally. A complete transoral thyroid resection was achieved in all living pigs. The average operation time was 50 min. The neuromonitoring system permitted to prove the regular function of the RLN on both sides after the removal of the thyroid gland. The pigs were observed for another 2 h postoperatively. Consequent monitoring of the RLN in endoscopic transoral thyroid resection is possible. This system can be a helpful support to identify the nerve when the anatomic situation due to using an endoscopic access is more complicated. It proved to be a safe procedure in living pigs. Our results might be useful for using the neuromonitoring system as a standard system in endoscopic thyroid surgery for the maximal safety of the patient in these new procedures.

[The natural orifice surgery concept. Vision and rationale for a paradigm shift]. / "Natural-Orifice-Surgery- (NOS-)Konzept". Vision und Rationale für einen Paradigmenwechsel.

BACKGROUND: During the 20th Century, laparoscopic surgery achieved high standards and significantly reduced morbidity. In order to make surgery simpler and safer, a new concept, natural orifice surgery (NOS), has recently been introduced. The approach to the abdominal cavity may be transoral-transgastric, transvaginal-transdouglas or transanal-transrectal. This article describes the logic behind this approach and the expected challenges. METHODS: In order to realize this goal, we founded the first European based working group on NOS. This group concentrates on the development of transdouglas procedures in women by using the transdouglas endoscopic device (TED). This is a wide, multi-channel instrument, which will enable surgery to be performed via a single entry. RESULTS: Simulation of various intra-abdominal operations, such as staging, cholecystectomy, appendectomy, myomectomy und ovarectomy, using TED has already been carried out. Practical studies are planned in the near future. CONCLUSION: The feasibility of NOS has been demonstrated in various experimental studies. We believe that this technique will create a spectrum of innovative and high quality operations and will improve patient safety.

[Total videoendoscopic thyroid resection by the axillobilateral breast approach. Operative method and first results]. / Total-videoendoskopische Strumaresektion via "axillobilateral breast approach". Operative Technik und erste Ergebnisse.

BACKGROUND: The axillobilateral breast approach (ABBA) is a procedure allowing thyroid resection without scarring at the neck. We operated on a series of 26 patients with this technique. METHOD: Via incisions at the edge of the mamilla and axilla, trocars are placed subcutaneously under the platyma. Dissection is performed bluntly and with an ultrasonographic scalpel under videoscopic control. The procedure itself corresponds to conventional surgery. The specimen is removed through the axillary trocar. RESULTS: Twenty-six female patients underwent thyroid resection using the ABBA technique. Subtotal resection was performed in 24. Mean operation times were 111 min (unilateral) and 187 min (bilateral). In none of these cases was conversion necessary. One transient recurrent laryngeal nerve palsy and one paresis of the arm plexus were found postoperatively. CONCLUSION: In selected patients the ABBA technique is feasible and safe with the mandatory radicalness. The primary aim of this method is the cosmetic result.

Laparoscopic resection for rectal cancer: outcomes in 194 patients and review of the literature.

BACKGROUND: There are few reports on laparoscopic rectum resection demonstrating its feasibility and efficacy in patients with rectal cancer. Most patient series are small, and results must be considered preliminary and medium-term. Our large prospective conducted study aimed to assess the effectiveness of a totally laparoscopic resection for rectum carcinoma with emphasis on perioperative and long-term oncological outcomes. METHODS: Between November 1992 and July 2003, 194 unselected patients were resected laparoscopically for rectal carcinoma. Patients with locally advanced rectum carcinoma (uT3/uT4) and no evidence of distant metastases were candidates for neoadjuvant chemoradiation. Adjuvant treatment was administered to patients with UICC stage II/III disease. All patients were followed up prospectively to evaluate complications and late outcomes. Survival probability analysis was performed using the Kaplan-Meier method. Study selection was made by Medline search using the following key words: rectal cancer, rectal neoplasms, laparoscopy, and resection. Single case reports and abstracts were excluded. When surgical series were reported more than once, only the most recent reports were considered and listed. RESULTS: The most common procedures were low anterior resection with total mesorectum excision in 65.5% of patients and high anterior resection in 25.3%. Average operative time was 174 min. Average number of lymph nodes removed was 25.4 and length of specimen resected was 27.6 cm. Resection was curative in 145 patients and palliative in 49 cases. UICC tumor stages were as follows: stage I: 25.2%, stage II: 27.3%, stage III: 30.4%, and stage IV: 17%. Intraoperative complications were <1% for lesions of the ureter, urinary bladder, and deferent duct. Conversion to conventional surgery was necessary in two cases (1%). The most common postoperative complication was anastomotic leakage in 13.5% of patients. There was no postoperative mortality. Follow-up evaluation ranged from 1 to 128 months with a mean of 46.1 months. The most common late complication was incisional hernia in 3.6% of patients. Port-site metastases occurred in one patient (0.5%). Tumor recurrence developed in 23 of the 145 curative resected patients (11.7% distant metastases and 4.1% local recurrence). Overall local recurrence rate was 6.7% (4.1% after curative resection and 14.3% after palliative resection). Overall survival rate was 90.6% at 1 year, 74.5% at 3 years, and 66.3% at 5 years. Overall 5-year survival rate was 76.9% after curative resection and 31.8% after palliative resection. Cancer-related survival rate was 94% at 1 year, 82.4% at 3 years, and 78.9% at 5 years. At 5 years it was 87.7% after curative resection and 48.5% after palliative resection. At 5 years, the survival rate was 100% for stage I, 94.4% for stage II, 66.6% for stage III, and 44.6% for stage IV. CONCLUSIONS: Our results and the literature review clearly demonstrate that laparoscopic resection for rectal cancer is not associated with higher morbidity and mortality. Established oncological and surgical principles are respected and long-term outcomes are at least as good as those after open surgery.

Resection and local therapy for liver metastases.

In 30-50% of patients the liver is a preferred site of distant disease for many malignant tumours. Due to the high incidence, most of the available data relate to metastases arising from colorectal primaries. Surgical resection is at present the only treatment offering potential cure. The achievable 5-year survival rate is 30%. However, only 10-15% of patients with colorectal liver metastases can undergo potentially curative liver resection. Therefore, accurate staging is an important prerequisite in selecting patients who would benefit from surgery. Recurrence of hepatic metastases after potentially curative resection occurs in up to 60% of the cases. Results demonstrate that re-resection of liver metastases can provide long-term survival rates in a carefully selected group of patients without extrahepatic disease. Because of the high rate of recurrences following an apparently curative resection several authors investigated the use of adjuvant chemotherapy (systemic, intraportal, and hepatic arterial infusion). Until recently none had shown effectiveness. Pre-operative chemotherapy seems to be a promising approach in patients with liver metastases initially considered unsuitable for radical surgery. Recently, neoadjuvant chemotherapy has been proposed as an alternative approach to conventional surgery as initial management with the aim of improving the results in resectable liver metastases. Interventional strategies (ethanol injection, cryosurgery, laser-induced thermotherapy, radio-frequency ablation) and combined modalities (surgical/interventional) are additive methods which may help to improve treatment results in the future.

Perceptual phenomena after unilateral arm amputation: a pre-post-surgical comparison.

Painful and non-painful phantom phenomena occur frequently after amputations but are rarely investigated in the perioperative stage. The goal of the present study was the assessment of phantom phenomena, pain and changes in primary somatosensory cortex prior to and after upper limb amputation. Two patients who suffered from metastatic carcinoma were examined 2 days prior to and 7 days after the amputation of an arm using comprehensive psychometric assessments and neuroelectric source imaging. Both patients reported phantom limb pain that was similar to their pre-amputation pain. In one patient, reorganization of the mouth area into the deafferented hand area took place immediately after the amputation. In the other patient reorganization had occurred prior to the amputation possibly related to non-use of the arm several years prior to the amputation.

Anomalous pancreatico-biliary junction--report of a new experimental model and review of the literature.

A model of anomalous pancreatico-biliary junction was developed and used to investigate a possible role in the development of choledochal cyst and tumors of the biliary tract. An anastomosis was constructed between an isolated pancreas-duodenal segment and the gallbladder in 20 minipigs, but the results did not show any subsequent dilatation of the biliary tract, although intestinal metaplasia was observed in 20% of the animals. The severity of the epithelial changes was proportional to the duration of the experiment and may represent a premalignant change. A critical review of all reported animal models of anomalous pancreaticobiliary junction also is provided.

A rare malformation of the pancreaticobiliary junction long common channel choledochal cyst and pancreas divisum in a patient with pancreatic cancer.

Congenital variants of the pancreaticobiliary junction are rare anomalies that are usually diagnosed in childhood because of recurrent abdominal pain and jaundice. These lesions are associated with several pancreaticobiliary diseases including pancreatitis and malignancy. We observed a rare anomaly of the pancreaticobiliary tract with a combination of several ductal malformations, i.e., choledochal cyst, long common channel and incomplete pancreas divisum in a patient with pancreatic cancer.

[Principles of curative resection of liver metastases]. / Prinzipien der kurativen Lebermetastasenresektion.

For patients with liver metastases, surgery currently represents the only possibility for cure, with a mean 5-year survival rate of 25-35%. Due to refinement in operative and anesthetic techniques and improved critical care with decreased morbidity (< 25%) and mortality (< 5%), hepatic resection is a safe and efficient procedure. Surgery has repeatedly achieved long-term disease-free survival in 20-25% of patients. However, only 10-25% of patients with colorectal liver metastases can undergo potentially curative liver resection. Therefore, accurate staging plays a pivotal role in selecting patients who would benefit from surgery. For metastatic colorectal cancer, resection offers the only potential for cure. For symptomatic neuroendocrine tumors, hepatic resection offers long-term palliation in many cases and cure in some. The role of hepatic resection for noncolorectal and nonneuroendocrine metastases, however, is less well defined. Recurrence of hepatic metastases after seemingly curative resection is observed in about 40-60% of the cases. Only 20-35% of these recurrent metastases appear to be resectable, resulting in an overall 3-year survival rate of about 30%. The morbidity and mortality from repeat hepatectomy is similar to that of first hepatic resection. All results together demonstrate that resection and re-resection of liver metastases can provide long-term survival rates and can be beneficial in a carefully selected group of patients without extrahepatic disease.

[Current therapy of bile duct cysts. I. Extrahepatic cysts]. / Aktuelle Therapie der Gallengangscysten. I. Extrahepatische Cysten.

A total of 23 patients with extrahepatic biliary cysts (11 type I, 4 type II, 4 type III and 4 type IVa according to the classification by Todani) seen at our institution in a 15-year period were reviewed with emphasis on management and long-term results at follow-up of 3 weeks-12 years. Associated hepatobiliary disease occurred in 4 patients, including one case with malignant degeneration in the cyst 23 years after cystenterostomy, and an association of a gallbladder carcinoma with a choledochocele in the other patient. Radical excision of the dilated bile duct and reconstruction by Roux-en-Y hepatico-jejunostomy was performed in 13 cases (9 type I, 3 type II and 1 type III), combined in 3 cases with an antireflux valve. All 13 operated on patients remained in good health for 6 months to 12 years. These results confirm the need for complete early excision of type I, (II) and IVa cysts at all ages before severe complications can occur. Endoscopic treatment of type III choledochocele should be limited to the management of smaller lesions.

[Cystic tumors of the pancreas]. / Cystische Tumoren des Pankreas.

Cystic neoplasms of the pancreas are rare but in the last years more frequently detected. Within a 10-year-period we treated 30 patients, including 8 serous cystadenomas, 6 mucinous cystadenomas, 12 mucinous cystadenocarcinomas, 2 cystic neuro-endocrine tumors and 1 papillary cystic tumor respectively acinar cell cyst-adenocarcinoma. 80% of the patients had symptoms, experienced abdominal pain, weight loss, weakness or abdominal mass. In eight patients the tumors had been misdiagnosed as a pancreatic pseudocyst. The correct type of cystic tumor was diagnosed by preoperative investigations only a few cases. All patients with serous or mucinous cystadenomas are well and without evident recurrence after resection of the tumor. However the survival time of malignant cystic tumors varied strongly. The curative resection of these tumors give patients the chance of long-term survival.

[Current therapy of bile duct cysts. II. Intrahepatic cysts (Caroli syndrome)]. / Aktuelle Therapie der Gallengangscysten. II. Intrahepatische Cysten (Caroli-Syndrom)

17 patients with a Caroli's syndrome are reviewed with emphasis on clinical features and late results (follow-up: 2-10 years). The group consists of 9 women and 8 men ranging in age from 17 to 80 years (mean of 42.6). 14 patients had a diffuse form, 5 of whom had periportal fibrosis with secondary biliary cirrhosis, which in 3 cases resulted in a portal hypertension with hepatic failure. In only 3 cases the dilatation was limited to the left lobe of the liver. 9 of the patients had previously undergone surgery in the form of cholecystectomy and choledocholithotomy elsewhere. The disease was complicated by lithiasis (14 intrahepatic, 9 extrahepatic). Curative treatment was only possible in the 3 patients with unilobar Caroli's syndrome (partial liver resection). In 5 patients we performed a cholecystectomy and choledocholithotomy combined in 2 cases with a transduodenal sphincterotomy. There was no operative death. Endoscopic treatment consisted in removal of stones and decompression of the biliary tree by sphincterotomy in 9 cases and endoscopic retrograde biliary drainage (endoprosthesis) in 5 cases. Excepting the 3 curative operated patients who are asymptomatic respectively 2, 4 and 5 years after surgery, the remaining cases had repeated bouts of acute pains accompanied by recurrent episodes of cholangitis. A late mortality of 23.5% (4 patients) is proof of the poor prognosis of this disease.

[Surgical therapy of malignant thoracic wall tumors]. / Zur operativen Therapie maligner Brustwandtumoren.

Surgical treatment of primary and secondary malignant chest wall tumors present various difficulties depending on their localisation in the anterior, lateral and posterior thoracic wall. The reconstruction and the flap-plastics have to fulfill the functional and cosmetic demands. We report on 35 patients, 22 female and 13 male, ranging in ages from 19-69 (mean 44.59) years. There were 17 primary and 18 secondary tumors. The operation included excision of the thoracic shield, partial or total breast-bone and clavicle resection. Materials used for reconstruction were PTFE-patches, lyophilized dura and ribs. Soft tissue reconstruction was performed by sliding-flap plastics. The one-year survival rate was 90.6%.

[Pancreas transplantation with exocrine bypass to the gallbladder as receiver. Experimental results and the first clinical case]. / Transplantation pancréatique avec dérivation exocrine dans la vésicule biliaire du receveur. Résultats expérimentaux et premier cas clinique.

A new procedure for intraperitoneal pancreas transplantation, donor-pancreatoduodenectomy/receiver-cholecystectomy, is described. The pancreas, with a segment of the duodenum, is placed dorsally in the peritoneal cavity. The portal vein is anastomosed to the sub-hepatic caval vein and the long aortic segment of the graft is anastomosed with the receiver's aorta. Pancreas exocrine excretion is deviated to the receiver's gallbladder via a duodenobladder bypass.

[Staging and neoadjuvant therapy of squamous cell carcinoma of esophagus]. / Staging und neoadjuvante Therapie des Plattenepithelkarzinoms des Osophagus.

Once the diagnosis of esophageal cancer is established, the decision on treatment will depend on the stage of the disease. Since improvement of prognosis can only be expected in patients with complete removal of their tumor, preoperative staging plays a pivotal role in the decision-making process. Preoperative diagnostic procedures should define the tumor in its relation to the tracheal bifurcation (site), determine the depth of tumor invasion (T status), evaluate regional lymph node metastases (N1 disease) and exclude distant metastases (M1 disease). Endosonography represents currently the most accurate imaging technique for detecting the correct T stage over the correct N stage. A higher accuracy rate may be achieved by combining endosonography with other staging modalities such as computed tomography. Chest x-ray, and percutaneous ultrasonography (abdominal, neck) form the diagnostic basis in staging M1 disease. Computed tomography (neck, chest and abdomen) is currently the best method to detect metastases in the liver and in celiac nodes. Staging laparoscopy when combined with laparoscopic ultrasonography shows a higher sensitivity than ultrasonography and computed tomography in the diagnosis of smaller metastases and peritoneal seedings. En bloc esophagectomy together with the regional lymph nodes remains the treatment of choice in medically fit patients with localized esophageal carcinoma (Stage I-IIB, T1-T2/N0-N1/M0). Due to early involvement of mediastinal structures, curative resection is unlikely to be achieved in patients with locally advanced esophageal carcinoma (Stage III, T3-T4/N0-N1/M0). Most available data indicate that neoadjuvant radiochemotherapy leads in a significant number of patients to downstaging of the tumor, increases the rate of R0 resection, improves local tumor control, and prolongs the recurrence free interval. However, neoadjuvant radiochemotherapy resulted in a marked increase of morbidity and postoperative mortality without improvement of survival. At present, neoadjuvant therapy is still experimental and there is no consensus for an optimal treatment regimen. Its use outside of an investigational setting can not be recommended. Future research must focus on more effective and less toxic neoadjuvant modalities (e.g. new chemotherapy agents, hyperthermia).

[Perception of natural orifice surgery. Results of a survey of female physicians and nursing staff]. / Perzeption der "natural orifice surgery". Ergebnisse einer Umfrage bei weiblichem Ärzte- und Pflegepersonal.

BACKGROUND: Natural orifice surgery (NOS) is now being elaborated with the aim to make abdominal surgery simpler and safer. In order to obtain women's perception of NOS and their willingness to consent to this type of approach a survey was conducted among female employees from surgical disciplines at the University Hospital Charité Berlin. MATERIAL AND METHODS: A written description and information on minimally invasive surgery and the NOS concept were distributed among 500 female physicians and nursing staff along with a 14-item questionnaire. Of the staff members 118 participants completed the questionnaire anonymously. Data analysis was carried out using SPSS 16.0. RESULTS: With regard to ovarectomy 55% of women surveyed indicated that they would prefer a transvaginal approach to standard laparoscopy (44%) or a transgastric approach (1%). When asked about preferred access for cholecystectomy only 31% would prefer the transvaginal method compared to 61% for the laparoscopic technique. Objections against the transvaginal access concerned the impact on a healthy sexual life and effects on fertility. Reasons for choosing NOS were no wound pain and no scar. CONCLUSION: This survey shows that among the surveyed female medical employees the transvaginal approach is associated with concerns and fears but these are not justifiable, as the transvaginal access has been used for more than 100 years for gynecological purposes. There is a strong need for outcome data to enlighten female patients and to help guide physicians when talking to patients regarding NOS and the transvaginal approach.

[Transoral endoscopic thyroidectomy. Part 1: rationale and anatomical studies]. / Transorale endoskopische Thyreoidektomie: Teil 1: Rationale und anatomische Studien.

BACKGROUND: Surgical access trauma in thyroidectomy has been minimized by the adoption of minimally invasive techniques. Extracervical approaches moved the incision lines outside of the visible neck region. However, because of the extensive dissection they no longer comply with the term minimally invasive. Therefore, our goal was to reduce the access trauma and establish a non-traumatic approach according to surgical planes for endoscopic minimally invasive thyroidectomy: the transoral approach. MATERIAL AND METHODS: In a preclinical investigation anatomical dissection was performed on three human cadavers to visualize anatomical relationships and identify safe zones of access to the anterior neck and the submandibular regions. The investigation focused on relevant vascular and neural structures in the floor of mouth. Endoscopic minimally invasive thyroidectomy was additionally performed in five specimens with anatomical dissections for the evaluation of collateral damage. RESULTS: For a safe approach the optic trocar can be placed sublingually in the midline as there are no relevant vascular or neural structures on the way to the thyroid region. The working trocars can be placed bilaterally in the oral vestibule behind the canine teeth. In this way access and dissection plane are placed directly in an avascular subplatysmal area and the pretracheal working space can be reached easily, safe and fast. CONCLUSIONS: Minimum impact and a gentle dissection according to anatomical planes are the rational for the transoral route to the thyroid gland. Thus based on anatomical dissections the foundations of a novel procedure in the context of natural orifice surgery (NOS) could be established.