Anatomical Study And Clinical Application Of Endoscope-assisted Trans-oral Approach For Resection Of Parapharyngeal Space Tumors

Part Ⅰ Anatomical Study of Endoscope-assisted Transoral Approach and Transcervical Approach to the Parapharyngeal SpaceObjectiveTo observe the range and anatomical landmarks of landmarks of anatomical exposure between endoscope-assisted transoral approach and transcervical approach to the parapharyngeal space,To improve the understanding of the anatomical structure of the parapharyngeal space,to provide anatomical basis for clinical selection of surgical approaches and improvement of the success rate of surgery.MethodTwo cases(4 sides)of fresh adult cadaverous head and neck with intact skull bone,smooth maxillofacial skin and oropharyngeal mucosa,and no anatomical study were selected.The specimens were fixed in a self-made head fixation frame according to different approaches,The parapharyngeal space was dissected layer by layer by simulated endoscope-assisted transoral approach and transcervical approach.Result1.Endoscope-assisted transoral approach:After tonsillectomy,it was extend up to the hard palate along the tonsil fossa,separate the palatine muscles,exposed the pterygoid process,exposed the suprapharyngeal constrictor muscle,and remove part of the suprapharyngeal constrictor muscle into the pre-styloid space,where adipose connective tissue can be seen and touch the styloid process.In order to increase the opening degree,the pterygoid muscle can be cut off.To remove the structure of the pre-styloid space,to expose the styloid process diaphragm and the styloid pharyngeal muscle and the styloglossus muscle in front,and to continue to dissect the posterior styloid space,glossopharyngeal nerve,external carotid artery,pterygoid venous plexus,ascending pharyngeal artery,internal carotid artery,vagus nerve,internal jugular vein,hypoglossal nerve,accessory nerve,stylohyoid muscle,posterior abdomen of digastric muscle,lower border of parotid gland,the main stem of facial nerve and sternocleidomastoid muscle can be exposed.The suprapharyngeal constrictor muscle is a sign of entering the pre-styloid space,and the stylopharyngeal muscle and the styloglossus muscle are the safe front boundaries for entering the posterior styloid space.2.Transcervical approach to the parapharyngeal space:Make an arc-shaped incision through the front of the mastoid process and the posterior ascending ramus of the mandible,around posterior mandibular angle to the level of the great angle of the hyoid bone,and then cut the skin,subcutaneous tissue,and musculns platysnma to expose the lower margin of the parotid gland and the upper margin of the sternocleidomastoid muscle.Lift up the lower part of parotid gland,free sternocleidomastoid muscle anterior edge to mastoid tip,free and dissected upward along the posterior abdomen of the digastric muscle,close to the the digastric muscle groove,under the external auditory canal cartilage behind the root of the styloid process,and expose the main facial nerve.After cutting off the posterior abdomen of the digastric muscle and the stylohyoid muscle,the contents of the posterior styloid space can be revealed:hypoglossal nerve,external carotid artery,styloid pharyngeal muscle,styloglossus,glossopharyngeal nerve,internal jugular vein,vagus nerve,Internal carotid artery and accessory nerve.Among them,the posterior abdomen of the digastric muscle and the stylohyoid muscle are important anatomical landmarks to enter posterior styloid space,and the first cervical transverse process is an important bony landmark for finding accessory nerves.Conclusion1.There are some differences in the anatomical range,the order of exposure of important structures and the anatomical landmarks between endoscopic approach and cervical approach.2.Familiar with the internal anatomical structure of the parapharyngeal space,gradual separation in strict accordance with the anatomical level,and identification of important anatomical landmarks during the operation will helpfui to improve the success rate of surgery.Part Ⅱ Clinical Application of Endoscope-assisted Transoral Approach for Resection of Parapharyngeal Space TumorsObjectiveTo evaluate the therapeutic effect of endoscope-assisted transoral resection of parapharyngeal space tumors,and to provide reference for the rational use of the operation in clinical practice.MethodThe clinical data of 34 patients with parapharyngeal space tumors admitted to the Department of Otorhinolaryngology Head and Neck Surgery,the First Affiliated Hospital of Zhengzhou University from January 2013 to October 2020 were retrospectively analyzed.All patients underwent the surgery of endoscopic transoral approach resection of parapharyngeal space tumors age,sex,clinical manifestation,location of onset,pathological type,intraoperative blood loss,operative time,postoperative days of hospitalization,postoperative complications and recurrence,and follow-up were collected.ResultAmong the 34 patients,20 were males and 14 were females;Preoperative CT or MRI examination was performed in all patients,indicating that the parapharyngeal space tumors,31 cases were located on the medial or anteromedial side of the internal carotid artery,3 cases were located on the lateral or anterolateral side of the internal carotid artery,The maximum tumor diameter was 2.7cm-7.8cm.Thirty-three patients were completely resected through the endoscopic-assisted transoral approach,and one patient was completely resected through transoral approach in 2 times due to intraoperative bleeding.Postoperative pathological results showed 33 cases of benign tumors and 1 case of malignant tumors.One patient with mucoepidermoid carcinoma was given radiotherapy 20 days after surgery.The clinical symptoms of most patients were relieved after surgical treatment.Among them,the left vocal cord fixation failed to improve in 1 patient,and the deflection of tongue extension in 2 patients was relieved slightly after surgical treatment.Transient Horner syndrome occurred in 1 case,wound dehiscence occurred in 2 cases,and maxillofacial swelling and difficulty in opening the mouth occurred in 1 case.The follow-up time was 4-88 months,with a median follow-up time of 24 months.One patient with mucoepidermoid carcinoma was in stable condition.No evidence of recurrence of imaging and clinical symptoms was found in 33 patients with benign tumors.Conclusion1.Endoscopic-assisted transoral approach provides a good condition for the resection of parapharyngeal space tumors,which can clearly identify the tumors and the surrounding important tissue structures.2.Endoscopic-assisted transoral approach for resection of parapharyngeal space tumors without facial scar,less complications,low recurrence rate,has a good application prospect.3.Endoscopic-assisted transoral approach is suitable for parapharyngeal space tumors located in the medial or anteromedial side of the internal carotid artery.This procedure can also be used for some tumors located outside the internal carotid artery without vascular invasion and a few malignant tumors with complete capsule.