Applied Anatomy Of The Endoscopic Endonasal Approach To The Ventral Cranio-cervical Junction

Craniocervical junction is a complex anatomical structure,Gladstone and Erickson-Powell first described this region in 1815,which includes inferior one-third of clivus,atlas,atlantoaxial and foramen magnum,as well as the important neurovascular structures in the region.Because the region is located adjacent to the skull base,deep brain stem,upper cervical cord and other vital structures,anatomical relationship are so complex that it is difficult to have an operation.Although the traditional treatments of surgical lesions in the region can relieve the lesions on the craniocervical junction at different levels and ease the oppression,but these methods often cause damage to a large extent of bone tissue and treatment of traction of neurovascular.Traumas are too large and have the existence of serious complications. As far as the ventral craniocervical junction lesions are concerned,Kanavel firstly proposed the transoral approach in 1917,which uses the body's natural physiological Lacunar,and no essential blood vessels nerves exist in front of craniocervical junction,the approach can directly expose cranio-cervical junction ventral midline lesions from the inferior one-third of clivus to the C₂ vertebral body.Even a considerable number of scholars believe that such a surgical approach is the optimal solution to the lesions of ventral craniocervical.junction.But the traditional transoral approach also have a larger wound because it requires incision of hard palate and soft palate,damaging the teeth and temporomandibular joint,causing tongue edema ischemia even necrosis.In recent years,with economic development,social progress and people's living standards improvement,people required surgeons removed their lesions completely, at the same time,also called for as much as possible to reduce the surgical invasion and improve postoperative quality of life.Traditional surgical methods have been replaced by minimally invasive surgery gradually,because of their large trauma,the high incidence of complications,great surgical risks,a long recovery period,patients suffering big disadvantage,and higher medical costs.Since Steven Gans and Bradley Rodgers first diagnosed the disease for infants and children by using laparoscopy and thoracoscopy,minimally invasive surgical techniques has been developed rapidly.Simultaneously with the development of optical fiber,medical laser,micro-electronics,as well as the new biological materials, the minimally invasive surgery which were represented by using a variety of endoscopic have been emerging.In the early 1970s,Messerklinger firstly carried out endoscopic sinus surgery which is known as "Messerklinger technology" has become the cornerstone of surgery endoscopic sinus surgery technology,and it was widely used and expanded endlessly.Alfieri extended the surgical technique to the ventral craniocervical junction area in 2002 and put forward the opinion that treating the craniocervical junction lesions by using the endoscopy.In 2005,Kassam depended on the basic researches which were studied by Alfieri and others,firstly carried out the surgical technique in clinical practice,and achieved the desired results. Compared with transoral approach,the endoscopic endonasal approach to the ventral cranio-cervical junction although has many advantages,but the surgical approach path is longer,relatively narrow space operation,distorted images,two-dimensional image which lack of three-dimensional sense,coupled with the surgical approach to this region adjacenting to important and complex anatomical structure.On the one hand,surgeon should have excellent basic skills of endoscopic sinus surgery,on the other hand,also be familiar with the nasal cavity and paranasal sinuses and nasal skull of the anatomical landmarks.The purpose of this task is through observational study the features of the endoscopic endonasal approach to the ventral region of cranio-cervical junction to establish the structures which is relatively constant at the same time easy to observe as the surgical marking points,and carry out a detailed description of the structures which surround the adjacent of surgical approach.At the same time,we measure the relevant anatomical structures around the important observation measurements,to establish the relative safety range of the operation.And on this basis,using the corpse's head to follow the actual process of clinical,simulate to the ventral craniocervical junction surgery,pre-validation studies established the usefulness of surgical marking points,and further proves that the the feasibility and safety of the operation.Our research includes three parts as following:Chapter.1 The establishment of the surgical landmarks of the endoscopic endonasal approach to the ventral cranio-cervical junctionObjective:Through the anatomy study of the endoscopic endonasal approach to the ventral cranio-cervical junction,provide anatomical basis,find the structures which are relatively constant as well as easy to observe,and establish these structures as surgical marking points.At the same time,we describe its surrounding neighbors with a view to expediting this surgical method in clinical application.Methods:Twenty 10%formalin-fixed intact adult head-neck specimens were used to dissect and observe the anatomic features of this access in order to establish the surgical landmarks of the approach.Following the surgery approach,incised along the median sagittal line of head and neck specimens,in order to observe the the anatomic features of the approach,look for some of the relatively constant and easy to observe the anatomical structures,establish these structures as signs of the operation points,and make the use of instrument to make the anatomical observation of the anatomical landmark points on the around adjacent to the relationship.Results:Using twenty 10%formalin-fixed intact adult head-neck specimens observe the anatomic features of this access in order to establish the surgical landmarks of the approach,includ:middle turbinate,choana narium,Eustachian tube ostium,nasopharynx mucosa,longus capitis and longus colli,basion,tuberculum anterius atlantis.Make the anatomical observation of the anatomical landmark points on the around adjacent to the relationship.When operating the structures within the surgical field can be confirmed by identifying the anatomical location of structures around these points in order to complete resection of lesions,and also to reduce complications.Conclusion:In this study,we select constant and easy to confirm anatomical structures as surgical landmarks for the endoscopic endonasal approach to the ventral region of cranio-cervical junction,the structures around these points were described in detail.Intraoperative identification of these points as the basis,and to master the structures of these marking points around the adjacent relations can be targeted,that is,to achieve the purpose of effective disarmament lesions,and also essential to avoid injury in the structure,reduce or even avoid complications.Chapter.2 Applied anatomy of the endoscopic endonasal approach to the ventral cranio-cervical junctionObjective:Through the anatomical study,measurement the distance from the dependency structures to the median line,with a view to the entry road to provide anatomical basis and to establish the safe range of the operation.Methods:Twenty 10%formalin-fixed intact adult head-neck specimens were used,Along the midline sagittal incise corpse head to choanal and from the side of the mid-point of zygomatic arch inward cut coronal and sagittal tangent to the intersection,and separate the of two parts.An accuracy of 0.01 using the vernier caliper and compasses,measurement of the surgical approach important anatomical structure:â‘ the distance from pterygoid canal,pharyngeal opening of eustachian tube,foramen lacerum,External entrance of the hypoglossal canal,Internal carotid artery at atlas or axis,Canalis caroticus,Vertebral artery at inferior border of axis, Vertebral artery at superior border of axis,Vertebral artery at inferior border of atlas, Vertebral artery at superior border of atlas,Anterior border of occipital condyle to the medial midline;â‘¡anterior nasal spine away from the pharyngeal tubercle, leading-edge midpoint of foramen magnum,anterior tubercle of atlas distance.And apply software spss 13.0 statistical data for measuring statistical treatment,the results of using(?)±s express,and the right and left data matching t test,P＜0.05 for significant difference.Results:The endoscopic endonasal approach to the ventral cranio-cervical junction completely exposed craniocervical junction,the shortest distance(89.75±2.80) mm;The anterior-inferior wall of sphenoid grinding to both sides of the pterygoid canal in addition to the scope of control for the sector,for the distance is midline(9.37±0.59) mm;under grinding in addition to the scope of the clivus to both sides of foramen lacerum for the sector,as from the midline(10.75±0.63) mm;At the atlantoaxial segment,vertebral artery at inferior border of axis of the shortest distance from the midline for(15.70±2.12) mm;left atlantoaxial department carotid artery is greater than the right distance from the midline (t=3.453,P=0.003),other targets of the right and left sides was no significant difference(P＞0.05).To reduce the postoperative cerebrospinal fluid leakage,set up the "U"-type flap,the lateral boundary should be for both sides of the pharyngeal opening of eustachian tube,away from the midline of about(10.82±0.92) mm.Conclusion:The endoscopic endonasal approach to the ventral cranio-cervical junction is the same as any other kind operation,there are certain indications for surgery.This approach will get better therapeutic effect when the lesions which located at the ventral craniocervical junction area near the midline,and while there is a larger deviation when the lesions from the midline of the risks.The approach can exposure the ventral craniocervical junction region safely and adequately by making full use of the surgical landmarks,and operating within important structures related to the lateral sector.Chapter.3 Endoscopic anatomy of the endoscopic endonasal approach to the ventral cranio-cervical junctionObjective:On the base of established the surgical landmarks and relatively safe operating range,simulate the approach following the actual operation of the clinical process on the specimens,validate the usefulness of surgical marking points have been established,and further prove the feasibility of the operation and safety.Methods:Using a diameter of 4mm,length 18cm of 0°nasal endoscope and the parts of endoscopic devices,five fresh and intact head-neck specimens injected with colored latex were used and completely simulant operation via endoscopic endonasal approach to the cranio-vertebral junction following the clinical course of the actual operation was performed in all cases.Results:Following the clinical course of the actual operation and making use of pre-established surgical landmarks,we can expose the ventral craniocervical junction area safely and fully.Craniofacial incision,bone and muscle injuries,brain tissue,as well as pull off the important nerves and blood vessels can be avoided.At the same time,compared with transoral approach:1.Get craniocervical junction more directly;2.without cutting the soft palate and hard palate can get all the clivus and craniocervical junction,even a broader regional areas;3.Endoscopic operation of a broader vision,a clearer surgical field;4.from the superior anterior arch of atlas and odontoid tip fate level slightly above the pre-show,there is probably only the tip part of odontoid resection,and the retention of some of the former arch of atlas or even atlantal not removed anterior arch,reducing the craniocervical junction stability.5.To avoid damage teeth,temporomandibular joints and tongue injury.Conclusion:In this study,on the base of established the surgical landmarks and relatively safe operating range,through simulate operation on the fresh corpse, confirmed the practicality of landmarks which were established prophase,and confirmed making use of established surgical marking point intraoperatively,and strictly controlling operation at the medial important surgery-related structures,can be fully exposed and deal with the ventral craniocervical junction epidural compressive lesion,and also can be revealed subdural structures,at the same time can avoid injury in the surrounding vital structures,thus avoiding serious complications.Further confirmed applying the endoscopic endonasal approach to the ventral cranio-cervical junction is feasible and safe.