Applied Anatomy Of Endoscopic Transoral Resection Of Odontoid

Transoral approach for curing the ventral lesions in cranio-vertebral junction isrecognized as a classic approach, which can direct access to the belly line incranio-vertebral junction and avoid pulling important anatomic structure, but thisapproach is depressed at the present stage due to its disadvantages such as serioustrauma, limited depth of field and many postoperative complications. The appearanceand application of neuroendoscopy is a good solution to the problems existing in themicroscope.The anterior approach operation made by Kanavel in early1917removed theshrapnel in anterior arch of the atlas. Fang reported transoral approach articulationatlantoepistrophica joint fusion in1962and then this approach is graduallyrecognized by people. But the approach gets slow development due to the risk ofinfection and overestimation about the difficulty of approach operation. Since1998,the operation has been developed in the domestic several large hospitals, seldom inlocal hospitals. There are three main reasons. The first one is the lack ofmorphological data. The current study of atlantoaxial mainly concentrates on the bonestructure and biomechanics, with few reports about atlantoaxial and adjacentstructures, especially the spinal cord, nerve, vessel detailed anatomy. Secondly, thetraditional transoral operation has its own deficiency. The operation must be throughthe mouth, with deep surgical field, small viewing angle, limited exposure and the operating depth is difficult to master. And because of poor visibility, deep anatomicalposition, the operation is easy to cause the patients with injury in dura mater,vertebral artery and even spinal cord in the largest mouth-open for a long time, andcan cause the trauma and dislocation of temporomandibular joint and the majority ofpatients will suffer pain of temporomandibular joint after operation. Thirdly, thetraditional transoral operation has no special lighting system and operating equipment,which seriously hampers its clinical application.In recent years, the application of neuroendoscopy in the clinic makes up for thedeficiency of operation under the microscope. This thesis aims at applying cadaverichead and relevant specimen to observe and measure the anatomic landmark ofrelevant area such as transoral approach cranio-vertebral junction so as to getanatomic data; simulate transoral resection of odontoid under neuroendoscopy andmicroscope and study the application value of neuroendoscopy in transoral resectionof odontoid. This thesis is divided into two parts. PART ONEApplied anatomy of endoscopic transoral resection ofodontoid under the neuroendoscopyObjectiveApply neuroendoscopy to simulate transoral resection of odontoid in cadaverichead specimen and observe the anatomic characteristics in cranio-vertebral junctionand the application value of neuroendoscopy in the operation.MethodUse the neuroendoscopy with0°and30°to simulate transoral resection ofodontoid on the10corpse head specimens of adult in Han nationality fixed byformaldehyde and make anatomy study on the veutro of cranio-vertebral junction anddiscuss the feasibility of reserving part of atlas anterior tubercle resection of odontoidunder the control of endoscope.ResultCadaveric head simulation operation does not make the soft palate incisionexposure. Choose F12single lumen catheter to enter from bilateral nasal cavity andmake transfixion with the root of soft palate. Outside the nasal cavity, appropriatelypull and overhang catheter to fully expose the paries posterior of pharynx. Thelongitudinal observable range under endoscope with00:1/3below the slope tosuperior border of C2; longitudinal observable range under endoscope with300:middle part of slope to inferior margin of C2. Under the control of endoscope,9casesare successively removed from1/2below the atlas anterior tubercle and the basilarpart of odontoid process and finish calyptriform removal of top of odontoid process,the remaining one case fails to make experimental operation of endoscope because ofabnormal mouth of specimens.Conclusion1. Resection of odontoid process under the control of endoscope is moreminimally invasive, with wide surgical field, can actively protect the safety ofimportant anatomic structure in veutro of cranio-vertebral junction. 2. Retain part of free resection of odontoid process in anterior tubercle of atlasthat is more minimally invasive under endoscopic control. PART TWOApplied anatomy of transoral approach of microscopeObjectiveBy observation, anatomy and measurement of bone specimen and sectionpreparation, apply microscope to simulate transoral resection of odontoid in corpsehead specimen and establish the margin of exposure and operation safety zone oftransoral approach under microscope.MethodObserve36dry skull base,5sets of atlantoaxial specimens, get the required dataand anatomical landmarks, use operation microscope to simulate transoral resectionof odontoid on the10cadaveric head specimens of adult in Han nationality fixed byformaldehyde and make anatomy study on the veutro of cranio-vertebral junction.ResultThe measured longitudinal slope outside diameter is28.9±3.5mm; The slopeoutside diameter is18.3±3.3mm; interval from pharyngeal tubercle to the anteriormargin of occipito-foramen is12.6±2.4mm; the interval of bilateral occipitalcondyle edge is19.2±3.5mm; interval of bilateral hypoglossal canal outside mouthedge is33.7±2.5mm; interval of bilateral carotid canal outside mouth edge is44.6±4.5mm; interval of bilateral jugular foramen outside mouth edge is38.3±3.2mm;interval of bilateral rupture hole edge is20.5±3.3mm. The measured anteriortubercle of atlas is9.8±0.7mm high,8.1±0.6mm thick; odontoid height is13.1±2.7mm, with thickness for14.2±2.4mm thick.The interval of C1level of vertebralartery edge is45.3±2.9mm; interval of C2level of vertebral artery edge is38.9±1.8mm; interval of C3level of vertebral artery edge is37.4±1.9mm. The standardtransoral longitudinal observable range:1/3below the slope to superior border of C2;the longitudinal observable range after incision of soft palate: middle part of slope toinferior margin of C2. Conclusion1. Transoral approach can directly reach the center line of veutro in thecranio-vertebral junction and expose the odontoid.2. Safety zone of cranio-vertebral ventral operation defines the longitudinaldistance from the leading edge of foramen magnum to the basilar part of axis and thetransverse distance is in the deformation of vertebral artery on both sides. The area isnarrow inverted trapezoidal.3. It can expand the vision of operation to the middle part of the slope afterincision of soft palate.