The Anatomical and Clinical Research of Endoscopic Transoral-transpharyngeal Approach to Craniovertebral Junction
|Central South University
|Atlas Atlantoaxial Slope Oropharyngeal Endoscopic surgical techniques Craniocervical junction
Transoral-transpharyngeal approach (TOA) is a classical mothed to treat craniovertebral junction abnormality, which is the most direct approach to the upper cervical spine and clivus. Exposition and traction of the important vasa and nerves could be avoided in this approach. However, there are few detailed anatomical data on craniovertebral junction and structures around them. Moreover, the classical TOA has some shortcomings, including deep operative area, small vision angle and limited exposition. Taken together, application of TOA was limited in the clinical.In past few years, successful experience of the application of MED in lumber spine sheds light on the way to treat eraniovertebral junction abnormality. Because the operative area of TOA is about 10cm deep and 2～3cm wide, just like the working tube of MED. Using light liquid photofibre, convenient and handy operational instruments, and variable micro-drill, we are able to reach deep operation area easily. It makes us trying to combine this mini-invasion technology with classical TOA and exploring the feasibility and safty of this technique.This study consists of two parts including anatomic and clinical research. In the first part, we measured clinical data of atlantoaxis and elivus. Then classical and endoscopic methods to decompress the spinal cord and excise the cartilage surface of the atlantoaxis joint by trans-oral approach are taken separately in two groups of eadaveric head and neck, and we discussed the feasibility of endoscopic trans-oral approach to the upper cervical and clivus. In the second part, 12 patients including secondary basilar invagination caused by migration of odontoid fracture fragments, congenital os odontoideum, congenital basilar invagnition occipitalization, and Klipple-File syndrome were divided into 2 groups. GroupⅠwas operated by endoscopic TOA (ETOA), and groupⅡwas treated by classical TOA. All patients had been followed for at least 1 year. We compared operation time, mouth-opening degree, soft palate splitting, complications, cervical-medullary angle, and JOA score of each group, and demonstrate the feasibility, indications, contraindications, concrete oneration methods of ETOA. Part one: Anatomic Basis and Feasibility of Endoscopic Transoral-transpharyngeal Approach to craniovertebral junctionObjective: To provide anatomical basis for endoscopic transoral-transpharyngeal approach to craniovertebral junction, and evaluate the feasibility of endoscopic trans-oral approach to the upper cervical and clivus.Motheds: 1. The clinical significiant data is observed and measured in the anterior column of 50 dry atlas and axis specimens and 20 skulls. 2. Data of the anterior column of atlantoaxis is measured in 20 X-ray and CT. 3. Five cadaveric heads and necks were anatomized from the pharyngeal mucosa to the dura. We observed the elivus, the atlantoaxis, the vertebral artery, the transverse ligament of atlas, and structures around them. 4. Classical and endoscopic methods to decompresss the spinal cord and excise the cartilage surface of the atlantoaxis joint by transoral approach are separately taken in two groups of cadaveric head and neck with the arteries poured into red emulsion. We discussed methods of endoscopic transoral approach to the craniovertebral junction, and compared decompressing size of the two motheds.Results: 1. The clivus is 28.5±2.2mm long and 19.2±2.3mm wide. The distance between the pharyngeal tubercle and the foramen magnum is 12.4±1.5mm. 2. The anterior arch of atlas has a length of 19.84±2.3mm, with the longest anteriorposterior diameter in the tubercle and the shortest in aside massa. 3. The odontoid is 15.94±1.9mm high. The lagerst transverse diameter of odontoid is 10.54±0.6mm, and it is like a shuttle in shape. 4. The atlantoaxis joint is ellipse shaped, with a transverse diameter of 15.1±1.6mm, and the anteriorposterior size is 17.7±1.3mm. The superior facet horizontal angle of atlantoaxis joint is 23.5±2.8°. 5. The distance between the turbule of atlas and fore-teeth is 9.74±0.4cm. The line from medial edge and lateral edge of atlantoaxia joint to the turbule inclines laterally, with an angle of 4.84±0.3°and 15.2±0.3°. 6. The transverse ligament of atlas is 20. 0±2.40 mm long. The minimal distance between the ligament and the dura is 2.3±0.3 mm, while the maximal distance is 7.1+1.4mm。7. There is not significient difference in measure of X ray and CT and skeletal specimens. 8. There is a safe zone in the front of atlanto-axis of transoral approach, with 45.9±3.6mm wide and 29.4±2.5mm high, and a depth of 10mm. 7. Endoscopic transoral atlantoaxis procedure can get a decompressing size of 45.9±3.6mm wide, 29.4±2.5mm high, and 10mm deep, which has not statistically significant difference between classical and Endoscopic TOA.Conclusions: 1. Endoscopic Vans-oral approach to the the upper cervical and clivus is technically feasible, which allows obtaining the decompressing size same as classical TOA. This technique has better exposure, more precise work and less invasion as well. 2. We can either drill the arch from the tubercle to the lateraiside or break the arch from where it connects to the aside massa. Endoscopic odontoid dissection should begin at the apex of the odontoid and proceed inferiorly. We should drill the cartilage of the atlantoaxis joint inside the articular capsule. The width and depth of cartilage dissection should be limitied in 12mm and 10mm in order to avoid damage to vertebral artery and spinal cord. 3. The safe zone of TOA operation may do some help to diminish clinical complications. underwent the operation of endoscopic transoral approach to decompress their anterior cevicomedullary compressive abnormalities. During the operation, we dissected the anterior arch of atlas to expose the odontoid, but in case of severe basilar invagnition, part of the clivus was removed. We drill the odontoid from the apex to. the base in basilar concave, and from the base to the apex in odontoid fracture and os odontoideum. Then the cartilage of atlantoaxial lateral joint were removed. In groupⅡ, there were 3 males and 2 females, aged from 22 to 38 years old with a mean of 30 years. The abnormalties in this group were 3 cases of congenital basilar concave and 2 cases of occipitalization. All the cases were operated by classical TOA with anterior arch of atlas and odontoid resection. Complications and JOA score and Cervical-medullary angle were compared in 2 groups.Results: All patients were operated successfully. Patients in group I can be operated in a condition of poor mouth-opening degree, while patients in groupⅡmust require their monthes opened more than 4cm wide to allow the operation to be done. It is not necessary to splite soft palate or hard palate in the groupⅠ, and there was no temporomandibular joint pain left in this group. In the groupⅡ, the soft palate were splited in 3 patients, and all patients in this group left various degrees of temporomandibular joint pain. There were no cerebral spinal fluid leakage, infection, injure of spinal cord and veterbral artery in both groups. However, there was one patient from each group being reoperated to fuse the atlas and axis in 3 months after the first operation. All patients were followed up from 12 to 18 months (15 month at the average). The cervical-medullary angle was increased from 101.5°to 121.7°in groupⅠand from 101.2°to 123.7°in groupⅡ. JOA scores in 2 groups were increased after operation, but the difference between them was not statistically significant.Conclusions: 1、Endoscopic transoral surgery represents a new microsurgical technique to treat the craniovertebral abnormalities, which provids better expose and more precise work, and could achieve satisfactory outcomes. 2、There is still some problems with the endoscopic system in atlantoaxis procedure needing to be solved in the future.