Anatomic Study Of Endoscopic Transoral-transpharyngeal Approach Treating The Disorder Of Transverse Ligament Of The Atlas.

Objective: To provide anatomical basis for endoscopic transoral-transpharyngeal approach to deal with the transverse ligament of the atlas. To evaluate the feasibility for treating the transverse ligament of the atlas by endoscopic transoral-transpharyngeal approach. To explore the mathodolagy for treating the transverse ligament of the atlas by endoscopic transoral-transpharyngeal approach.Method: 1.The length of the anterior arch of atlas and the interval between the apophysises of the transverse ligament of atlas was measured in 50 atlas specimens. 2.The anatomic data of the transverse ligament of atlas and ajecent fissuses was measured in 20 wet atlanto-axis specimens. 3.The mimic surgical operation on the the transverse ligament of atlas was conducted by classical and endoscopic methods in two groups of cadaveric heads and necks.Results: 1. The length of the anterior arch of atlas was 18.78±2.4mm. 2.The interval between the two apophysises of the transverse ligament of atlas was 17.82±1.9mm. 3. The transverse ligament of the atlas was a structure what likes a backward sarched. The length of the transverse ligament of the atlas was 19.67±2.4mm. The width and thickness of the ends of the transverse ligament of atlas was longer than the width and thickness of the midpoint of the transverse ligament of atlas. The width of the ends of the transverse ligament of atlas was 6.39±1.2mm and 6.49±1.3mm. The thickness of the end of the transverse ligament of atlas was 3.50±0.8mm and 3.6±0.8mm. The width of the midpoint of the transverse ligament of atlas was 10.34±1.8mm. The thickness of the midpoint of the transverse ligament of atlas was 1.96±0.3mm. 4. The thickness of the midpoint of tectorial membrane was 0.93±0.2mm. The thickness of the ends of tectorial membrane was 2.48±0.7mm and 2.52±0.7mm. 5. The minimal distance between the backside of the midpoint of the transverse ligament of atlas and the duramater was 1.7±0.2mm. The minimal distance between the backside of the ends of the transverse ligament of atlas and the duramater was 4.5±0.8mm and 4.5±0.8mm. 6. The minimal distance between the backside of the midpoint of the transverse ligament of atlas and the spinal cord is 4.0±0.5mm. The minimal distance between the backside of the end of the transverse ligament of atlas and the spinal cord was 8.1±1.2mm and 8.0±1.2mm. 7. The minimal distance between the backside of the end of the transverse ligament of atlas and the vertebral artery is 11.8±0.9mm and 11.9±1.0mm. 8. When the odontoid has been exscinded, the maximal moving distance of the midpoint of transverse ligament of atlas in sagittal plane was 5.62±1.3mm. When one ends of the transverse ligament of atlas has been severed, the maximal moving distance was 11.70±1.6mm.Conclusions:1. Endoscopic trans-oral approach to deal with the transverse ligament of atlas is technically feasible, which not only can get the same decompressing size with classical TOA, but also has better exposure, more precise work and less invasion.2. The method of severing the transverse ligament of atlas may be adopted when we deal with the transverse ligament of atlas. The deepness of treating the transverse ligament of atlas can't exceed the "safety deepness".3. When the odontoid has been exscinded, the backside of the transverse ligament of atlas has a "buffer" in existence. It may do some help for estimating that the transverse ligament of atlas must to be severed or not in clinic.