Classification Of Basilar Invagination And Its Significance Influence On Operation Strategy

Objective: To propose a classification system of basilar Invagination based on pathogenesis and to investigate its clinical significance. Methods: From July 2004 to Marth 2010 , 18 patients with basilar Invagination were treated in our hospital.It included 8 males and 10 females with a mean age of 35.7 years (ranged 13-56 years) . Chamberlain line?McRae line?Wackenheim line?atlantodental interval?Klaus height index and Cervicomedullary angle were measured in all the patients, and divided into two groups according to pathogenesis: A group, there were 9 cases treated by transoral surgery followed occipitocervical or atlantoaxial fixation and fusion. B group, there were 9 cases treated by craniovertebral junction decompression surgery followed occipitocervical fixation and fusion. The preoperative average JOA scale score of A group was 11 point (ranged 2-17 years) , the preoperative average JOA scale score of B group was 13.8 point (ranged 12-17 years) .All the data were analyzed with SPSS 17.0. Results: 15 patients were followed up from 1 year to 6 years with an average of 35 months. In A group, the postoperative average JOA scale score was 13.5 point.The outcome of surgical treatment showed excellent 2 in cases, good in 2 cases, fair in 2 cases and poor in 0 case.The excellent and good rate was 67.7%. In B group, the postoperative average JOA scale score was 15.9 point .The outcome of surgical treatment showed excellent 7 in cases, good in 0 cases, fair in 1 cases and poor in 1 case.The excellent and good rate was 77.8%. Dead in 3 cases, complication including internal fixation loose in 1 cases, cerebral spinal fluid leakage in 1 cases, meningitis in 1 cases, pharyngeal wound dehiscence in 1 cases. McRae line?Wackenheim line and atlantodental interval had significant difference in two groups (P<0.05) , and group A is larger than group B?But in Chamberlain line?Klaus height index and Cervicomedullary angle, no significant difference was observed (P>0.05) . Conclusion: If basilar Invagination has a fixed atlantoaxial dislocation, and the tip of the odontoid process was above McRae line and Wackenheim clival line, transoral surgery followed by occipitocervical or atlantoaxial fixation was the most suitable. If basilar Invagination has no atlantoaxial dislocation, and the tip of the odontoid process was superior to McRae line and Wackenheim clival line, craniovertebral junction decom- pression followed by occipitocervical fixation was found to be appropriate.