| Objective:To explore the significance of flexion and extension imaging examination in the diagnosis of atlantoaxial dislocation and in guiding the formulation of surgical strategies.Materials and Methods:The role of imaging examination in neutral position and flexion and extension position in the diagnosis of atlantoaxial dislocation and in guiding surgical strategy formulation was analyzed by prospective study.Firstly,the inclusion conditions of the research objectives were determined: all patients with clinical symptoms,signs,and routine neutral imaging examination suggesting that there may be instability of craniocervical junction.In order to avoid causing or aggravating spinal cord injury,unstable craniocervical junction caused by obvious trauma history was excluded,especially in patients with cervical vertebral fracture.From January 2017 to October 2018,40 patients who met the inclusion criteria were selected from neurosurgery patients in Guizhou Provincial People's Hospital.Among them,17 were males,and 23 were females,ranging in age from 7 to 68 years,with an average age of(41.93±15.86)years.Neutral and flexion and extension X-ray,CT,and MRI were performed after adaptation assessment.The criteria for diagnosis of atlantoaxial dislocation are: In neutral position,when the space between the posterior edge of the anterior arch of the Atlanto-dental interval(ADI)is greater than 3 mm in adults and 5 mm in children,atlantoaxial dislocation is diagnosed.In flexion and extension position,atlantoaxial dislocation was diagnosed as atlantoaxial dislocation with the difference of atlanto-dental distance > 2 mm.The ADI values of X-ray,CT,and MRI in neutral position and flexion-extension position were measured,and the difference of ADI changes in flexion-extension position was calculated.According to the diagnostic criteria,the number of atlantoaxial dislocations diagnosed by imaging examinations in neutral and flexion-extension positions was counted,especially those who were not clearly diagnosed in conventional neutral position but were diagnosed by flexion-extension imaging,and Chiari malformation with syringomyelia,basilar invagination,assimilation of atlas,Atlantoaxial lateral subluxation,Klippel-Feil syndrome and other malformations of the craniocervical junction which may lead to craniocervical instability were counted.The roles of X-ray,CT,and MRI in the diagnosis of atlantoaxial dislocation in neutral position and flexion-extension position were comprehensively compared and analyzed.Individualized surgical treatment was formulated according to the guidance of flexion-extension imaging.For reducible dislocation,direct posterior bone grafting and internal fixation is recommended.For irreducible dislocation,posterior bone grafting and internal fixation are performed under continuous traction.For irreducible dislocation,posterior reduction and fixation are not recommended,and anterior odontoid process resection is performed directly.SPSS22.0 statistical software was used for statistical analysis.The diagnostic rates of atlantoaxial dislocation in X-ray,CT,and MRI neutral position and flexion-extension position were analyzed by McNemar's test.The difference was statistically significant(p < 0.05).Results:(1)In 40 patients,25 cases of atlantoaxial dislocation,26 cases of Chiari malformation with syringomyelia,33 cases of basilar invagination,26 cases of assimilation of atlas,19 cases of Atlantoaxial lateral subluxation(including 1 case of type N,9 cases of type I,4 cases of type III,1 case of type IV),17 cases of Klippel-Feil syndrome and 32 cases of spinal canal stenosis(7 cases of grade 0,1 case of grade 1,0 cases of grade 2 and 32 cases of grade 3)were diagnosed by routine neutral and dynamic X-ray,CT and MRI examinations.Twenty-five cases of atlantoaxial dislocation with Chiari malformation and syringomyelia accounted for 68.00%,20 cases with basilar invagination accounted for 80.00%,17 cases with the assimilation of atlas accounted for 68.00%,14 cases with Atlantoaxial lateral subluxation accounted for 56.00%,and 12 cases with Klippel-Feil syndrome accounted for 48.00%.Also,flexion and extension imaging revealed 3 cases of basilar invagination(considering vertical dislocation),including 2 cases with lateral atlantoaxial joint slippage and 1 case with only vertical dislocation.(2)25 cases of atlantoaxial dislocation,of which:There were 9 cases with ADI > 3 mm in X-ray neutral position,17 cases with ADI change difference > 2 mm in flexion and extension position.By paired chi-square test,the chi-square value was 6.125,the p-value was 0.008,p < 0.05.At the level of ?=0.05,the difference was statistically significant.There were 14 cases with ADI > 3 mm in CT neutral position,25 cases with ADI change difference > 2 mm in flexion and extension position.By paired chi-square test,the chi-square value was 9.091,the p-value was 0.001,p < 0.05.At the level of ?= 0.05,the difference was statistically significant.There were 13 cases with ADI > 3 mm in neutral position,23 cases with ADI difference > 2 mm in flexion and extension position.By paired chi-square test,the chi-square value was 8.100,the p-value was 0.002,p < 0.05.At the level of ?= 0.05,the difference was statistically significant.The number of cases of atlantoaxial dislocation diagnosed by X-ray and CT flexion and extension imaging examination was checked by paired chi-square test.The results showed that the chi-square value was 6.125,the p-value was 0.008,p < 0.05.At the level of ?=0.05,the difference was statistically significant.The number of cases of atlantoaxial dislocation diagnosed by X-ray and MRI flexion and extension imaging examination was checked by paired chi-square test.The results showed that the chi-square value was 4.167,the p-value was 0.031,p < 0.05.At the level of ?=0.05,the difference was statistically significant.The number of cases of atlantoaxial dislocation diagnosed by MRI and CT flexion and extension imaging examination was matched by chi-square test.The results showed that the chi-square value was 0.500,the p-value was 0.500,p > 0.05.There was no significant difference at the level of ?=0.05.(3)In this study,28 patients with atlantoaxial dislocation or instability were definitely diagnosed by flexion and extension imaging.Twenty-six patients underwent posterior bone grafting and internal fixation,including 22 patients with atlantoaxial dislocation,three patients without atlantoaxial dislocation but with basilar invagination(vertical dislocation)and Atlantoaxial lateral subluxation,and one patient with atlantoaxial left mass arthritis degeneration leading to atlantoaxial joint degeneration.In 7 patients with simple Chiari malformation and syringomyelia,flexion and extension imaging showed that there was no instability at the craniocervical junction,so posterior fossa decompression,lower hernia,cerebellar tonsillectomy,and occipital cistern reconstruction were performed;7 patients did not undergo surgical treatment.Conclusion:(1)Conventional neutral imaging examination misses the diagnosis in the diagnosis of atlantoaxial dislocation.Flexion and extension imaging examination makes up for the deficiency of neutral imaging examination and improves the diagnostic rate of atlantoaxial dislocation or instability,especially flexion and extension CT,which can be used as an important supplementary means of conventional neutral imaging examination.(2)Imaging examination in flexion and extension position can dynamically reflect the stability of the atlantoaxial joint,and MRI examination can dynamically reflect the compression of the spinal cord,which provides an objective and accurate basis for preliminary judgment of the reversibility of atlantoaxial dislocation and guidance for the formulation of appropriate individualized surgical treatment.(3)It has certain diagnostic value for vertical dislocation and lateral atlantoaxial joint slippage. |
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