| Chapter 1:An investigation on sagittal sequence morphology of craniocervical in patients with sleep apnea after occipitocervical fusion(OCF)Background:Atlantoaxial dislocation(A AD)is an anatomical abnormality of atlantoaxial joint caused by trauma,degeneration,tumor,congenital malformation,pharyngitis,surgery and other factors.Many AAD patients have obstructive sleep apnea hypopnea syndrome(OSAHS).If not handled properly,this situation may endanger their daily life and even threaten their survival.Whether preoperative or postoperative,there are OSAHS-related risks.Occipitocervical fusion(OCF)is the main treatment for AAD by providing immediate joint fusion.However,OCF may cause or aggravate OSAHS and even dyspnea.Some studies assumed that this is related to the morphological changes of cervical sagittal plane sequence such as straightening of cervical curvature,increasing distance of cervical vertical sagittal line,and even kyphosis deformity after fusion.In recent years,cervical sagittal sequence parameters have increasingly attracted the attentions in the field of spinal surgery.Researchers have gradually realized the impact of cervical sagittal sequence morphology on physiological functions such as respiration and sleep,and evaluated its predictive effect.It has gradually become an important parameter in making operation plan and a reference index for observing the curative effect of operation.Based on OSAHS patients after OCF,this study intends to evaluate the O-C2a,CVT/NSLA and other indexes on lateral cervical films,including the head,and to explore the correlation between the morphological parameters of different cervical sagittal plane sequences and the changes of oropharyngeal airway,in order to provide reference data for reducing the complications in upper cervical surgery.Method:From January 2018 to December 2021,this study performed posterior OCF in the spine surgery of China Japan Friendship Hospital,and selected the patients who completed the last follow-up as required.The data required in the study were obtained from the OA electronic case system of our hospital and the outpatient case system during follow-up.All patients were fully informed of the purpose of the study and relevant rights and obligations by the investigator before enrollment,and obtained the informed consent of the patients.AAD patients were screened with STOP-Bang questionnaire before and 1 week after operation.According to whether the SBQ score two weeks after operation was higher than that before operation,if it was higher,it was divided into"airway obstruction improvement group";Otherwise,the patient was classified as"airway obstruction exacerbation group".The difference between preoperative and postoperative scores was recorded as Δ SBQ.The morphological parameters of sagittal plane sequence of skull and neck,including O-C2a,McGregor line and CVT/NSLA,were measured on preoperative and postoperative lateral plain films of cervical spine,including skull.In order to study the correlation between CVT/NSLA,O-C2a changes and SBQ caused by OCF,Δ CVT/NSLA and Δ O-C2a is calculated as follows:ΔCVT/NSLA=postoperative CVT/NSLA-preoperative CVT/NSLA and Δ O-C2a=postoperative O-C2a-preoperative O-C2a.In this study,the changes of OSAHS were indirectly reflected by Δ SBQ.Results:A total of 25 eligible patients were included in the study and received OCF.There were 14 male patients,accounting for 56.0%of the total sample,and 11 female patients,accounting for 44.0%.The average age was 62.5±19.5 years old,and the average body mass index(BMI)was 22.3±3.4kg/m2.Among the 25 patients,22(88.0%)were improved and their symptoms were significantly improved.Fusion ranged from occipital to C2 in 20 patients(80%).The remaining 5 patients(20%)were fused to C3-C6 due to incomplete posterior structure of C2.There were no complications such as loosening,failure,postoperative neurological damage and infection of internal fixation.The SBQ score of 25 patients was 5.5 ± 2.1 before operation and 4.2 ± 2.0 after operation.Among them,there were 2 patients whose total score≥ 3,that is,patients with moderate and severe OSAHS.The average follow-up time was 15.2±10.7 months.There were no complications such as loosening,failure,postoperative neurological damage and infection of internal fixation.The postoperative O-C2a value was higher than the preoperative O-C2a value,which was statistically significant(22.5 ± 4.6 vs 16.5 ± 3.8,P<0.001);The postoperative CVT/NSLA value was also higher than the preoperative CVT/NSLa value,which was statistically significant(130.2±8.0 vs 115.9±7.8,P<0.001).However,Δ CVT/NSLa value higher than Δ O-C2a,and its difference was statistically significant(14.3±5.6 vs 6.0±4.5,P<0.001).17 patients(68.6%)with improved SBQ score and relieved symptoms of airway obstruction after OCF were included in the airway obstruction reduction group;the other 8 patients(68.6%)were airway obstruction and reorganization.After OCF,the mean SBQ score improved from 5.5 ±2.1 to 4.2±2.0(P=0.030).However,there was no significant difference in preoperative O-C2a(17.0°±3.3° vs 15.4°±3.5°,P=0.279),postoperative O-C2a(22.7°±3.6° vs 22.1°±3.7°,P=0.704)and preoperative CVT/NSLa(117.5°±6.8°vs 112.5°±7.3°,P=0.107).There was a linear correlation between Δ CVT/NSLa and Δ SBQ(r=-0.612,R2=0.374,P<0.01).In addition,there is a linear correlation between Δ SBQ and ΔO-C2a(r=-0.576,R2=0.332,P<0.01).The R2 value of the former is greater than that of the latter.Conclusion:Different cervical sagittal sequence morphological parameters have different effects on oropharyngeal airway changes after OCF.In general,compared with the traditional craniocervical sagittal sequence parameter O-C2a,the correlation between CVT/NSLA and sleep quality is more obvious,and it has more clinical value in OCF.Chapter 2:The role of atlantooccipital flexion dysfunction in the pathogenesis of cervical spondylosisIntroduction:Cervical spondylosis(CS)is a common disease with a reported prevalence of 5%to 21%.More than half of people over 55 years old can see cervical degenerative changes on imaging.One statistic shows that from 1990 to 2000,the operation rate of cervical spondylosis increased by 90%in the American population.With the change of modern lifestyle and work style,the sedentary population increases,and the dependence on mobile devices,the current prevalence may be higher.The pathogenesis of CS is related to primary disc degeneration,reduction of intervertebral disc space and continuous pathological processes(such as osteophyte formation and hypertrophy of ligamentum flavum),which eventually leads to spinal canal and neural canal stenosis and related neurological symptoms and dysfunction.Previous studies have shown that abnormal atlantoaxial joint function is associated with cervical degeneration,presumably due to disordered muscle ligament balance system and mechanical stress conduction.Based on this,the purpose of this study is as follows:(Ⅰ)measure the O-C1(atlantooccipital)angle from the lateral film of cervical spine and determine its inter observer and intra observer reliability;(Ⅱ)study the relationship between O-C1 and CS during flexion and extension;(Ⅲ)discuss whether muscle dysfunction affects the normal function of the upper cervical spine.Methods:From January 2015 to may 2019,patients with CS were recruited from our hospital in this retrospective case-control study,and age/sex/body mass index(BMI)matched healthy control group was selected from subjects undergoing health examination.A total of 464 subjects were included in the study.There were 282 men and 182 women.The age of the patients ranged from 20 to 67 years old.The average age was 33.9 years old.CS patients were defined as case groups.They were further divided into non-surgical group and surgical group according to whether they received surgical treatment or not.There were 45 and 187 patients in the surgical and non-surgical groups,respectively,while the control group included 232 subjects.The angle between McGregor line and C1 line(O-C1 angle)was measured by images measured on lateral plain films of cervical spine including head in flexion position(F-OC)and neutral position(N-OC).The role of FOC in the pathogenesis of CS was analyzed by examining the relationship between foc(FOC=F-OC-N-OC)and neck disability index(NDI).Subject operating characteristic(ROC)curve analysis was performed to determine the optimal threshold for detecting increased risk of CS.Results:The average follow-up time was 51.6 months(25-115 months).The case group,especially the operation group,was older(55.8±11.2 vs 41.6±13.8 vs 23.5±5.5 years,P<0.001),and had a higher NDI score(12.2±4.5 vs 6.2±2.1vs 3.2±1.2,P<0.001)and a longer history of CS(10.5±9.5 vs 6.8±11.2 years,P<0.001).One way ANOVA showed that the difference of FOC between the control group and the case group was statistically significant(1.4°±1.2° vs 3.6°±1.9 ° vs 7.2°±2.0°,P<0.001).In addition,the post-hoc Tukey test showed that the FOC of the surgical group was lower than that of the non-surgical group(1.4°±1.2 ° vs 3.6 °±1.9°,P<0.001).FOC was used as the radiological prediction model to predict CS,and the cut off value was 4.2°.Using FOC as the radiological prediction model for predicting CS,the area under the curve(AUC)was 0.86(95%CI:0.78-0.92,P<0.001).In the univariate risk analysis model,logistic regression showed that the level of FOC was an independent risk factor and played an important role in the risk of CS.When the FOC is lower than 4.2 °(OR= 8.2;95%CI:6.4-10.0;P<0.001).There was a significant negative correlation between FOC level and NDI(r=-0.451,P= 0.016).Conclusions:Patients CS tend to have atlantooccipital joint stiffness.Cervical muscle dysfunction may accelerate the degeneration of the lower cervical spine by affecting the normal function of the upper cervical spine.This finding helps spine surgeons understand the pathological process of CS and implement appropriate preventive and therapeutic measures to delay or reduce the incidence of cervical spondylosis. |
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