寰枢关节齿突侧块间隙的多层螺旋CT研究

The investigation of the lateral atlanto-dental interval of atlanto-axial joint by multi-slice spiral CT

目的探讨寰枢关节齿突侧块间隙（LADI）的影像特征及其在寰枢关节病变诊断中的意义。方法240名无寰枢关节病变的健康志愿者和32例临床确诊的寰枢关节脱位或半脱位患者分别行中立位和左右旋转功能位CT扫描，观察其LADI的影像表现，并对左右LADI和双侧齿突侧块间距差（VBLADI）进行测量和对照分析。正常对照组各年龄男女组间双侧LADI不对称阳性率比较用Ⅹ^2检验，正常对照组VBLADI与寰枢椎旋转功能相关性的判定用Pearson双侧检验，正常对照组与病变组比较用四格表精确检验法。结果（1）正常对照组：240名志愿者双侧LADI不对称的发生率为85．00％（204／240）；〈15岁年龄组60名，lVBLADI中位数为0．850mm，95％百分位数（P95％）=2．450mm，〉2．450mm者2名；≥15岁年龄组180名，｜VBLADI｜中位数0．700mm，P95%=2．051mm，〉2．051mm者10名。VBLADI（-2．146—2．114mm，中位数0．000mm）与寰枢椎相对左旋角度（LA：22．949°～44．649°，中位数34．500°）、右旋角度（RA：25．284°～45．334°，中位数35．300°）、左右旋角度差（VLRA：-11．643°-8．623°，中位数0．000°）没有相关性（r=-0．030、-0．005、0．026，P值均〉0．05）。（2）病例组：32例患者中，〈15岁者25例，≥15岁者7例。寰枢关节侧方半脱位（AALSD）17例，其中〈15岁者16例，｜VBLADI｜中位数为3．350mm，〉2．450mm者14例，≥15岁者1例VBLADIl≥2．051mm。寰枢关节旋转脱位（AARD）7例，其中4例〈15岁者｜VBLAD｜均〈2．450mm，中位数为1．200mm，3例≥15岁者｜VBLADI｜均〈2．051mm，7例AARD均显示一侧LADI呈伞形。寰枢关节复合脱位（AACD）8例，其中5例〈15岁者〉2．450mm者4例，成人3例｜VBLADI｜均≥2．051mm。AALSD组和AACD组｜VBLAD｜≥P95％者多于正常组，差异有统计学意义（p均〈0．01），AARD组与正常组间差异无统计学意义（P=0．738）。结论双侧LADI不对称既可见于正常人，也可能是一种病理状态，应结合临床表现和其他影像征象综合分析。

Objective To explore imaging features of the lateral atlanto-dental interval （LADI） of atlanto-axial joint and its value in the diagnosis of atlanto-axial joint dislocation/subluxation. Methods Two hurdred and forty healthy volunteers without atlanto-axial joint dysfunction and 32 patients with torticollis and/or functional impairment at atlanto-axial joint were enrolled into this study. All subjects were examined with multi-slice CT in both neutral and max rotation positions to the left/right. Clinical endpoints including VBLADI, variance range of the VBLADI and asymmetric conditions were evaluated. Х^2 test is used to evaluate the variance of incidence of bilateral LADI asymmetry in different age groups, Pearson-test （2-tailed） is used to evaluate the correlation between VBLADI and rotary function of atlanto-axial joint, precise test of fourfold table is used to compare normal group with patient groups. Results （ 1 ） In the normal control group ： asymmetry of bilateral LADI were observed in 204 among 240 （ 85.00% ） healthy volunteers including 60 youngsters（ 〈 15 years） and 180 adults（ ≥ 15 years）. The median and P95% of ｜ VBLADI ｜ were 0. 850 mm,2. 450 mm in the young （ 〈 15 years） and 0. 700 mm,2. 051 mm in the adult （≥15 years）, there were 2 and 10 volunteers whose｜ VBLADI ｜≥P95% in the young and in the adult respectively. There was no correlation between VBLADI （ -2. 146 to 2. 114 mm, Median 0. 000 mm） and LA （22. 949° to 44. 649°, Median 34. 500°）, RA （25. 284°to 45. 334°, Median 35. 300°）, VLRA （ - 11. 643° to 8. 623 °, median 0. 000 ° ） respectively in normal people （ r = - 0. 030, - 0. 005,0. 026, P 〉 0. 05 ）. （ 2 ） In the study with 32 patients including 25 youngsters （ 〈 15 years） and 7 adults （ ≥15 years）. Seventeen of 32 had atlanto-axial lateral subdislocation （AALSD）, in 16 youngsters （ 〈 15 years）, the median of the ｜ VBLADI ｜ was 3. 350 mm and 14 cases ｜ VBLADI ｜≥2. 450 mm;1 adult patient（ ≥15 years） had ｜ VBLADI ｜≥ 2.051 mm; 7 of 32 patients had atlanto-axial rotatory dislocation （AARD） including 4 youngsters ｜ VBLADI ｜ 〈2.450 mm,median 1.200 mm,3 adults ｜ VBLADI ｜ 〈2.051 mm,all of the 7 patients with AARD had unilateral parasol LADI in neutral position;8 of 32 patients had atlanto-axial complicated dislocation（AACD） including 5 youngsters ｜ VBLADI ｜ ≥2. 450 mm,3 adults ｜ VBLADI ｜ ≥ 2. 051 mm. There are more cases whose ｜ VBLADI ｜≥ P95% in group AALSD and group AACD than in abnormal group（ P 〈 0. 01 ） ,but there is no difference between group AARD and normal group（ P = 0. 738 ）. Conclusion The imaging finding of ＂asymmetry of bilateral LADI＂ may be either a physiological variation or a pathological condition, clinical manifestations and other imaging findings should be evaluated to make a diagnosis.