The investigation of the lateral atlanto-dental interval of atlanto-axial joint by multi-slice spiral CT / 中华放射学杂志

ABSTRACT

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. x2 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.