Cervical pedicle accompanied vertebral artery dominance： morphometric measurement of cervical pedicle and its surrounding structure using 3D-CT

English Keywords:Vertebral artery dominance  Cervical pedicle  Morphology

English Abstract:

  【Abstract】 Objectives： The purpose of this retrospective study was to observe the morphometric characteristics of lower cervical pedicles with dominant vertebral artery(vertebral artery diameter in one side is at least 0.8mm larger than contralateral side) and its surrounding structure，analyze the influence to cervical pedicle screw(CPS) implantation. Methods: 166 consecutive patients who underwent cervical 3D-CT angiography were enrolled in this study. Patients who had dominant artery(difference of ≥0.8mm between the widths of two vertebral artery) were selected to perform the measurements. The measurements included long axis diameter of the VA, short axis of the VA, pedicle outer width(POW), lateral pedicle border to vertebral artery(LPVA) and area of transverse foramen(ATF). Vertebral artery diameter (VAD)= (long axis diameter of the VA+short axis of the VA)/2, area of VA（AVA）=π×(VAD/2)2 residuary area of transverse foramen(RATF)=ATF-AVA. Occupation ratio of transverse foramen(ORTF)=AVA/ATF. Differences of all parameters between the two were analyzed. Results: The proportion of left VA dominance was 75% and 25% of the right. The mean VAD of dominant side was 3.78±0.49mm, which was 2.29±0.53mm of nondominant side. POW of dominant side and non-dominant side was 5.1±1.0mm and 5.5±0.9mm,LPVA was 1.0±0.5mm and 1.2±0.6mm; ATF was 29.0±6.9mm2 and 20.4±5.4mm2; ORTF was (40.5±8.5)% and (22.6±8.9)%, respectively. Parameters comparison between the two sides: POW, LPVA of dominant side was smaller than non-dominant side, ATF and ORTF was opposite, these results was statistically significant (P<0.05). The Pearson correlation coefficient between POW and VAD was -0.094, ATF and VAD was 0.549(P<0.05), showing positive correlation between ATF and VAD, but negative correlation between POW and VAD. The proportion of POW<4mm in VA dominant side was higher than non-dominant side. C3 has the most high rate(19.1%) and decrease caudally. Vertical comparison among dominant side shows all parameters were lower at C3, C4 but increase slightly at C5, C6. Conclusions: POW and LPVA of dominant side is smaller than those of nondominant side, ORTF and the ratio of POW<4mm are higher in dominant side， the risk of CPS implantation is higher in dominant side.