Kim Jong Tae, Lee Ho Jin, Kim Jung Hee, Hong Jae Taek
Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, 56, Dongsu-ro Bupyeong-Gu, Incheon, 403-720, Republic of Korea.
Department of Neurosurgery, Seoul Medical Center, Seoul, Republic of Korea.
Eur Spine J. 2016 Dec;25(12):4188-4194. doi: 10.1007/s00586-016-4708-9. Epub 2016 Jul 21.
Unusual entrance of the vertebral artery into the cervical transverse foramen (UE-V2S) is a relatively common clinical anomaly. Because spinal surgeons should understand the anatomical characteristics and clinical implications of this condition, we aimed to provide a description based on a very large number of UE-V2S anomaly cases.
We retrospectively analyzed 2207 three-dimensional head-and-neck computed tomographic angiograms (CTAs) that did not have specific vascular abnormalities. After confirming which cases had an unusual vertebral artery (VA) entrance into the transverse foreman (TF), we measured their vertebral artery diameter (VAD), transverse foramen area (TFA) and bilateral pedicle width (PW) from C3 to C7. The shortest horizontal distance from the vertical line in the medial margin of the TF to VA (D-TFVA) was measured in the extra-osseous region to estimate the exact location of the extra-osseous VA, except at the C7 level.
An unusual V2 entrance was observed in 11.4 % (252 patients) of all 2207 consecutive patients and 6.5 % (268 courses) of all 4414 courses. The prevalence rankings for the different measures were as follows: unilateral UE-V2S = E5 > E4 > E7 > E3; bilateral UE-V2S = E5 (bilateral) > E4 (Rt) with E5 (Lt) > E4 (bilateral). Generally, the VAD of the anomaly side was statistically smaller than the normal contralateral side, which can induce a smaller TFA value at all sub-axial levels. Cervical pedicle fixation was preferable in the adjacent lower segment of unusual VA entrance level than the normal side in this study due to a broader PW, which was evident on the anomaly side. However, there was no statistical evidence that the side of the C7 entrance of the VA had a narrow PW. The lowest D-TFVA value was -3.8, indicating that we should take care not to exceed 3.8 mm medially into the vertical line of the medial TF wall during dissection when taking an anterior cervical approach.
To avoid an unexpected VA injury and to improve the efficiency of even routine cervical operations, spinal surgeons should determine whether the patient has a UE-V2S and have a full understanding of the clinical characteristics of this anomaly.
椎动脉异常进入颈椎横突孔（UE-V2S）是一种相对常见的临床异常情况。由于脊柱外科医生应了解这种情况的解剖学特征和临床意义，我们旨在基于大量UE-V2S异常病例进行描述。
我们回顾性分析了2207例无特定血管异常的三维头颈计算机断层血管造影（CTA）。在确认哪些病例存在椎动脉（VA）异常进入横突孔（TF）后，我们测量了从C3至C7的椎动脉直径（VAD）、横突孔面积（TFA）和双侧椎弓根宽度（PW）。在骨外区域测量从TF内侧缘垂直线到VA的最短水平距离（D-TFVA），以估计骨外VA的准确位置，但C7水平除外。
在所有2207例连续患者中，11.4%（252例患者）观察到异常的V2进入；在所有4414个节段中，6.5%（268个节段）观察到异常。不同测量指标的患病率排名如下：单侧UE-V2S = E5 > E4 > E7 > E3；双侧UE-V2S = E5（双侧）> E4（右侧）伴E5（左侧）> E4（双侧）。一般来说，异常侧的VAD在统计学上小于对侧正常侧，这在所有下颈椎节段均可导致较小的TFA值。在本研究中，由于异常侧椎弓根宽度更宽，在异常VA进入水平的相邻下节段进行颈椎椎弓根固定比正常侧更可取。然而，没有统计学证据表明VA在C7水平进入侧的椎弓根宽度狭窄。最低的D-TFVA值为-3.8，这表明在进行颈椎前路手术时，在解剖过程中应注意不要向TF内侧壁垂直线内侧超过3.8 mm。
为避免意外的VA损伤并提高常规颈椎手术的效率，脊柱外科医生应确定患者是否存在UE-V2S，并充分了解这种异常的临床特征。
