Smith William D, Youssef Jim A, Christian Ginger, Serrano Sherrie, Hyde Jonathan A
Western Regional Center for Brain and Spine Surgery, Las Vegas, NV, USA.
J Spinal Disord Tech. 2012 Jul;25(5):285-91. doi: 10.1097/BSD.0b013e31821e262f.
Retrospective review.
To determine if lumbarized sacra at the L5-6 level (functional L4-5) are a contraindication to a lateral transpsoas approach.
Transitional vertebrae at the lumbosacral junction present mechanical and morphologic changes, though these changes have not been characterized with respect to the feasibility of a lateral transpsoas approach.
Three hundred fifty-one patients were scheduled for lumbar interbody fusion using a mini-open lateral transpsoas approach (XLIF) at L4-5 from 2004 to 2008 at a single institution. In patients with 6 lumbar vertebrae, accessibility, based on neuromonitoring, of the L5-6 level (functional L4-5) was reviewed. Qualitative assessments using axial magnetic resonance imaging (MRI) were performed and compared with a sample of patients with normal anatomy treated at L4-5.
Of the 351 patients scheduled for treatment at L4-5, 10 (2.8%) were determined to have 6 lumbar vertebrae with the symptomatic level at L5-6. Of those 10, 2 (20%) could be treated using a lateral transpsoas approach, and 8 (80%) were converted to another approach after a corridor through the psoas muscle was not found, based on neuromonitoring feedback. Review of axial MRI showed a teardrop-shaped psoas detached from the lateral border of the disc space in patients with transitional anatomy unapproachable at L5-6, resemblant of L5-S1 in normal anatomy. In the 2 patients who could be safely approached, the psoas anatomy at L5-6 was similar to a normal L4-5 level, with a domed/helmet shape, attached laterally to the disc space.
Treating the L5-6 level using a lateral transpsoas approach in individuals with lumbarized sacra can be challenging due to anatomy more similar to the L5-S1 level in normal patients. Preoperative planning using axial MRI and intraoperative adherence to advanced neuromonitoring can aid in identifying and avoiding injury in these rare patients.
回顾性研究。
确定L5 - 6水平（功能上的L4 - 5）的腰椎化骶骨是否是经腰大肌外侧入路的禁忌症。
腰骶交界处的过渡椎体会出现力学和形态学变化，尽管这些变化尚未就经腰大肌外侧入路的可行性进行描述。
2004年至2008年在一家机构，351例患者计划采用微创开放经腰大肌外侧入路（XLIF）在L4 - 5节段进行腰椎椎间融合术。对于有6个腰椎椎体的患者，基于神经监测评估L5 - 6水平（功能上的L4 - 5）的可达性。使用轴向磁共振成像（MRI）进行定性评估，并与在L4 - 5节段接受治疗的正常解剖结构患者样本进行比较。
在计划于L4 - 5节段治疗的351例患者中，10例（2.8%）被确定有6个腰椎椎体，症状节段在L5 - 6。在这10例患者中，2例（20%）可以采用经腰大肌外侧入路治疗，8例（80%）在根据神经监测反馈未找到通过腰大肌的通道后改为另一种入路。对轴向MRI的回顾显示，在L5 - 6节段难以接近的过渡解剖结构患者中，腰大肌呈泪滴形，从椎间盘间隙的外侧边缘分离，类似于正常解剖结构中的L5 - S1。在2例可以安全接近的患者中，L5 - 6节段的腰大肌解剖结构类似于正常的L4 - 5水平，呈圆顶/头盔形状，外侧附着于椎间盘间隙。
对于腰椎化骶骨的个体，采用经腰大肌外侧入路治疗L5 - 6节段可能具有挑战性，因为其解剖结构更类似于正常患者的L5 - S1水平。术前使用轴向MRI进行规划并在术中坚持先进的神经监测有助于在这些罕见患者中识别并避免损伤。
