A MRI study of lumbar plexus in patients with degenerative lumbar scoliosis after extreme lateral interbody fusion

Abstract

To analyze the magnetic resonance neural imaging distribution of lumbar plexus in patients with degenerative lumbar scoliosis and evaluate its value and the safety of extreme lateral interbody fusion (XLIF). Three-dimensional fast imaging employing steady-state acquisition (3D FIESTA) sequences of lumbar spine were scanned on 19 patients with degenerative lumbar scoliosis, including levo scoliosis (n = 11) and dextro scoliosis (n = 8). All images were sent to workstation for multiplanar volume reconstruction to analyze the distribution of lumbar plexus from L1-2 to L4-5 level. The axial image distance (AID) was measured between anterior edge of lumbar plexus and sagittal central perpendicular line (SCPL). SCPL was drawn perpendicularly to the sagittal plane of intervertebral disc and passed through its central point. It was actually the pathway of guide wire implanting procedure and the ongoing axis of work channel during XLIF. With respect to SCPL, the distance with a positive value indicated posterior neural tissue whereas a negative value anterior neural tissue. The differences of AID were compared between convex and concave sides and among different cases and levels. From L1-2 to L4-5 level, the AID on the concave side in levo scoliosis or dextro scoliosis cases was (13.7 ± 2.5) mm/ (12.9 ± 5.5) mm, (8.3 ± 4.7) mm/ (8.5 ± 5.7) mm, (2.7 ± 3.6) mm/ (2.5 ± 7.2) mm and (-4.2 ± 3.8) mm/ (-3.8 ± 7.1) mm respectively. They were located significantly posteriorly to the relevant disc compared to those on the convex side at the same intervertebral space (P < 0.05). The differences of AID at the same side, concave or convex side, was significant (P < 0.05). No significant differences of lumbar plexus distribution existed between levo scoliosis and dextro scoliosis cases (P > 0.05). Lumbar plexus passes through psoas posteriorly to SCPL on both side at L1-2, L2-3 level and on the concave side at L3-4 level. And they shift anteriorly to SCPL on the convex side at L3-4 level and on both sides at L4-5 level. It indicates a ventral migration of lumbar plexus from L1-2 to L4-5 level. Preoperative magnetic resonance neural imaging is valuable for assessing the safety of XLIF approach. Operation from the concave may reduce the risk of injury to lumbar plexus.