Pros of the contralateral (over-the-top) approach to intra/extraforaminal lumbar disc herniations at the L5-S1 level

Abstract

Background: Minimally invasive approaches to intra/extraforaminal lumbar disc herniations offer the benefit of less bone removal and reduced nerve root manipulation at the L5-S1 level. Moreover, the potential to better preserve stability.

Methods: Here, we summarized the efficacy of the contralateral approach to intraforaminal/extraforaminal lumbar disc herniations particularly focusing on the L5-S1 level. Variables studied included the level of these disc herniations, their locations within the foramina, and the anatomy of the facet joints.

Results: A major "pro" for the contralateral interlaminar procedure at the L5-S1 level is that it does not require facet joint removal, or with a spondylotic facet, <30% joint excision, to directly visualize the intraforaminal/ extraforaminal nerve root. It, therefore, reduces the risk of creating iatrogenic instability, while offering a higher certitude of adequate nerve root visualization, decompression, and safer disc removal.

Conclusion: The contralateral interlaminar approach is more suitable for all types of intra/extraforaminal disc herniations at the L5/S1 level. The most specific benefit of this approach is its avoidance of disruption/significant removal (i.e., <30%) of the facet joint to adequately expose the foraminal L5 nerve root, and more safely remove the intra/extraforaminal disc herniation.

Keywords: Contralateral approach; Crossover technique; Intraforaminal lumbar disc herniation; Minimally invasive spine surgery; Over-the-top access; Spinal stability.

Figure 1:

(a) The presurgical T2 axial MRI arrow showed an extraforaminal disc herniation at the L5-S1 level with compression of the L5 root (white arrow). (b) The postsurgical T2 axial MRI images showed the disc herniation removed without violation of the facet joint (white arrow).

Figure 2:

(a) The presurgical T2 axial MRI image and white arrow pointed to the left extruded disc herniation and (b) the presurgical T2 axial MRI showed a yellow arrow pointing to a purely intraforaminal disc herniation. (c) The postsurgical axial T2 MRI images showed removal of the left extruded disc herniation and (d) the postsurgical axial T2 MRI images showed the right intraforaminal disc herniation removed without facet violation.

Figure 3:

(a) The axial MRI images show a preforaminal and intraforaminal disc herniation (white arrow). (b) The sagittal T2 MRI showed cranial extension of the disc herniation (white arrow).

Figure 4:

(a) On the presurgical axial T2 MRI images at the L3-L4 level, the white arrow showed the correct extraforaminal trajectory indicating there would be no need for facet joint drilling, (b) the presurgical axial T2 MRI images at the L4-L5 level that included measurement of the facet joint complex, indicated possible facet joint removal, would be necessitated with an extraforaminal approach (i.e., 22.7 mm and 9.2 mm). Note, the white arrow indicated the appropriate extraforaminal trajectory, (c) on the presurgical sagittal T2 MRI, the white arrows pointed to an intraforaminal disc herniation at the L3-L4 and L4-L5 levels.

Figure 5:

The ipsilateral approach to an intraforaminal herniated lumbar disk does not require exposure below the spinous process. However, it is limited laterally by the facet joints, thus making part of the disc herniation not directly/readily accessible. The red arrow indicated the surgical trajectory. The black lines delimitate the initial surgical exposition to approach the hernia. (Figure 5 by Dr-Andrea Ciuffi).

Figure 6:

The contralateral approach allows for the development of a surgical corridor below the spinous process that with appropriate angulation between the dural sac and the distal facet joints, allows for direct access to the intraforaminal herniated disk. The red arrow indicated the surgical trajectory. The black lines delimitate the initial surgical exposition to approach the hernia. (Figure 6 by Dr. Andrea Ciuffi).