Spine Specialists On-Call: Spinal Nerve Compression and Unilateral Transforaminal Lumbar Interbody Fusion (TLIF)
Part One of Three
Nerve Compression in the Low Back
Nerve compression in the low back (lumbar spine) may be associated with spinal instability, worsening of a pre-existing deformity, or failed fusion. Spinal nerve compression may cause neurologic compromise resulting in symptoms such as pain, numbness, and weakness. If non-operative treatments are ineffective, spine surgery may be offered to help alleviate symptoms.
Spine Surgery Overview
The goal of lumbar spine surgery typically involves removing pressure off spinal nerves, a procedure called 'nerve decompression'. There are different types of surgical approaches (or exposures) to the spine such as: anterior (front), posterior (rear), and transforaminal (through/across the nerve passageways, called foramen). The surgical approach chosen is dependent on the patient's specific disorder to be addressed during surgery.
Sometimes spine surgery includes implants (e.g. cages, rods, screws) and fusion. A common term is 'interbody fusion' meaning the space(s) between the intervertebral body(ies) are instrumented and fused together. Implants or instrumentation and fusion are used to stabilize the spine. Typically after a discectomy (disc removal) the spine requires some reconstructive work to stabilize it -- often called fixation or instrumentation, it is combined with bone graft to facilitate fusion. It can take several months for the spinal segment to fuse to create a solid and stable construct.
There are several techniques the surgeon can use. The primary differences between the techniques listed below are the surgical 'approach' to the spine.
·Anterior Lumbar Interbody Fusion (ALIF)
·Posterior Lumbar Interbody Fusion (PLIF)
·Transforaminal Lumbar Interbody Fusion (TLIF)
Revision Spine Surgery
Cases involving revision surgery for a previously failed spinal fusion (termed 'pseudoarthrosis') have led doctors to identify certain factors that may predispose a patient to persistent pain or post-operative problems following reconstructive lumbar spine surgery. Since the early days of spinal fusion, it has been well-recognized that successful nerve decompression was not always associated with a successful fusion, as evidenced by clinical examination and/or x-ray (radiograph). In some instances, the patient's overall outcome remained excellent and further intervention was not necessary. However failed fusion and related difficulties have led surgeons to devise better techniques to maximize successful fusion outcomes.
Sometimes there is anatomical disease (e.g. infection) in the anterior spinal column that involves the disc endplates or disc itself. This may contribute to the patient's pre-operative symptoms. In such a case, the surgeon may consider incorporating both the front and middle columns of the spine in the fusion construct (e.g. rods, screws, cages).
However, there are instances, especially in the degenerative spine, when the surgeon is required to perform surgery from a posterior approach. It is in this situation that the Posterior Lumbar Interbody Fusion (PLIF) technique may best be applied. Although the PLIF technique from a bilateral (left and right sides) approach is well-known in the clinical and academic literature, the development of the unilateral (one-sided) Transforaminal Lumbar Interbody Fusion (TLIF) technique has allowed the surgeon to approach the interbody disc space posteriorly in a more efficient and isolated fashion, thereby reducing risk of injury to nearby nerve structures.