The compression of L5 nerve root, single or double sites?— radiographic graded signs, intra-operative detect technique and clinical outcomes

Ai-Min Wu, Kai Zhang, Xun-Lin Li, Xiao-Fei Cheng, Tang-Jun Zhou, Lin Du, Chen Chen, Hai- Jun Tian, Xiao-Jiang Sun, Chang-Qing Zhao, Yan Michael Li, Jie Zhao


Background: The L5 nerve root could be compressed at both L4–5 and L5–S1 regions. If L5 nerve root has confirmed compression at L4–5 level and questionable compression at L5–S1 foramina, performing both surgeries at L4–5 and L5–S1 levels may induce unnecessary extra surgery on L5–S1; however, ignoring foraminal stenosis of L5/S1 may require re-exploration.

Methods: Two hundred seventeen patients with L5 nerve root compressed at L4–5 lateral access were performed with L4–5 decompression and interbody fusion. Lee et al. grade classification was used to assess the foraminal stenosis of L5–S1 preoperatively. Nerve root probe was designed and used to detect if there were foraminal stenosis at L5–S1 level that compressing the exiting L5 nerve root. Visual analog scale (VAS) of low back pain, leg pain and Oswestry Disability Index (ODI) were used to assess clinical outcomes.

Results: For all of 217 patients who underwent L4–5 surgery, L5–S1 foramina were preoperatively assessed as: grade 0: 125 cases, grade 1: 58 cases, grade 2: 23 cases, and grade 3: 11 cases. After intra-operative L5 nerve root detection, 11/11 patients with grade 3 radiographic foraminal stenosis, 6/23 (26.1%) with grade 2 and 2/58 (3.4%) who had grade 1 underwent L4–5 and L5–S1 transforaminal lumbar interbody fusion (TLIF), the others received only L4–5 TLIF. Compared to pre-operative baseline data, both L4–5 TLIF and L4–5 and L5–S1 TLIF groups had significant decreased VAS of low back pain and leg pain, and ODI at 3 and 24 months after operation.

Conclusions: We suggested that our novel nerve root probe combined with pre-operative radiographic grade may be helpful to surgeons to identify the single or double compression of L5 nerve root and make a more precise surgical strategy to improve surgical outcome than the method depended on pre-operative radiographic grade alone.