[Study on related influencing factors on the occurrence of redundant sign in the cauda equina in lumbar spinal stenosis].

Objective: To analyze the relational factors influencing the formation of cauda equina redundant nerve roots (RNRs) of the lumbar spinal stenosis.

Methods: Clinical data of 116 patients with lumbar spinal stenosis treated from January 2016 to June 2019 were retrospectively analyzed. The patients were divided into redundant nerve roots(RNRs) group and non-RNRs group based on the presence or absence of RNRs on sagittal T2-weighted MRI. In the non-RNRs group, there were 74 patients, including 38 males and 36 females with an average age of (62.00±10.41) years old, the body mass index (BMI) was (23.09±2.22) kg·m;the maximum stenosis segment was L-L in 12 cases, L-L in 38, L-L in 20, and LS in 4, respectively. In the RNRs group, there were 42 patients, including 18 males and 24 females with an average age of (63.36±8.73) years old, the BMI was (22.63±2.60) kg·m;the maximum stenosis segment was L-L in 3 cases, L-L in 9, L-L in 27 and LS in 3, respectively. MRI was performed in the supine position to observe the conshape and morphology of the redundant nerve in the sagittal position. The preoperative low back and leg pain visual analogue scale(VAS), and preoperative Oswestry disability index(ODI) were analyzed, and the rate of spondylolisthesis and ligamentum flavum hypertrophy were compared. Simultaneously, the inter-vertebral height, intervertebral foramen height, inter-vertebral height+vertebral height, median sagittal diameter at the inter-vertebral space level(DIW-MSD), median sagittal diameter at the pedicel level(DV-MSD), range of motion(ROM) of the stenotic segment were measured and analyzed.

Results: Among the 116 patients with lumbar spinal stenosis, 42 patients developed RNRs, with an incidence of 36.2%. There were no significant differences in gender, age, BMI, preoperative VAS for lumbar and leg pain and ODI between two groups(>0.05). There were statistically significant differences regard to the duration of symptoms and the rate of spondylolisthesis and ligamentum flavum hypertrophy (<0.05);the inter-vertebral height, intervertebral foramen height, inter-vertebral height+vertebral height, DIW-MSD, ROM of the stenotic segment were also significantly different between two groups(<0.05). However, there was no significant difference in DV-MSD between two groups(>0.05).

Conclusion: The inter-vertebral height, inter-vertebral foramen height, inter-vertebral height+vertebral height, DIW-MSD and ROM of the stenotic segment were the crucial factors related to RNRs in lumbar spinal stenosis.