Evaluation of Clinical Symptoms of Unilateral S1 Nerve Injury Caused by Disc Herniation the via High Resolution MRI and DTI

Abstract

Background: The status of the herniated disc or nucleus pulposus and the extent of injury and clinical symptoms of the compressed S1 nerve fiber bundle were evaluated by high-resolution Magnetic resonance imaging (MRI) and Diffusion tensor imaging (DTI) techniques.

Methods: Forty-two clinically proven patients with unilateral S1 nerve root compression were selected as the case group (n=42), and 20 healthy volunteers were selected as the control group (n=20). The general data, MRI features and DTI parameters were compared between groups. The effective indicators of S1 neurologic fiber bundle damage were screened by univariate logistic regression analysis and receiver operating characteristic (ROC) curve, and multi-factor logistic regression models were constructed to analyze the diagnostic efficiency of each model.

Results: There were no significant differences in age, gender, height, weight, fractional anisotropy (FA) value and apparent diffusion coefficient (ADC) value on both sides of S1 nerve root between groups (P >0.05). The FA value and ADC value of the nerve root on the affected side of the patient were significantly different from those on the healthy side and those on the corresponding side of the control group (all P <0.05), and all of them were effective indicators of the damage of S1 nerve. The sensitivity, specificity and area under the curve of the damaged nerve fiber bundle were detected by multi-factor logistic regression models constructed with FA+rFA and FA+rFA+rADC of the affected nerve root, respectively 95.20%, 72.00%, 0.939, and 97.60%, 80.00%, 0.944.

Conclusion: High-resolution MRI and DTI can quantitatively evaluate the degree of nerve fiber bundle injury and clinical symptoms caused by lumbar disc herniation.

Keywords: DTI; apparent diffusion coefficient; fractional anisotropy; high-resolution MRI; lumbar disc herniation.

Figure 1

Comparison of FA and ADC values between the case group (patients with unilateral S1 nerve root compression) and the control group (healthy volunteers). (A) Apparent diffusion coefficient (ADC) values in the diseased side (blue), normal side (red), and volunteer group (green); (B) ADC ratio (rADC) comparing the diseased side (blue) to the volunteer group (red); (C) Fractional anisotropy (FA) values in the diseased side (blue), normal side (red), and volunteer group (green); (D) FA ratio (rFA) comparing the diseased side (blue) to the volunteer group (red).

Figure 2

Correlation analysis of DTI parameters on the diseased side. (A) Correlation between JOA and ADC; (B) Correlation between JOA and rADC; (C) Correlation between JOA and FA; (D) Correlation between JOA and rFA.

Figure 3

ROC curve of nerve fiber bundle damage. (A) FA, rFA, ADC and rAD; (B) Model 1 and Model 2.Significant differences between the curves for the case and control groups are observed, indicating the effectiveness of the DTI parameters (FA, rFA, and rADC) in distinguishing nerve fiber damage.

Figure 4

Healthy male volunteer, 30 years old, with no history of back and leg pain. (A) T2WI sagittal view showing no disc herniation. (B) T2WI transverse view showing no abnormalities. (C) DTT (Diffusion Tensor Tractography) image showing intact and symmetric L5 and S1 nerve fiber bundles, with no evidence of thinning, interruption, or missing fibers. (A) the frontal view, meaning it is viewed from anterior to posterior.

Figure 5

Male volunteer, 40 years old, L5/S1 LDH(RIGHT). (A) T2WI showing a curved indentation and substantial compression of the dural sac at the L5/S1 disc, located posteriorly on the right. (B) T2WI transverse view showing a posterior shift of the nucleus pulposus on the right, loss of the L5 right recess, compression of the ipsilateral L5 and S1 nerve roots, and removal of the foraminal adipose space. (C) Anatomical image showing the deformation and thinning of the affected nerve roots. (D) DTT image showing asymmetric nerve fiber bundles, with deformation and local discontinuity in the right S1 nerve root at the herniation site.