The Relationship Of The Shear Wave Elastography Findings Of Patients With Unilateral Lumbar Disc Herniation And Clinical Characteristics

Objective The aim of this study was to investigate the clinical feasibility of shear wave elastography(SWE)in the evaluation of sciatic nerve in patients with unilateral lumbar disc herniation(LDH)and to find out whether the SWE findings of patients with unilateral LDH were related to clinical characteristics.Materials and methods For this purpose,20 patients with LDH who were hospitalized in the spinal surgery department of our hospital from January 2018 to April 2019 were recruited as the study group.The study group included patients(N=20;13 male,7female)with complaints of unilateral sciatica,with foraminal stenosis caused by one level of LDH(L4-L5 or L5-S1).An gender-and age-matched control group(N=27;16male,11 female)was included.Participants who met any of the following criteria were excluded:diabetes mellitus,any type of polyneuropathy,trauma,previous history of back surgery,or piriformis syndrome.The elastographic examination was performed with a Supersonic Aixplorer Ultrasound system(Supersonic Imagine,Aix en Provence,France)equipped with elastographic software and a 1-6MHz convex array transducer.The sciatic nerve was identified between the ischial tuberosity and the femoral greater trochanter on the axial plane.Then,the probe was rotated 90 ° to obtain a longitudinal imaging plane at the same level.Once the sciatic nerve was visualized on the longitudinal plane of the subgluteal region,the shear wave elastography examination was performed at the same level without compression.The operator fixed transducer during imaging acquisitions and the shear wave elastic modulus for each sciatic nerve was obtained.All the patients were examined on both the axial and longitudinal planes bilaterally at the same level.Record the following data:(1)the elastic modulus of the sciatic nerve at the subgluteal region;(2)the width and thickness of the sciatic nerve at this plane.The differences of elastic parameters among the groups were compared,and ROC curves were drawn to obtain the diagnostic boundary points of elastic parameters and evaluate their diagnostic efficiency.Result 1.The sciatic nerve stiffness measured on longitudinal planes of the affected side(20.4 ±4.6 k Pa)was significantly higher than unaffected side(12.9 ± 2.2k Pa)in the patient group(P < 0.001).Meanwhile,the control group with mean value of 12.7±2.1k Pa(left)and 13.5±1.9k Pa(right)showed significantly difference between the affected side(all P < 0.05).However,for the width and thickness of the sciatic nerve,there was no significant difference between the affected side and the unaffected side or the control group(P > 0.05).2.The elastic modulus of sciatic nerve obtained by SWE is moderately positively correlated with the duration of unilateral LDH,with a correlation coefficient of 0.60(ρ= 0.006).The longer the duration of unilateral lumbar disc herniation,the greater the elastic modulus of the sciatic nerve and the higher the stiffness of the sciatic nerve.3.The area under the ROC curve(AUC)of elastic parameters was 0.827 in patients with unilateral LDH.The optimal cutoff value of elastic paramater for diagnosis of sciatic neuropathy caused by unilateral LDH was 17.9 k Pa(sensitivity is 76% and specificity is95%).Conclusion Shear wave elastography can assess the stiffness of the sciatic nerve quantitatively.The sciatic nerve stiffness of patients with unilateral LDH have higher stiffness compared to control group.And the longer history of the unilateral LDH,the higher of the SWE findings.SWE will have a promising prospect for many patients with unilateral LDH in monitoring stiffness during rehabilitation and before or after surgery.