The Relationship Between The Changes Of Spinal Cord Signal In Thoracic Spinal Stenosis Caused By The Ossification Of Ligamentum Flavum And The Outcome Of Surgery

Objective:To investigate the relationship between the signal changes in the MRI T2-weighted image of the intraspinal spinal cord in thoracic spinal stenosis patients and their prognosis.Methods:A total of 69 patients with ossification of ligamentum flavum of thoracic spine that underwent surgical treatment in our hospital between 2014.01-2018.01 were enrolled.All patients received thoracic spine CT examination to confirm the thoracic spinal stenosis caused by ossification of the thoracic ligamentum flavum.Preoperative MRI examination was performed to confirm the signal conditions of spinal cord.According to the intramedullary signal of thoracic spine shown by MRI,the patients were divided into different groups:Group A with normal intraspinal signal including 44 patients with average age of 59.4± 10.3 years old,male ratio of 43.2%,and the average duration of disease of 12.0 months.The average preoperative JOA score of group A was 6.5±1.0 points,including 13 patients with grade Ⅲ muscle strength,27 patients with grade Ⅳmuscle strength,and 4 patients with grade V muscle strength before the surgery.Group B included 25 patients demonstrating signal changes in the spinal cord,with the average age of 63.7± 1.0 years old,male ratio of 40.0%,and average duration of disease of about 12.0 months.The average preoperative JOA score of Group B was 5.6± 1.1 points,including 11 people with grade Ⅲ muscle strength,14 people with grade Ⅳ muscle strength,and 0 people with grade Ⅴ muscle strength in the lower limbs before the surgery.All patients underwent posterior approach thoracolumbar decompression and internal fixation.The JOA score and the improvement of lower limb muscle strength were evaluated before the surgery,3 months after the surgery,and at last follow-up.Results:In group A,the JOA score was 8.2±1.1 points and the JOA improvement rate was 38.4±18.5%at 3 months after the surgery,including 2 patients with grade Ⅲ muscle strength,24 patients with grade Ⅳ muscle strength,and 18 patients with grade Ⅴ muscle strength.The average JOA score of Group A at the last follow-up was 9.4±1.0 points,and the final JOA improvement rate was 67.3±19.6%,including 1 patient with grade Ⅲmuscle strength,7 patients with grade Ⅳ muscle strength,and 36 patients with grade Ⅴmuscle strength.At 3 months after the surgery,the average JOA score of group B was 7.2±1.1 points,and the improvement rate was 28.4±11.7%,including 7 patients with grade Ⅲ muscle strength,15 patients with grade Ⅳ muscle strength,and 3 patients with grade V muscle strength.The JOA score of Group B at the last follow-up was 8.3± 1.2,and the improvement rate was 51.2± 17.3%,including 2 patients with grade Ⅲ muscle strength,15 patients with grade Ⅳ muscle strength,and 8 patients with grade V muscle strength.There was an interaction between grouping of patients and follow-up time(F=5.006,P=0.008).The JOA scores of Group A were significantly lower than that of Group B before surgery,3 months after the surgery and at the last follow-up(P<0.05).In each group,the JOA scores were significantly improved at 3 months after surgery compared with those before surgery,and at the last follow-up compared with 3 months after surgery.(P<0.05).The JOA score increased with longer follow-up time(P<0.001).There was significant improvement in muscle strength at 3 months after surgery compared with those before surgery,and at the last follow-up compared with 3 months after surgery(P<0.05).The muscle strength improvement rate of group A was higher than that of group B at each follow-up time(P<0.05).Conclusion:1.There was no significant difference in age composition,sex ratio,disease duration and clinical symptom distribution of TOLF spinal cord MRI T2-weighted imaging in patients with normal signal.2.There was no significant correlation between the changes in T2-weighted MRI images of TOLF spinal cord and the difficulty of surgery.3.For patients with preoperative high signal changes in the T2-weighted MRI images of the spinal cord,surgical treatment can achieve certain efficacy,but the prognosis is worse than that of patients with no signal changes in the spinal cord.4.The selection of surgery and intraoperative operation should be cautious,preoperative communication with the patient should be fully completed and detailed signing procedures.