椎管减压术后神经根沉降征的变化研究

Changes of Nerve Root Sedimentation Sign in Patients with LSS who Undergo Spinal Decompression Surgery

目的通过比较神经根沉降征在腰椎管狭窄症患者减压术前后的变化,来研究神经根沉降征与硬膜外压力变化的关系,为SedSign的形成机制研究提供参考。方法本研究选取20例患者,分为阳性SedSign组和阴性SedSign组,阳性SedSign组(n=10)为最小硬膜囊横截面积(cross-sectional area,CSA)<80mm^2、行走距离<50m、阳性SedSign、单节段中央型LSS患者;阴性SedSign组(n=10)为最小CSA>120mm^2、50m<行走距离<500m、阴性SedSign、非LSS患者(单节段的腰椎滑移患者或单节段的腰椎间盘突出症患者)。所有患者经后路椎管减压术,术后评估手术疗效好代表其减压的彻底性,术后4~30个月复查腰椎MRI,分别比较两组患者手术前后神经根沉降征的变化。结果阳性SedSign组内10例患者术后阳性SedSign出现部位仍然为阳性,阴性SedSign组内10例患者手术后SedSign仍为阴性。结论虽然腰椎管减压手术降低了椎管狭窄段硬膜外压力,但是神经根沉降征无改变,故椎管狭窄段硬膜外压力增高可能不是形成阳性SedSign的主要原因。

Objective To compare the changes of nerve root sedimentation sign in patients with LSS who undergo spinal decompres- sion surgery and to study the association between epidural pressure change and nerve root sedimentation sign. Methods To simulate the design of B arz＇ study, we included 10 cases of LSS （40% women, median age 72 years） with positive nerve root sedimentation sign and 10 patients with lumbar spinal disorders （40% women, median age 67 years） with negative nerve root sedimentation sign. The patients in the first group （n = 10） had center canal stenosis for one spinal level （mono - segment） , with a walking distance less than 50 meters in the walking test. The nerve root sedimentation sign was positive on lumbar MR images, with a cross - sectional surface area （CSA） 〈 80mm2. A second group （n = 10） were non- LSS patients （one level lumbar spondylolisthesis, one level lumbar disc herniation） with negative sedimentation sign （ the minimal CSA 〉 120mm2 , walking distance between 50m and 500m. All patients underwent lumbar canal decom- pression surgery. Lumbar MR imaging was repeated 4 to 18 months after the index surgery. On axial image, sedimentation sign were re - evaluated and compared with those of pre - surgery. Results The sedimentation sign remained positive after surgery for all 10 patients with LSS and positive sedimentation sign. In patients with lumbar spinal disorders and negative sedimentation sign, the sedimentation sign remained negative after surgery. Conclusion Although the epidural pressure was significantly reduced after decompression surgery such as laminectomy, a positive sedimentation sign remains. Our data suggest that epidural pressure may not be an important cause for the patho- genesis of positive sedimentation sign.