Mechanical properties of nerve roots and rami radiculares isolated from fresh pig spinal cords

No reports have described experiments designed to determine the strength characteristics of spinal nerve roots and rami radiculares for the purpose of explaining the complexity of symptoms of medullary cone lesions and cauda equina syndrome. In this study, to explain the pathogenesis of cauda equina syndrome, monoaxial tensile tests were performed to determine the strength characteristics of spinal nerve roots and rami radiculares, and analysis was conducted to evaluate the stress-strain relationship and strength characteristics. Using the same tensile test device, the nerve root and ramus radiculares isolated from the spinal cords of pigs were subjected to the tensile test and stress relaxation test at load strain rates of 0.1, 1, 10, and 100 s-1 under identical settings. The tensile strength of the nerve root was not rate dependent, while the ramus radiculares tensile strength tended to decrease as the strain rate increased. These findings provide important insights into cauda equina symptoms, radiculopathy, and clinical symptoms of the medullary cone.

Correlation of lumbar lateral recess stenosis in magnetic resonance imaging and clinical symptoms

AIM To assess the correlation of lateral recess stenosis(LRS) of lumbar segments L4/5 and L5/S1 and the Oswestry Disability Index(ODI).METHODS Nine hundred and twenty-seven patients with history of low back pain were included in this uncontrolled study.On magnetic resonance images(MRI) the lateral recesses(LR) at lumbar levels L4/5 and L5/S1 were evaluated and each nerve root was classified into a 4-point grading scale(Grade 0-3) as normal,not deviated,deviated or compressed.Patient symptoms and disability were assessed using ODI.The Spearman's rank correlation coefficient was used for statistical analysis(P < 0.05).RESULTS Approximately half of the LR revealed stenosis(grade 1-3;52% at level L4/5 and 42% at level L5/S1) with 2.2% and 1.9% respectively reveal a nerve root compression.The ODI score ranged from 0%-91.11% with an arithmetic mean of 34.06% ± 16.89%.We observed a very weak statistically significant positive correlation between ODI and LRS at lumbar levels L4/5 and L5/S1,each bilaterally(L4/5 left:rho < 0.105,P < 0.01;L4/5 right:rho < 0.111,P < 0.01;L5/S1 left:rho 0.128,P < 0.01;L5/S1 right:rho < 0.157,P < 0.001).CONCLUSION Although MRI is the standard imaging tool for diagnosing lumbar spinal stenosis,this study showed only a weak correlation of LRS on MRI and clinical findings.This can be attributed to a number of reasons outlined in this study,underlining that imaging findings alone are not sufficient to establish a reliable diagnosis for patients with LRS.

Computer-assisted minimally invasive spine surgery for resection of ossification of the ligamentum flavum in the thoracic spine

Background Ossification of the ligamentum flavum （OLF） has been widely recognized as one of the main causes of thoracic spinal canal stenosis and thoracic myelopathy.Decompression is the only effective strategy for treating thoracic myelopathy caused by OLF.The purpose of this study was to describe the clinical outcomes of computer-assisted minimally invasive spine surgery （CAMISS） for posterior decompression in patients with thoracic myelopathy caused by OLF.Methods In all cases,the surgical procedure was performed with the assistance of an intraoperative three-dimensional navigation system.Decompression of the spinal cord was performed with a high-speed drill; the supraspinal ligaments and spinous process were partially preserved.The outcomes were evaluated by a modified Japanese Orthopedic Association （JOA） scoring system and recovery rates.Results The mean duration of follow-up for the 14 cases was 3.9 years.All patients experienced neurological recovery,the mean JOA score improving from 6.1 points preoperatively to 8.6 points at final follow-up and the mean rate of recovery being 52.7% （excellent in two cases,good in eight,fair in three,and unchanged in one）.Conclusion CAMISS is a safe and effective procedure for resection of the OLF in the thoracic spine.