Combined measurement of nerve root blood flow and electrophysiological values: intraoperative straight-leg-raising test for lumbar disc herniation.

STUDY DESIGN: A total of 15 patients with lumbar disc herniation at the L5-S1 disc level who underwent microendoscopic discectomy were examined. The nerve root blood flow and electrophysiological values were measured during an intraoperative straight-leg-raising (SLR) test. OBJECTIVE: To investigate the relationships between nerve root blood flow changes and the electrophysiological values during an intraoperative SLR test. SUMMARY OF THE BACKGROUND DATA: It is unknown how the electrophysiological values are affected by nerve root blood flow changes during an SLR test. METHODS: We measured S1 nerve root blood flow and electrophysiologically evaluated the nerve root using the compound muscle action potentials (CMAPs) from the gastrocnemius muscle after S1 nerve root stimulation during an intraoperative SLR test. Subsequently, we analyzed the relationships between the nerve root blood flow changes and the electrophysiological values. RESULTS: Before discectomy, there were sharp decreases in the nerve root blood flow after 1 and 3 minutes of the SLR test (P < 0.001), and the amplitudes of the CMAPs deteriorated significantly (P < 0.001). Significant correlations were found between the decrease ratio for the nerve root blood flow during the SLR test and the deterioration ratio for the amplitude of the CMAPs. After discectomy, the blood flow increased significantly (P = 0.001). When the SLR test was performed again, the blood flow showed no significant decreases. The average amplitudes of the CMAPs were significantly ameliorated (P < 0.01). When the SLR test was performed again, no significant differences were found for the average amplitudes after 1 and 3 minutes of the test. CONCLUSION: Significant correlations were found between the decrease ratio for the nerve root blood flow and the deterioration ratio for the amplitude of the CMAPs. The present results demonstrate that temporary ischemic changes in the nerve root cause transient conduction disturbances.

Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis.

STUDY DESIGN: The clinical relationship between the local pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. OBJECTIVE: To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. SUMMARY OF BACKGROUND DATA: The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. METHODS: From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the local pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the local pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. RESULTS: The local pressure of the intervertebral foramen significantly increased during lumbar spine extension (P<0.001). The patients who demonstrated large changes in the local pressure between flexion and extension showed a significantly poor walking ability (P=0.003). Moreover, the patients who had 2-level lumbar spinal canal stenosis showed significantly smaller changes in the local pressure between flexion and extension than 1-level lumbar spinal canal stenosis patients (P=0.01). CONCLUSIONS: The present study suggests that the genesis of neurogenic intermittent claudication in lumbar spinal canal stenosis may be greatly affected by the variation of the dynamic mechanical stress on the spinal nerve roots of the lumbar spine, rather than the static mechanical stress on the spinal nerve roots with each posture. Moreover, 2-level lumbar spinal canal stenosis patients demonstrated radicular symptoms with relatively less external stress on their spinal nerve roots in the vertebral foramen than that observed in 1-level lumbar spinal canal stenosis patients.

Surgical results and related factors for ossification of posterior longitudinal ligament of the thoracic spine: a multi-institutional retrospective study.

STUDY DESIGN: Retrospective multi-institutional study OBJECTIVE: To describe the surgical outcomes in patients with ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) and to clarify factors related to the surgical outcomes. SUMMARY OF BACKGROUND DATA: Detailed analyses of surgical outcomes of T-OPLL have been difficult because of the rarity of this disease. METHODS: The subjects were 154 patients with T-OPLL who were surgically treated at 34 institutions between 1998 and 2002. The surgical procedures were laminectomy in 36, laminoplasty in 51, anterior decompression via anterior approach in 25 and via posterior approach in 29, combined anterior and posterior fusion in 8, and sternum splitting approach in 5 patients. Instrumentation was conducted in 52 patients. Assessments were made on (1) The Japanese Orthopedic Association (JOA) scores (full score, 11 points), its recovery rates, (2) factors related to surgical results, and (3) complications and their consequences. RESULTS: (1) The mean JOA score before surgery was 4.6 +/- 2.0 and, 7.1 +/- 2.5 after surgery. The mean recovery rate was 36.8% +/- 47.4%. (2) The recovery rate was 50% or higher in 72 patients (46.8%). Factors significantly related to this were location of the maximum ossification (T1-T4) (odds ratio, 2.43-4.17) and the use of instrumentation (odds ratio, 3.37). (3) The frequent complications were deterioration of myelopathy immediately after surgery in 18 (11.7%) and dural injury in 34 (22.1%) patients. CONCLUSION: The factors significantly associated with favorable surgical results were maximum ossification located at the upper thoracic spine and use of instrumentation. T-OPLL at the nonkyphotic upper thoracic spine can be treated by laminoplasty that is relatively a safe surgical procedure for neural elements. The use of instrumentation allows correction of kyphosis or prevention of progression of kyphosis, thereby, enhancing and maintaining decompression effect, and its use should be considered with posterior decompression.

Measurement of the local pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots in the vertebral foramen.

STUDY DESIGN: The intraoperative findings of the local pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots were evaluated. OBJECTIVE: To investigate the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA: As far as we know, few reports have so far described the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. METHODS: The local pressure of the intervertebral foramen was continuously measured while the lumbar spine posture was changed in 66 vertebral foramens. In addition, 20 L5 nerve roots were electrophysiologically evaluated using the compound muscle action potentials (CMAPs) from tibialis anterior (TA) muscle after L5 nerve root stimulation. RESULTS: The local pressure of the intervertebral foramen was significantly increased during lumbar spine extension (P < 0.001); moreover, the latency and amplitude of the CMAPs both significantly deteriorated in line with the increasing local pressure. CONCLUSIONS: Our findings suggested that a double compression of the nerve root exists in lumbar spinal stenosis with lumbar spine extension, which includes the spinal canal and the vertebral foramen.

The transverse placement laminoplasty using titanium miniplates for the reconstruction of the laminae in thoracic and lumbar lesion.

Laminoplasty for thoracic and lumbar spine surgery enables surgeons to preserve the posterior arch of the spine while preventing invasion of hematoma and scar tissue, postoperative instability, subluxation, and kyphotic deformities. The authors have developed a new surgical technique: namely, transverse placement laminoplasty (TPL) using titanium miniplates. Eight patients and 18 laminae underwent TPL using a titanium mini-plate. The preoperative diagnoses were six intradural tumors, one ossification of a yellow ligament and one spontaneous spinal cord herniation. The mean blood loss was 219 g and the mean duration of surgery was 3 h and 54 min. The mean postoperative follow-up period was 2 years and 1 month. All eight patients started to sit with a soft brace within the second postoperative day, and were able to walk within the fifth postoperative day. There were no cases of spinal deformity, an invasion of hematoma or scar tissue into the spinal canal on magnetic resonance imaging, or back pain. TPL simultaneously enables surgeons to obtain sufficient field of vision and rigid early fixation of the reduced lamina at the time of surgery. Moreover, our novel technique also simplifies the postoperative treatment, while preserving the posterior arch of the spine, and also preventing an invasion of a hematoma and scar tissue, postoperative instability, subluxation, and kyphotic deformities.

Combined bone morphogenetic protein-2 and -7 gene transfer enhances osteoblastic differentiation and spine fusion in a rodent model.

UNLABELLED: To enhance the osteogenic activity of BMP, combination BMP2 and BMP7 gene transfer was performed. This approach led to a significant increase in osteoblastic differentiation of mesenchymal precursors compared with single BMP gene transfer in vitro. When tested in 78 rats, combination gene transfer enhanced mechanically stable spine fusion and bone formation rate versus single BMP gene transfer. INTRODUCTION: Although clinical bone morphogenetic protein (BMP) therapy is effective, required doses are very high. Previous studies have suggested that the co-expression of two different BMP genes can result in the production of heterodimeric BMPs that may be more potent than homodimers. In this study, combined BMP2 and BMP7 gene transfer was performed to test whether this approach improves osteoblastic differentiation and bone formation compared with single BMP gene transfer. MATERIALS AND METHODS: A producer cell (A549) was co-transfected with adenovirus vectors encoding BMP2 (AdBMP2) and BMP7 (AdBMP7) or, as controls, each vector alone, AdNull (with no transgene) or no virus. Supernatants were compared for their ability to stimulate osteoblastic differentiation of C2C12 myoblasts and MC3T3-E1 pre-osteoblasts. In a rat posterolateral spine fusion model, co-administration of AdBMP2 and AdBMP7 was compared with treatment with each vector alone, AdNull or no virus in 78 rats. The spines were assessed 8 weeks after surgery for radiographic and mechanical fusion, bone formation, and mineralization. RESULTS: BMP2 and BMP7 were co-precipitated from supernatants of cells co-transfected with AdBMP2 and AdBMP7, indicating the presence of BMP2/7 heterodimer. Supernatants of co-transfected cells containing relatively low doses (7-140 ng/ml) of BMPs induced osteocalcin expression and alkaline phosphatase activity in both C2C12 and MC3T3-E1 cells, that were up to 6- and 40-fold higher, respectively, than levels induced by maximal doses (200-1000 ng/ml) of either BMP2 or BMP7 alone. In the spine fusion model, co-administration of AdBMP2 and AdBMP7 resulted in a significantly greater number of mechanically stable fusions and also 2-fold higher mineralization rate and bone volume in the fusion mass versus single BMP gene transfer (p < 0.02, all comparisons). CONCLUSION: Combined BMP2 and BMP7 gene transfer is significantly more effective in inducing osteoblastic differentiation and spine fusion than individual BMP gene transfer.