Tsukasa Kanchiku

Vascularized fibular graft after excision of giant cell tumor of the distal radius. A case report.

Although hemiarthroplasty of the wrist using vascularized proximal fibula has been described often, long term results with documentation of results are insufficient. A case of giant cell tumor of the distal radius with remarkable extraskeletal extension is reported. Vascularized fibula including its proximal head was used to replace the defect created after en bloc resection of the tumor. There was no deterioration in radiographic findings or function of the new joint at the time of the 10-year followup. Satisfactory range of motion of the wrist and the forearm was maintained. There was no instability in the joint, and grip strength measured 65% of the opposite side. Postoperative magnetic resonance imaging showed survival of the whole graft, including the subchondral portion. In addition to thorough revascularization of the graft, appropriate soft tissue reconstruction using dynamic tendon transfer contributed to the success. When these requirements are fulfilled, the graft can provide a functional and durable result. Although this is a single experience, the authors recommend wrist arthroplasty, rather than arthrodesis, in carefully selected patients.

A genome-wide association study identifies susceptibility loci for ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a common spinal disorder among the elderly that causes myelopathy and radiculopathy. To identify genetic factors for OPLL, we performed a genome-wide association study (GWAS) in ∼8,000 individuals followed by a replication study using an additional ∼7,000 individuals. We identified six susceptibility loci for OPLL: 20p12.3 (rs2423294: P = 1.10 × 10−13), 8q23.1 (rs374810: P = 1.88 × 10−13), 12p11.22 (rs1979679: P = 4.34 × 10−12), 12p12.2 (rs11045000: P = 2.95 × 10−11), 8q23.3 (rs13279799: P = 1.28 × 10−10) and 6p21.1 (rs927485: P = 9.40 × 10−9). Analyses of gene expression in and around the loci suggested that several genes are involved in OPLL etiology through membranous and/or endochondral ossification processes. Our results bring new insight to the etiology of OPLL.

A correlation between magnetic resonance imaging and electrophysiological findings in cervical spondylotic myelopathy.

Study Design. Correlation between compressed spinal cords on magnetic resonance imaging (MRI) and electrophysiological findings in cervical spondylotic myelopathy patients. Objective. To clarify the correlation between spinal-cord-evoked potentials and MRI measurements of compressed spinal cords in patients with cervical spondylotic myelopathy. Summary of Background Data. Compression of the spinal cord does not always cause clinical symptoms and it is difficult to infer the degree of dysfunction of the spinal cord from MRI findings. Methods. Seventeen patients with cervical spondylotic myelopathy were examined with MRI and spinal-cord-evoked potentials before surgery. Using abnormality in spinal-cord-evoked potentials as indicators of spinal cord morphology, spinal-cord transverse area and compression ratios (central and 1/4-lateral) were measured on T1-weighted axial imaging. The correlations between these dimensions and electrophysiological findings were investigated. Results. The mean preoperative transverse area of the spinal cord was 47.13 mm2.The mean preoperative central compression ratio of the spinal cord was 34.4%. The mean preoperative 1/4-lateral compression ratio of the spinal cord was 27.5%. A correlation (Spearman r=0.65, P < 0.01) was observed between the 1/4-lateral compression ratio of the spinal cord and the amplitude ratio of spinal-cord-evoked potentials after electric stimulation of the brain (Br(E)-SCEPs). Conclusions. The preoperative 1/4-lateral compression ratio of the spinal cord was found to reflect the degree of dysfunction of the corticospinal tracts.

S3-4. New alarm point of transcranial electrical stimulation motor evoked potentials for intraoperative spinal cord monitoring. A prospective multicenter study of the Spinal Cord Monitoring Working Group of the Japanese Society for Spine Surgery and Related Research (JSSR)

Transcranial electrical stimulation motor evoked potentials (TcMEPs) became the gold standard for intraoperative spinal cord monitoring. However there is no definite alarm point of TcMEPs due to a lack of multicenter study. Thus we set 70% decrease of amplitude as the alarm point of TcMEPs from the experience of our 48 true positive cases from 2007 to 2009. 959 cases of spinal deformity, spinal cord tumor and ossification of the posterior longitudinal ligament (OPLL) were included in this prospective multicenter study from our 18 institutes related to the Japanese Society for Spine Surgery and Related Research monitoring working group from 2010 to 2012. There were only two false negative cases which were intramedullary spinal cord tumor. This new alarm criterion provided higher sensitivity (95%) and specificity (91.1%) for intraoperative spinal cord monitoring and good accuracy except for intramedullary spinal cord tumor. This study is the first prospective multicenter research to investigate the alarm point of TcMEPs. We recommend the alarm point to be a 70% decrease of amplitude for routine spinal cord monitoring, especially in surgery for spinal deformity, OPLL and extramedullary spinal cord tumor.

Neuromuscular stimulation therapy after incomplete spinal cord injury promotes recovery of interlimb coordination during locomotion.

The mechanisms underlying the effects of neuromuscular electrical stimulation (NMES) induced repetitive limb movement therapy after incomplete spinal cord injury (iSCI) are unknown. This study establishes the capability of using therapeutic NMES in rodents with iSCI and evaluates its ability to promote recovery of interlimb control during locomotion. Ten adult female Long Evans rats received thoracic spinal contusion injuries (T9; 156 +/- 9.52 Kdyne). 7 days post-recovery, 6/10 animals received NMES therapy for 15 min/day for 5 days, via electrodes implanted bilaterally into hip flexors and extensors. Six intact animals served as controls. Motor function was evaluated using the BBB locomotor scale for the first 6 days and on 14th day post-injury. 3D kinematic analysis of treadmill walking was performed on day 14 post-injury. Rodents receiving NMES therapy exhibited improved interlimb coordination in control of the hip joint, which was the specific NMES target. Symmetry indices improved significantly in the therapy group. Additionally, injured rodents receiving therapy more consistently displayed a high percentage of 1:1 coordinated steps, and more consistently achieved proper hindlimb touchdown timing. These results suggest that NMES techniques could provide an effective therapeutic tool for neuromotor treatment following iSCI.

Biomechanical study of the effect of degree of static compression of the spinal cord in ossification of the posterior longitudinal ligament.

OBJECT The authors evaluated the biomechanical effect of 3 different degrees of static compression in a model of the spinal cord in order to investigate the effect of cord compression in patients with ossification of the posterior longitudinal ligament (OPLL). METHODS A 3D finite element spinal cord model consisting of gray matter, white matter, and pia mater was established. As a simulation of OPLL-induced compression, a rigid plate compressed the anterior surface of the cord. The degrees of compression were 10, 20, and 40% of the anteroposterior (AP) diameter of the cord. The cord was supported from behind by the rigid body along its the posterior border, simulating the lamina. Stress distributions inside of the cord were evaluated. RESULTS The stresses on the cord were very low under 10% compression. At 20% compression, the stresses on the cord increased very slightly. At 40% compression, the stresses on the cord became much higher than with 20% compression, and high stress distributions were observed in gray matter and the lateral and posterior funiculus. The stresses on the compressed layers were much higher than those on the uncompressed layer. CONCLUSIONS The stress distributions at 10 and 20% compression of the AP diameter of the spinal cord were very low. The stress distribution at 40% compression was much higher. The authors conclude that a critical point may exist between 20 and 40% compression of the AP diameter of the cord such that when the degree of the compression exceeds this point, the stress distribution becomes much higher, and that this may contribute to myelopathy.

A new rabbit model for the study on cervical compressive myelopathy.

Development process and pathology of myelopathy due to chronic spinal cord compression have not been fully elucidated. This study was conducted in order to establish an experimental model which can efficiently produce myelopathy and be useful in the studies on myelopathy due to chronic spinal cord compression. Under electrophysiological monitoring of the spinal cord, anterior compression was produced on C5 using a plastic screw. Two weeks later, a plastic plate was inserted under the C5 arch. For the subsequent 10 months on average, walking pattern and MR images were periodically monitored. Before the sacrifice, electro‐physiological test was performed and then histopathological examination was done. Palsy appeared at 5 months on average after the addition of posterior compression. Mean compression ratio of the spinal cord calculated on MR images was 34%. All animals with compression showed a high intramedullary signal intensity, and the mean contrast‐to‐noise ratio (CNR) in the compressed area was 49%. Electrophysiological test showed a significant decrease in the amplitude of spinal cord evoked potentials (SCEPs) at the given compression level. Histology showed flattening of the anterior horn, disappearance and necrosis of anterior horn cells in the gray matter; and demyelination and axonal degeneration in the white matter. The antero‐posterior compression produces the condition of spinal canal stenosis. Repeated antero‐posterior compression to the spinal cord is important in establishing myelopathy. The present animal model was evaluated to be useful in the studies on myelopathy.

Dynamic contrast-enhanced magnetic resonance imaging of osteoporotic vertebral fracture.

Study Design. This was a retrospective study of the relation between the blood perfusion of bone marrow in injured vertebrae and the degree of subsequent vertebral collapse in patients with osteoporotic vertebral fractures. Objective. The objective was to evaluate blood perfusion of bone marrow in injured vertebrae using dynamic magnetic resonance imaging and study the possibility of predicting the progression of vertebral collapse. Summary of Background Data. Avascular necrosis of the vertebra is considered to be a cause of delayed vertebral collapse following osteoporotic vertebral fractures, but studies on the relation with the degree of progression of vertebral collapse by evaluation of vertebral blood perfusion have not been reported. Methods. The subjects were 15 vertebrae in 14 patients with osteoporotic vertebral fractures, including 11 women and three men with a median age of 79 years. All patients underwent dynamic magnetic resonance imaging soon after the fracture and the area rate of the noncontrast region of the injured vertebrae in dynamic magnetic resonance imaging was measured. The correlationof pre with the degree of progression of vertebral collapse obtained from plain radiograph imaging was studied. Results. The vertebral collapse rate (percentage loss in vertebral body height) on initial examination was 17 ± 10% (mean ± SD) and that at the final examination was 33 ± 19%, showing a progression of 16 ± 11%. The noncontrast area rate in dynamic magnetic resonance imaging was 18 ± 12%. A significant correlation was found between the degree of progression of vertebral collapse and the noncontrast area rate (Spearman r = 0.97, P < 0.001). Conclusions. The subsequent progression of vertebral collapse tended to increase the greater the noncontrast area in the injured vertebrae in dynamic magnetic resonance imaging. Dynamic magnetic resonance imaging appears to be useful in predicting the progression of collapse of fractured vertebrae.

Anti-interleukin-6 receptor antibody reduces neuropathic pain following spinal cord injury in mice

The present study reports the beneficial effects of an anti-mouse interleukin-6 (IL-6) receptor antibody (MR16-1) on neuropathic pain in mice with spinal cord injury (SCI). Following laminectomy, contusion SCI models were produced using an Infinite Horizon (IH)-impactor. MR16-1 was continuously injected for 14 days using Alzet osmotic pumps. A mouse IL-6 ELISA kit was then used to analyze IL-6 levels in the spinal cord tissue between 12 and 72 h after injury. Motor and sensory functions were evaluated each week using the Basso Mouse Scale (BMS), plantar von Frey and thermal threshold tests. Histological examinations were performed 42 days after SCI. Between 24 and 72 h after SCI, the expression levels of IL-6 were significantly decreased in the MR16-1 treated group. Six weeks after surgery, the BMS score of the MR16-1-treated group indicated significant recovery of neurological functions. MR16-1-treated mice in the SCI group exhibited lower paw withdrawal thresholds in the plantar von Frey and thermal tests, which were used to evaluate allodynia. MR16-1 treatment significantly increased the area of Luxol fast blue-stained tissue, representing spared myelin sheaths. These results indicate that the continuous inhibition of IL-6 signaling by MR16-1 between the early and sub-acute phases following SCI leads to neurological recovery and the suppression of hyperalgesia and allodynia. Overall, our data suggest that the inhibition of severe inflammation may be a promising neuroprotective approach to limit secondary injury following SCI and that an anti-IL-6 receptor antibody may have clinical potential for the treatment of SCI.

Flexion Model Simulating Spinal Cord Injury Without Radiographic Abnormality in Patients With Ossification of the Longitudinal Ligament: The Influence of Flexion Speed on the Cervical Spine

Abstract Background/Objective: It is suspected that the speed of the motion of the spinal cord under static compression may be the cause of spinal cord injury (SCI). However, little is known about the relationship between the speed of the motion of the spinal cord and its stress distributions. The objective was to carry out a biomechanical study of SCI in patients with ossification of the longitudinal ligament without radiologic evidence of injury. Methods: A 3-dimensional finite element spinal cord model was established. After the application of static compression, the model underwent anterior flexion to simulate SCI in ossification of the longitudinal ligament patients without radiologic abnormality. Flexion of the spine was assumed to occur at 1 motor segment. Flexion angle was 5°, and flexion speeds were 0.5°/s, 5°/s, and 50°/s. Stress distributions inside of the spinal cord were evaluated. Results: Stresses on the spinal cord increased slightly after the application of 5° of flexion at a speed of 0.5°/s. Stresses became much higher at a speed of 5°/s and increased further at 50°s. Conclusions: The stress distribution of the spinal cord under static compression increased with faster flexion speed of the spinal cord. High-speed motion of the spinal cord under static compression may be one of the causes of SCI in the absence of radiologic abnormality.