Toshihiko Taguchi

The prevalence and impact of chronic neuropathic pain on daily and social life: A nationwide study in a Japanese population

This study marks the first epidemiological evaluation of the prevalence and burden of chronic neuropathic pain (NeP) in an Asian population. The objective of this nationwide cross‐sectional study was to identify the characteristics of individuals with NeP, detect the NeP features that affect their quality of life (QOL), and demonstrate the negative effects of NeP on social and daily living as well as comorbidities including depression, anxiety and sleep disorders.

Cervical ossification of the posterior longitudinal ligament: factors affecting the effect of posterior decompression

Objective: Decompression procedures for cervical myelopathy of ossification of the posterior longitudinal ligament (OPLL) are anterior decompression with fusion, laminoplasty, and posterior decompression with fusion. Preoperative and postoperative stress analyses were performed for compression from hill-shaped cervical OPLL using 3-dimensional finite element method (FEM) spinal cord models. Methods: Three FEM models of vertebral arch, OPLL, and spinal cord were used to develop preoperative compression models of the spinal cord to which 10%, 20%, and 30% compression was applied; a posterior compression with fusion model of the posteriorly shifted vertebral arch; an advanced kyphosis model following posterior decompression with the spinal cord stretched in the kyphotic direction; and a combined model of advanced kyphosis following posterior decompression and intervertebral mobility. The combined model had discontinuity in the middle of OPLL, assuming the presence of residual intervertebral mobility at the level of maximum cord compression, and the spinal cord was mobile according to flexion of vertebral bodies by 5°, 10°, and 15°. Results: In the preoperative compression model, intraspinal stress increased as compression increased. In the posterior decompression with fusion model, intraspinal stress decreased, but partially persisted under 30% compression. In the advanced kyphosis model, intraspinal stress increased again. As anterior compression was higher, the stress increased more. In the advanced kyphosis  + intervertebral mobility model, intraspinal stress increased more than in the only advanced kyphosis model following decompression. Intraspinal stress increased more as intervertebral mobility increased. Conclusion: In high residual compression or instability after posterior decompression, anterior decompression with fusion or posterior decompression with instrumented fusion should be considered.

Finite element analysis of compression fractures at the thoracolumbar junction using models constructed from medical images

Vertebral fractures commonly occur at the thoracolumbar junction. These fractures can be treated with mild residual deformity in many cases, but are reportedly associated with increased risk of secondary vertebral fractures. In the present study, a three-dimensional (3D) whole spine model was constructed using the finite element method to explore the mechanism of development of compression fractures. The 3D model of the whole spine, from the cervical spine to the pelvis, was constructed from computed tomography (CT) images of an adult male. Using a normal spine model and spine models with compression fractures at the T11, T12 or L1 vertebrae, the distribution of strain was analyzed in the vertebrae after load application. The normal spine model demonstrated greater strain around the thoracolumbar junction and the middle thoracic spine, while the compression fracture models indicated focused strain at the fracture site and adjacent vertebrae. Increased load time resulted in the extension of the strain region up to the middle thoracic spine. The present findings, that secondary vertebral fractures commonly occur around the fracture site, and may also affect the thoracic vertebrae, are consistent with previous clinical and experimental results. These results suggest that follow-up examinations of compression fractures at the thoracolumbar junction should include the thoracic spine and adjacent vertebrae. The current data also demonstrate that models created from CT images can be used for various analyses.

Diffuse Pigmented Villonodular Synovitis Around the Ankle

BACKGROUND Pigmented villonodular synovitis (PVNS) is a rare disorder around the ankle joint. The optimal treatment for diffuse-type PVNS is still controversial because of the high incidence of recurrence. We present the clinical features of our patients and review the current diagnostic and treatment modalities. METHODS Five patients with PVNS located around the ankle were surgically treated. In three patients, diffuse PVNS arose from the ankle joint, and in the other two it arose from the calcaneocuboid and intercuneiform joints. The average follow-up time after surgery was 2.9 years (range, 2-4.6 years). RESULTS The average time between onset of pain and diagnosis of PVNS was 6.4 years (range, 4-10 years). Arthrotomic tumor resection was performed in all of the patients. In the three patients with ankle joint PVNS, both medial and lateral approaches were used. One patient experienced mild infection at the surgical site, but this healed conservatively. No tumor recurrences had occurred after minimum follow-up of 2 years, although mild pain persisted in the three patients with ankle PVNS. CONCLUSIONS Diagnosis of diffuse PVNS is frequently delayed due to vague symptoms and variable growth patterns. Orthopedic clinicians should be aware of the existence of this lesion, and it should be suspected in patients with persistent ankle swelling. To prevent tumor recurrence, accurate evaluation of tumor location and careful operative planning are mandatory. A combined surgical approach involving medial and lateral incision is necessary to expose the entire joint cavity.

Utility of the central motor conduction time recorded from the abductor pollicis brevis and the abductor digiti minimi muscles in patients with C6–7 myelopathy

Objective: Central motor conduction time (CMCT) recorded from the abductor pollicis brevis (CMCT-APB) and abductor digiti minimi (CMCT-ADM) muscles may enable the evaluation of patients with C6–7 myelopathy. CMCT is more useful for the evaluation of the function of spinal cord than magnetic resonance imaging (MRI) findings. CMCT may be associated with age and height. However, there are few reports regarding CMCT-APB in normal subjects. This study aimed to investigate the relationships between age, height, and conduction parameters in normal subjects to assess the effectiveness of using CMCT-APB and CMCT-ADM for the evaluation of patients with C6–7 and C7–T1 myelopathy. Design: Retrospective study. Methods: Fifteen patients with cervical compressive myelopathy at C6–7 (11 patients) or C7-T1 (4 patients) level were enrolled. The control group consisted of 150 normal subjects (mean age 45.8±17.0 years; mean height 163.6±8.9 cm). Motor evoked potentials induced by transcranial magnetic stimulation and F-waves were used to determine CMCT. Outcome measures: CMCT-APB, CMCT-ADM. Results: The normative values of CMCT-APB and CMCT-ADM were 5.3±0.7 ms and 5.2±0.8 ms, respectively. CMCT-APB was significantly longer than CMCT-ADM for patients with C6–7 myelopathy (P < 0.05). Neither of the CMCTs for those with C7–T1 myelopathy were significantly different from those of controls, but CMCT-APB was more prolonged than CMCT-ADM in patients with C6–C7 myelopathy. Conclusions: CMCTs improve the accuracy of the diagnosis of myelopathy by pinpointing the lesion in combination with MRI imaging. Selective CMCT-APB prolongation may be seen in patients with C6–7 myelopathy but not C7-T1 myelopathy.

Age‑related changes of the spinal cord: A biomechanical study

Although it is known that aging plays an important role in the incidence and progression of cervical spondylotic myelopathy (CSM), the underlying mechanism is unclear. Studies that used fresh bovine cervical spinal cord report the gray matter of the cervical spinal cord as being more rigid and fragile than the white matter. However, there are no reports regarding the association between aging an tensile and Finite Element Method (FEM). Therefore, FEM was used based on the data pertaining to the mechanical features of older bovine cervical spinal cord to explain the pathogenesis of CSM in elderly patients. Tensile tests were conducted for white and gray matter separately in young and old bovine cervical spinal cords, and compared with their respective mechanical features. Based on the data obtained, FEM analysis was further performed, which included static and dynamic factors to describe the internal stress distribution changes of the spinal cord. These results demonstrated that the mechanical strength of young bovine spinal cords is different from that of old bovine spinal cords. The gray matter of the older spinal cord was significantly softer and more resistant to rupture compared with that of younger spinal cords (P<0.05). Among the old, although the gray matter was more fragile than the white matter, it was similar to the white matter in terms of its rigidity (P<0.05). The in vitro data were subjected to three compression patterns. The FEM analysis demonstrated that the stress level rises higher in the old spinal cords in response to similar compression, when compared with young spinal cords. These results demonstrate that in analyzing the response of the spinal cord to compression, the age of patients is an important factor to be considered, in addition to the degree of compression, compression speed and parts of the spinal cord compression factor.

Biomechanical Study of Cervical Posterior Decompression

Study Design Biomechanical study. Purpose We examined the dynamic characteristics of different operative procedures using three-dimensional finite-element models. Overview of Literature Cervical laminoplasty is often selected for patients requiring multilevel spinal decompression. Many laminoplasty techniques have been developed and are continually being improved. Methods Images were extracted for the two intervertebral joints between C3 and C5 in domestic rabbits. The following models were created: preoperative, laminectomy, Z-plasty, open door laminoplasty, French open door laminoplasty, en-bloc laminoplasty, and double-door laminoplasty. The loads required for sagittal rotation of 2.5°, 5°, and 7.5° were measured in vitro and respectively placed at the bottom of the C5 model. Displacement of the plate in the X, Y, and Z coordinates was measured and the rotational angles of the plate were determined. Results The sagittal rotation angle was greater in the laminectomy model than in the preoperative model, but was almost the same in the preoperative and Z-plasty models. Compared with the preoperative model, sagittal rotation angles were smaller in the French open door, open door, en-bloc, and double-door laminoplasty models. Conclusions Laminectomy and various types of laminoplasty are associated with different mechanical features, such as stability and mobility, allowing for selection of the most appropriate surgical procedure for each case.

Surgical and general complications in 2,961 Japanese patients with cervical spondylotic myelopathy: Comparison of different age groups

Introduction: Details of surgical and general complications for patients with cervical spondylotic myelopathy (CSM) are still uncertain. The purpose of this study was to describe surgeries and their complications among Japanese patients with CSM. Methods: The Japanese Society for Spine Surgery and Related Research performed a nationwide survey on spine surgery and complications in 2011. Data of patients with 2,961 CSM >40 years old were included. The clinicopathological variables were basic demographic and clinical information, surgical information, and surgical and general complications. To examine the influence of age, variables were compared among three age groups: patients 40-64 (n=1,123), 65-74 (n=966), and ≥75 (n=872) years of age. Results: The study included 1,970 males and 991 females and the mean age was 64.3 years old. There were 168 anterior (5.7%) and 2,770 posterior (94.2%) approach surgeries. The vast majority of patients with CSM were treated using the posterior approach, 89.4% of whom had decompression surgery only. Anterior surgeries were more common in the younger age group, but posterior surgeries were equally distributed. The incidence of total complications including surgical/general complications was similar for the anterior (16/168; 9.5%) and posterior (295/2,770; 10.6%) approaches. No patient died on the operating table, but four patients (0.1%) died within one month after surgery. No association was detected between complications and age, comorbidity, and other surgical factors. The incidence of complications was similar for the different age groups. However general complications were predominantly observed in the older group and those who had instrumented surgery. Conclusions: The results indicate that the indication and surgical performance for patients with CSM is favorable in Japan, despite the super-aging population. Few serious complications were reported in this study. However, more detailed informed consent about surgical and, in particular, general complications is necessary for the older patients with CSM.

Operative methods for delayed paralysis after osteoporotic vertebral fracture

Purpose: How to select operative methods for delayed paralysis after osteoporotic vertebral fracture remains a matter of debate. It is unclear which procedure provides better neurological and functional recovery. This study aimed to compare the various operative methods and investigate postoperative outcomes. Methods: The study included 42 delayed paralysis patients (mean age 73.7 years). The operative methods were posterior spinal shortening osteotomy with direct decompression and short or long fusion and posterior laminectomy and short fusion with vertebroplasty. All patients in the vertebroplasty group were fitted with hooks to prevent correction loss. We investigated postoperative complications, surgery time, intraoperative blood loss, and changes in walking ability and local kyphotic angle (LKA). Patients were divided into three groups: shortening with a peripheral fusion range of one intervertebral level (the SS group, n = 18), the same procedure with a peripheral fusion range of ≥2 intervertebral levels (the SL group, n = 12), and posterior laminectomy and short fusion with vertebroplasty (the VP group, n = 12). Results: Postoperative complications were observed in five patients, all of whom were in the SS and SL group. There were no significant differences between the SS and SL groups. The VP group experienced significantly shorter mean surgery times, significantly lower mean intraoperative blood loss, and an improvement in paralysis, walking ability, LKA, and correction loss. Overall, the VP group had significantly better outcomes. Conclusion: Posterior laminectomy and short fusion with vertebroplasty with the addition of hooks is useful in cases of delayed paralysis in elderly patients.

Cauda Equina Conduction Time Determined by F-Waves in Normal Subjects and Patients With Neurogenic Intermittent Claudication Caused by Lumbar Spinal Stenosis

Purpose: Lumbar spinal stenosis typically presents with neurogenic intermittent claudication. The aim of this study was to investigate cauda equina conduction time (CECT) in patients with neurogenic intermittent claudication caused by lumbar spinal stenosis and its relationship with age and body height in normal subjects. Methods: The study included 172 normal subjects (group C) (mean age 44.1 ± 16.6 years; mean height 163.7 ± 8.9 cm). Forty-seven patients (group L) (mean age 71.3 ± 8.7 years; mean height 158.8 ± 11.2 cm) underwent surgery because of neurogenic intermittent claudication in cauda equina type of lumbar spinal stenosis. Motor-evoked potentials from the abductor hallucis were recorded. Magnetic stimulation was delivered at the S1 spinous process. Compound muscle action potentials (CMAPs) and F-waves were also recorded after supramaximal electric stimulation of tibial nerves. The peripheral motor conduction time (PMCT) was calculated from the latencies of CMAPs and F-waves as follows: (CMAPs + F-waves − 1)/2. The CECT was calculated by subtracting the onset latency of the motor-evoked potentials from PMCT. Results: The mean values for F-wave latencies, motor-evoked potential latencies, and CECT were 44.5 ± 3.3, 20.6 ± 1.8, and 3.4 ± 0.8 milliseconds, respectively. F-wave and motor-evoked potential latencies showed significant positive linear correlations with age and body height. However, no significant correlation was found between CECT and age (P = 0.43) or body height (P = 0.26). Mean CECT was 5.7 ± 1.5 in group L. There was a significant difference between groups C and L (P < 0.05). Conclusions: The CECT value of normal subjects was 3.4 ± 0.8 milliseconds regardless of age and body height. We suggest that CECT may be a useful factor to consider when evaluating patients with neurogenic intermittent claudication.