Toru Yokoyama

Axial symptoms after cervical laminoplasty with C3 laminectomy compared with conventional C3-C7 laminoplasty: a modified laminoplasty preserving the semispinalis cervicis inserted into axis.

Study Design. Results of C4–C7 laminoplasty with C3 laminectomy and C3–C7 laminoplasty were compared. Objectives. To clarify prospectively whether the modified laminoplasty preserving the semispinalis cervicis inserted into C2 could reduce the axial symptoms compared with conventional laminoplasty reattaching the muscle to C2. Summary of Background Data. Intraoperative damage of the semispinalis cervicis is relevant to the development of axial symptoms after laminoplasty. In C3–C7 laminoplasty, however, it is difficult to preserve the muscle insertion into C2 while opening the C3 lamina. Methods. The axial symptoms of 40 patients (Group A) with C4–C7 laminoplasty with C3 laminectomy were compared with those of 16 patients (Group B) with C3–C7 laminoplasty. The cross-sectional areas of the cervical posterior muscles were measured on magnetic resonance images. Results. The number of patients with no postoperative axial symptoms increased (P = 0.035) from 19% to 52.5%, and the number of patients whose symptoms worsened after surgery decreased (P = 0.020) from 50% to 17.5%. The average atrophy rate of cross-sectional area was smaller (P < 0.001) in Group A (2.4%) than in Group B (10.8%). Conclusions. This method was less invasive to the cervical posterior muscles than C3–C7 laminoplasty. This is an effective procedure for preventing postoperative axial symptoms.

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.

Radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligament: a multicenter cohort study.

Study Design. A multicenter cohort study was performed retrospectively. Objective. To identify radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligaments (OPLL). Summary of Background Data. The pathomechanism of myelopathy in the OPLL remains unknown. Some patients with large OPLL have not exhibited myelopathy for a long periods of time. Predicting the course of future neurologic deterioration in asyptomatic patients with OPLL is difficult at their initial visit. Methods. A total of 156 OPLL patients from 16 spine institutes with an average of 10.3 years of follow-up were reviewed. Subjects underwent a plain roentgenogram, computed tomography (CT), and magnetic resonance imaging of the cervical spine during the follow-up. The trauma history of the cervical spine, maximum percentage of spinal canal stenosis in a plain roentgenogram and CT, range of motion of the cervical spine, and axial ossified pattern in magnetic resonance imaging or CT were reviewed in relation to the existence of myelopathy. Results. All 39 patients with greater than 60% spinal canal stenosis on the plain roentgenogram exhibited myelopathy. Of 117 patients with less than 60% spinal canal stenosis, 57 (49%) patients exhibited myelopathy. The range of motion of the cervical spine was significantly larger in patients with myelopathy than in those of without it. The axial ossified pattern could be classified into 2 types: a central type and a lateral deviated type. The incidence of myelopathy in patients with less than 60% spinal canal stenosis was significantly higher in the lateral deviated-type group than in the central-type group. Fifteen patients of 156 subjects developed trauma-induced myelopathy. Of the 15 patients, 13 had mixed-type OPLL and 2 had segmental-type OPLL. Conclusion. Static and dynamic factors were related to the development of myelopathy in OPLL.

Adult scoliosis in syringomyelia associated with Chiari I malformation.

Study Design. In adult syringomyelia associated with Chiari I malformation, the spinal deformity, the configuration of cerebellar tonsillar descent, the configuration of syrinx, and the clinical evaluation before and after surgery were investigated. Objectives. To investigate the characteristics of the scoliosis in syringomyelia associated with Chiari I malformation. Summary of Background Data. In previous studies, the clinical characteristics of pediatric scoliosis associated with syringomyelia have been reported. Methods. In this study, 42 patients with syringomyelia were treated. All the patients were 20 years of age or older. They were divided into three groups: Group 1 comprising those without scoliosis, Group 2 composed of those with scoliosis of 10° or more but less than 20°, and Group 3 consisting of those with scoliosis of 20° or more. Investigations conducted with the three groups included determining the curve patterns of scoliosis, the degree of thoracic kyphosis, the configuration of cerebellar tonsillar descent, the configuration of syrinx, the morbidity period, and the clinical evaluation before and after surgery. Results. There were 12 patients in Group 1, 21 patients in Group 2, and 9 patients in Group 3. The concomitant rate of adult syringomyelia with scoliosis was 71.4%. As scoliosis advanced, the kyphotic angle also increased. The concordance in laterality between the cerebellar tonsil and curve convex was 70%. Findings showed that the more advanced the scoliosis was, the more aggravated the neurologic symptoms were, and the poorer the surgical outcomes tended to be. Conclusions. In adult syringomyelia with scoliosis, the morbidity period is long, the syrinx is long, the neurologic symptoms are aggravated, and the surgical outcomes tend to be poor.

A diagnostic support tool for lumbar spinal stenosis: a self-administered, self-reported history questionnaire

BackgroundThere is no validated gold-standard diagnostic support tool for LSS, and therefore an accurate diagnosis depends on clinical assessment. Assessment of the diagnostic value of the history of the patient requires an evaluation of the differences and overlap of symptoms of the radicular and cauda equina types; however, no tool is available for evaluation of the LSS category. We attempted to develop a self-administered, self-reported history questionnaire as a diagnostic support tool for LSS using a clinical epidemiological approach. The aim of the present study was to use this tool to assess the diagnostic value of the history of the patient for categorization of LSS.MethodsThe initial derivation study included 137 patients with LSS and 97 with lumbar disc herniation who successfully recovered following surgical treatment. The LSS patients were categorized into radicular and cauda equina types based on history, physical examinations, and MRI. Predictive factors for overlapping symptoms between the two types and for cauda equina symptoms in LSS were derived by univariate analysis. A self-administered, self-reported history questionnaire (SSHQ) was developed based on these findings. A prospective derivation study was then performed in a series of 115 patients with LSS who completed the SSHQ before surgery. All these patients recovered following surgical treatment. The sensitivity of the SSHQ was calculated and clinical prediction rules for LSS were developed. A validation study was subsequently performed on 250 outpatients who complained of lower back pain with or without leg symptoms. The sensitivity and specificity of the SSHQ were calculated, and the test-retest reliability over two weeks was investigated in 217 patients whose symptoms remained unchanged.ResultsThe key predictive factors for overlapping symptoms between the two categories of LSS were age > 50, lower-extremity pain or numbness, increased pain when walking, increased pain when standing, and relief of symptoms on bending forward (odds ratio ≥ 2, p < 0.05). The key predictive factors for cauda equina type symptoms were numbness around the buttocks, walking almost causes urination, a burning sensation around the buttocks, numbness in the soles of both feet, numbness in both legs, and numbness without pain (odds ratio ≥ 2, p < 0.05). The sensitivity and specificity of the SSHQ were 84% and 78%, respectively, in the validation data set. The area under the receiver operating characteristic curve was 0.797 in the derivation set and 0.782 in the validation data set. In the test-retest analysis, the intraclass correlation coefficient for the first and second tests was 85%.ConclusionA new self-administered, self-reported history questionnaire was developed successfully as a diagnostic support tool for LSS.

Spinal cord shift on magnetic resonance imaging at 24 hours after cervical laminoplasty.

Study Design. A prospective study in 19 patients after cervical laminoplasty, using magnetic resonance imaging. Objective. To evaluate the value of spinal cord shift at 24 hours after cervical laminoplasty. Summary of Background Data. Postoperative C5 palsy is a noticeable complication within 1 week after cervical laminoplasty. The root tethering due to the posterior shift of the spinal cord after laminoplasty was reported as one of the causes of C5 palsy. However, the spinal cord shift after surgery within 1 week is unknown. Methods. The posterior shift of the spinal cord was measured in 19 consecutive patients on magnetic resonance images at 24 hours and 2 weeks after cervical laminoplasty. Results. The mean posterior shift of the spinal cord at 24 hours was 2.8 mm, with the maximum at the C5 level, decreasing to 1.9 mm at 2 weeks. The posterior shift of the spinal cord at C5 was correlated with the amount of the dura mater at C4, C5, and C6 levels. In a patient with right C5 palsy, posterior shift at C5 level was 5.5 mm, decreasing to 3.0 mm at 2 weeks after surgery. The posterior shift of the spinal cord was not correlated with the sagittal alignment. Conclusion. The posterior shift of the spinal cord at 24 hours had a tendency to shift more posteriorly than that observed at 2 weeks after cervical laminoplasty. C5 palsy may be prevented if the expansion of dura mater, which is strongly correlated with the posterior shift, can be controlled.

Anterior cervical fusion using porous hydroxyapatite ceramics for cervical disc herniation. a two-year follow-up.

BACKGROUND CONTEXT The Smith-Robinson Method (SR), which employs autogenous bone, is the current standard for anterior cervical fusion (AF) surgery. However, autogenous bone has graft-related complications and morbidity, and harvesting it increases trauma and risk to the patient. The use of hydroxyapatite ceramic (HAP) inserts may provide a superior alternative. PURPOSE To determine the efficacy of using HAP in AF. STUDY DESIGN/SETTING A retrospective study of patients who had AF surgery with wide decompression and porous HAP inserts used to treat cervical disc herniation (CHD). PATIENT SAMPLE We evaluated 36 patients who had single-level AF using HAP for CHD, without internal fixations, clinically and radiographically with a minimum follow-up of 2 years. There were 25 men and 11 women, with an average age of 49 years (age range, 24-78 years). Preoperative diagnosis included 25 cases with myelopathy and 11 cases with radiculopathy. OUTCOME MEASURES We established four grades to classify the degree of bony fusion between the HAP and vertebra, based on any motion at the fused segment, any radiolucent zones (RZ) between vertebral bodies and the grafted HAP, and anterior or posterior bone formations on grafted HAPs. We evaluated the severity of myelopathy by applying the Japan Orthopaedic Association (JOA) scoring system. We evaluated the surgical outcome of the myelopathy patients using the Hirabayashi recovery rating, and for the radiculopathy patients, we used the Herkowitz criteria. METHODS We retrospectively reviewed the radiographic and clinical records of all 36 patients from surgery up to periods ranging from 2 to 7 years after surgery, with the average period of follow-up being 4.5 years. We systematically classified the degree of bony fusion into four grades ranging from Grade 1 nonunion to Grade 4 complete union. RESULTS None of the subjects showed Grades 1 and 2 fusion. Eleven percent of the cases showed Grade 3 and 89% showed Grade 4. Loss of height of the fused segment was observed in 29 cases with an average of 1.6 mm. A decrease of lordotic angle of the fused segment was observed in six cases with an average of 2.3 degrees. Four cases revealed cracked HAP inserts but achieved Grade 4 bone fusion. There was no evidence of collapse or displacement of HAPs. The results of the 11 radiculopathy patients were excellent in 10 cases and good in the remaining case. The recovery rate of the 25 myelopathy patients was 73.0%. CONCLUSIONS Our method of anterior cervical fusion surgery using porous HAP inserted into resected end plates, combined with a wide decompression procedure, had clinical and radiographic results so satisfactory that we conclude that it can effectively replace the use of autogenous bone for treating cervical disc herniation.

Acute Cervical Spinal Cord Injury Complicated by Preexisting Ossification of the Posterior Longitudinal Ligament : A Multicenter Study

Study Design. Retrospective multicenter study. Objective. To review the clinical characteristics of traumatic cervical spinal cord injury (SCI) associated with ossification of the posterior longitudinal ligament (OPLL). Summary of Background Data. Despite its potentially devastating consequences, there is a lack of information about acute cervical SCI complicated by OPLL. Methods. This study included consecutive patients with acute traumatic cervical SCI (Frankel A, B, and C) who were admitted within 48 hours of injury to 34 spine institutions across Japan. For analysis of neurologic outcome, patients who had completed at least a 6-month follow-up were included. Neurologic improvement was defined as at least one grade conversion in Frankel grade. Results. A total of 453 patients were identified (367 men, 86 women; mean age, 59 years). OPLL was found in 106 (23%) patients (87 men, 19 women; mean age, 66 years). Most of the patients with OPLL (94 of 106) were without bone injury, presenting with incomplete SCI. The prevalence of OPLL reached 34% in SCI without bone injury. The cause of SCI was predominantly falls (74%). Only 25% of the patients were aware of OPLL. Half of the OPLL patients reported gait disturbance before injury. Forty-eight (52%) OPLL patients without bone injury underwent surgery (median, 13.5 days after injury), mostly laminoplasty. Overall, no significant difference was noted in neurologic improvement between surgery group and conservative group. However, further stratification showed that surgery was associated with greater neurologic recovery in patients who had gait disturbance before injury (P = 0.04). Conclusion. Prevalence of OPLL among cervical SCI was alarmingly high, especially in those without bone injury. Most of cervical SCI associated with OPLL were incomplete, without bone injury, and caused predominantly by low-energy trauma. The majority of the patients were unaware of OPLL. Surgery produced better neurologic recovery in patients who had gait disturbance before injury.

Cervical range of motion and alignment after laminoplasty preserving or reattaching the semispinalis cervicis inserted into axis.

Study Design A radiographic study in 111 patients using radiographs was conducted. Objective To clarify whether the modified laminoplasty with C3 laminectomy preserving the semispinalis cervicis (SSC) inserted into C2 could maintain the postopertive range of motion (ROM) and sagittal alignment compared with conventional C3-C7 laminoplasty reattaching the muscle to C2. Summary of Background Data Intraoperative injury of the SSC is relevant to the significant loss of ROM and the malalignment after laminoplasty. To expose the C3 lamina, however, the SSC inserted into C2 could not be preserved in conventional C3-C7 laminoplasty. Methods The ROM and sagittal alignment of 70 patients (group A) (52 men, 18 women, mean age 59 y, mean follow-up period 1 y and 7 mo) with C4-C7 laminoplasty with C3 laminectomy were compared with those of 41 patients (group B) (28 men, 13 women, mean age 59 y, mean follow-up period 2 y and 6 mo) with C3-C7 laminoplasty using radiographs of the cervical spine. Results Regarding C2-C7 ROM, the postoperative ROM was larger (P=0.003) and the decrease rate of ROM was smaller (P=0.0006), and decreased ROM in extension was smaller (P<0.0001) in group A. Regarding O-C2 ROM, the increased ROM was smaller (P=0.043) and increased ROM in extension was smaller (P=0.001) in group A. Regarding O-C7 ROM, the postoperative ROM was larger (P=0.029) in group A. Regarding the cervical alignment, the increased lordotic angle at O-C2 was smaller (P=0.046) in group A. Conclusions This modified laminoplasty preserving the SSC inserted into C2 is an effective procedure for maintaining postoperative ROM, especially in extension, and sagittal alignment of the upper cervical spine well.

Tumour necrosis factor α-stimulated gene-6 inhibits osteoblastic differentiation of human mesenchymal stem cells induced by osteogenic differentiation medium and BMP-2

To better understand the molecular pathogenesis of OPLL (ossification of the posterior longitudinal ligament) of the spine, an ectopic bone formation disease, we performed cDNA microarray analysis on cultured ligament cells from OPLL patients. We found that TSG-6 (tumour necrosis factor alpha-stimulated gene-6) is down-regulated during osteoblastic differentiation. Adenovirus vector-mediated overexpression of TSG-6 inhibited osteoblastic differentiation of human mesenchymal stem cells induced by BMP (bone morphogenetic protein)-2 or OS (osteogenic differentiation medium). TSG-6 suppressed phosphorylation and nuclear accumulation of Smad 1/5 induced by BMP-2, probably by inhibiting binding of the ligand to the receptor, since interaction between TSG-6 and BMP-2 was observed in vitro. TSG-6 has two functional domains, a Link domain (a hyaluronan binding domain) and a CUB domain implicated in protein interaction. The inhibitory effect on osteoblastic differentiation was completely lost with exogenously added Link domain-truncated TSG-6, while partial inhibition was retained by the CUB domain-truncated protein. In addition, the inhibitory action of TSG-6 and the in vitro interaction of TSG-6 with BMP-2 were abolished by the addition of hyaluronan. Thus, TSG-6, identified as a down-regulated gene during osteoblastic differentiation, suppresses osteoblastic differentiation induced by both BMP-2 and OS and is a plausible target for therapeutic intervention in OPLL.