Published papers

Background: The purpose of this study was to test the hypothesis that direct vertebral derotation by pedicle screws (PS) causes hypokyphosis of the thoracic spine in adolescent idiopathic scoliosis (AIS) patients, using computer simulation. Methods: Twenty AIS patients with Lenke type 1 or 2 who underwent posterior correction surgeries using PS were included in this study. Simulated corrections of each patients scoliosis, as determined by the preoperative CT scan data, were performed on segmented 3D models of the whole spine. Two types of simulated extreme correction were performed: 1) complete coronal correction only (C method) and 2) complete coronal correction with complete derotation of vertebral bodies (C + D method). The kyphosis angle (T5-T12) and vertebral rotation angle at the apex were measured before and after the simulated corrections. Results: The mean kyphosis angle after the C + D method was significantly smaller than that after the C method (2.7 ± 10.0° vs. 15.0 ± 7.1°, p<0.01). The mean preoperative apical rotation angle of 15.2 ± 5.5° was completely corrected after the C + D method (0°) and was unchanged after the C method (17.6 ± 4.2°). Conclusions: In the 3D simulation study, kyphosis was reduced after complete correction of the coronal and rotational deformity, but it was maintained after the coronal-only correction. These results proved the hypothesis that the vertebral derotation obtained by PS causes hypokyphosis of the thoracic spine. © 2012 Watanabe et al. licensee BioMed Central Ltd.

Conventional magnetic resonance imaging (MRI) can detect hemorrhage, edema, syrinx, and spinal cord atrophy, but not axonal disruption after spinal cord injury (SCI). We previously demonstrated that diffusion tensor tractography (DTT) could depict axonal disruption after hemisection SCI in common marmosets. In the present study, to determine the relationship between DTT results and functional recovery after contusive SCI, we performed longitudinal DTT, behavioral, and histological analyses before and after contusive SCI in common marmosets. By comparing the tract fiber estimate depicted by DTT with neuronal fibers labeled with RT97 and SMI-31, anti-neurofilament antibodies, we determined the optimal fractional anisotropy (FA) threshold for fiber tracking to be 0.40. The ratio of the number of tract fiber estimates at the lesion site to the number before SCI, determined by DTT, was significantly correlated with the functional recovery after SCI. Moreover, comparison of the longitudinal pre- and post-SCI FA and axial diffusivity (λ||) values revealed that they decreased after injury at the sites caudal to the lesion epicenter in the corticospinal tract and rostral to the lesion epicenter in the dorsal column. The FA values, then, showed partial recovery in the dorsal column. FA-value-oriented color DTT was used to represent axonal sparing or regeneration of the different tracts. These findings indicated that DTT analysis might be a versatile non-invasive tool for evaluating the axonal disruption after SCI. © 2012 Elsevier Inc.

Murine and human iPSC-NS/PCs (induced pluripotent stem cell-derived neural stem/progenitor cells) promote functional recovery following transplantation into the injured spinal cord in rodents. However, for clinical applicability, it is critical to obtain proof of the concept regarding the efficacy of grafted human iPSC-NS/PCs (hiPSC-NS/PCs) for the repair of spinal cord injury (SCI) in a non-human primate model. This study used a pre-evaluated "safe" hiPSC-NS/PC clone and an adult common marmoset (Callithrix jacchus) model of contusive SCI. SCI was induced at the fifth cervical level (C5), followed by transplantation of hiPSC-NS/PCs at 9 days after injury. Behavioral analyses were performed from the time of the initial injury until 12 weeks after SCI. Grafted hiPSC-NS/PCs survived and differentiated into all three neural lineages. Furthermore, transplantation of hiPSC-NS/PCs enhanced axonal sparing/regrowth and angiogenesis, and prevented the demyelination after SCI compared with that in vehicle control animals. Notably, no tumor formation occurred for at least 12 weeks after transplantation. Quantitative RT-PCR showed that mRNA expression levels of human neurotrophic factors were significantly higher in cultured hiPSC-NS/PCs than in human dermal fibroblasts (hDFs). Finally, behavioral tests showed that hiPSC-NS/PCs promoted functional recovery after SCI in the common marmoset. Taken together, these results indicate that pre-evaluated safe hiPSC-NS/PCs are a potential source of cells for the treatment of SCI in the clinic. © 2012 Kobayashi et al.

The paranodal junction is a specialized axon-glia contact zone that is important for normal neuronal activity and behavioral locomotor function in the central nervous system (CNS). Histological examination has been the only method for detecting pathological paranodal junction conditions. Recently, diffusion tensor MRI (DTI) has been used to detect microstructural changes in various CNS diseases. This study was conducted to determine whether MRI and DTI could detect structural changes in the paranodal junctions of the spinal cord in cerebroside sulfotransferase knock-out (CST-KO) mice. Here, we showed that high-resolution MRI and DTI characteristics can reflect paranodal junction failure in CST-KO mice. We found significantly lower T1 times and significantly higher T2 times in the spinal cord MRIs of CST-KO mice as compared to wild-type (WT) mice. Spinal cord DTI showed significantly lower axial diffusivity and significantly higher radial diffusivity in CST-KO mice as compared to WT mice. In contrast, the histological differences in the paranodal junctions of WT and CST-KO mice were so subtle that electron microscopy or immunohistological analyses were necessary to detect them. We also measured gait disturbance in the CST-KO mice, and determined the conduction latency by electrophysiology. These findings demonstrate the potential of using MRI and DTI to evaluate white matter disorders that involve paranodal junction failure. © 2012 Takano et al.

Objective: Systemic steroid injections are used to treat idiopathic sudden-onset sensorineural hearing loss (ISSHL) and some inner ear disorders. Recent studies show that transtympanic (TT) steroid injections are effective for treating ISSHL. As in vivo monitoring of drug delivery dynamics for inner ear is lacking, its time course and dispersion of drugs is unknown. Here, we used a new in vivo imaging system to monitor drug delivery in live mice and to compare drug concentrations over time after TT and systemic injections. Methods: Luciferin delivered into the inner ears of GFAP-Luc transgenic mice reacted with luciferase in GFAP-expressing cells in the cochlear spiral ganglion, resulting in photon bioluminescence. We used the Xenogen IVIS® imaging system to measure how long photons continued to be emitted in the inner ear after TT or systemic injections of luciferin, and then compared the associated drug dynamics. Results: The response to TT and IP injections differed significantly. Photons were detected five minutes after TT injection, peaking at ~20 minutes. By contrast, photons were first detected 30 minutes after i.p. injection. TT and i.p. drug delivery time differed considerably. With TT injections, photons were detected earlier than with IP injections. Photon bioluminescence also disappeared sooner. Delivery time varied with TT injections. Conclusions: We speculate that the drug might enter the Eustachian tube from the middle ear. We conclude that inner-ear drug concentration can be maintained longer if the two injection routes are combined. As the size of luciferin differs from that of therapeutics like dexamethasone, combining drugs with luciferin may advance our understanding of in vivo drug delivery dynamics in the inner ear. © 2012 Kanzaki et al.

Abstract Introduction To date, few studies have focused on spinopelvic sagittal alignment as a predisposing factor for the development of degenerative spondylolisthesis (DS). The objectives of this study were to compare differences in spinopelvic sagittal alignment between patients with or without DS and to elucidate factors related to spinopelvic sagittal alignment. Materials and methods A total of 100 patients with or without DS who underwent surgery for lumbar spinal canal stenosis were assessed in this study. Fifty patients with DS (DS group) and 50 age- and gender-matched patients without DS (non-DS group) were enrolled. Spinopelvic parameters including pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), L4 slope, L5 slope, thoracic kyphosis (TK), lumbar lordosis (LL) and sagittal balance were compared between the two groups. In the DS group, the percentage of vertebral slip (% slip) was also measured. Results Several spinopelvic parameters, PI, SS, L4 slope, L5 slope, TK and LL, in the DS group were significantly greater than those in the non-DS group, and PI had positive correlation with % slip (r = 0.35, p0.05). Degrees of correlations among spinopelvic parameters differed between the two groups. In the DS group, PI was more strongly correlated with SS (r = 0.82, p0.001) than with PT (r = 0.41, p0.01). In the non-DS group, PI was more strongly correlated with PT (r = 0.73, p0.001) than with SS (r = 0.38, p0.01). Conclusions Greater PI may lead to the development and the progression of vertebral slip. Different compensatory mechanisms may contribute to the maintenance of spinopelvic sagittal alignment in DS and non-DS patients. © 2012 Springer-Verlag.

The common marmoset (Callithrix jacchus) is a small New World primate that has been used as a non-human primate model for various biomedical studies. We previously demonstrated that transplantation of neural stem/progenitor cells (NS/PCs) derived from mouse and human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) promote functional locomotor recovery of mouse spinal cord injury models. However, for the clinical application of such a therapeutic approach, we need to evaluate the efficacy and safety of pluripotent stem cell-derived NS/PCs not only by xenotransplantation, but also allotransplantation using non-human primate models to assess immunological rejection and tumorigenicity. In the present study, we established a culture method to efficiently derive NS/PCs as neurospheres from common marmoset ESCs. Marmoset ESC-derived neurospheres could be passaged repeatedly and showed sequential generation of neurons and astrocytes, similar to that of mouse ESC-derived NS/PCs, and gave rise to functional neurons as indicated by calcium imaging. Although marmoset ESC-derived NS/PCs could not differentiate into oligodendrocytes under default culture conditions, these cells could abundantly generate oligodendrocytes by incorporating additional signals that recapitulate in vivo neural development. Moreover, principal component analysis of microarray data demonstrated that marmoset ESC-derived NS/PCs acquired similar gene expression profiles to those of fetal brain-derived NS/PCs by repeated passaging. Therefore, marmoset ESC-derived NS/PCs may be useful not only for accurate evaluation by allotransplantation of NS/PCs into non-human primate models, but are also applicable to analysis of iPSCs established from transgenic disease model marmosets. © 2012 Shimada et al.

BACKGROUND: Despite numerous articles on the use of artificial nerve conduits, autologous nerve transplants remain the most effective for nerve repair. To improve this technique, the authors examined conduits containing gelatin hydrogel as a carrier enabling the sustained release of basic fibroblast growth factor (bFGF). METHODS: To confirm sustained bFGF release in vivo, nerve-guide tubes containing iodine-125-labeled bFGF with or without gelatin hydrogel were implanted under the skin of mice, and the remaining radioactivity was measured. Next, a 15-mm segment of the sciatic nerve was resected and repaired with autologous nerve (group 1), a tube with gelatin hydrogel and bFGF (group 2), a tube with bFGF alone (group 3), or a tube only (group 4). Histologic and functional analyses were performed for 16 weeks after surgery. RESULTS: The radioactivity from iodine-125-labeled bFGF incorporated into gelatin hydrogel decreased more slowly than iodine-125-labeled bFGF alone. Four weeks after surgery, significantly more regenerating axons were detected in group 2 than in groups 3 and 4, but the axonal density in group 2 was lower than in group 1. Similarly, the animals in group 2 showed significantly better motor performance than those in groups 3 and 4, but worse than those in group 1. The animals in groups 1 and 2 showed significantly better sensory recovery than those in groups 3 and 4. CONCLUSIONS: The nerve-guide tube containing gelatin hydrogel and bFGF promoted axonal regeneration after peripheral nerve injury, but not as well as autologous transplants. Understanding the limitations of this technique will facilitate its improvement for clinical applications. Copyright © 2012 by the American Society of Plastic Surgeons.

Synovial sarcoma is an aggressive soft tissue sarcoma with only a modest response to conventional cytotoxic agents. In the present study, we evaluated the potential antitumor effects of a novel anti-angiogenesis agent, pazopanib, against synovial sarcoma cells. We found that pazopanib directly inhibited the growth of synovial sarcoma cells by inducing G1 arrest. Multiplex analyses revealed that the PI3K-AKT pathway was highly suppressed in pazopanib-sensitive synovial sarcoma cells. Furthermore, administration of pazopanib highly suppressed the tumor growth in a xenograft model. Taken together, these results suggest pazopanib as a possible agent against synovial sarcoma and may warrant further clinical studies. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Several biomarkers have been used to evaluate osteoarthritis of the limb joints. Here we evaluated the use of serum cartilage metabolites as biomarkers for degenerative lumbar scoliosis (DLS). Fifty-two DLS patients with Cobb angle>10° were compared with 19 control patients. Serum levels of hyaluronic acid (HA), keratan sulfate (KS), cartilage oligomeric matrix protein (COMP), collagen type II cleavage (C2C), and procollagen type II C-propeptide (CPII) were measured. Serum levels of KS (DLS 1.20±0.44μg/ml vs. control 0.98±0.33μg/ml), CPII (DLS 1905.1±948.2ng/ml vs. control 1223.6±884.4ng/ml), and C2C (DLS 219.1±59.2ng/ml vs. control 177.7±71.7ng/ml) were significantly higher in DLS. There were no significant differences in the levels of HA or COMP. There was a significant positive correlation between the Cobb angle and CPII in DLS. This is the first study to evaluate the cartilage biomarkers in DLS. The results suggest DLS patients have higher levels of type II collagen synthesis and degradation, indicated by elevated serum CPII and C2C, respectively. As type II collagen is a major component of collagens in the nucleus pulposus and facet joint cartilages, its enhanced turnover may be related to the development and progression of DLS. Copyright © 2012 Orthopaedic Research Society.

Object. This study was conducted to determine whether postoperative changes in the fractional anisotropy (FA) value and diffusion tensor imaging of the cervical spinal cord can predict functional outcome for patients with cervical compressive myelopathy (CCM). Methods. Twenty patients with CCM were treated by laminoplasty from 2008 to 2009. Both T2-weighted MRI and diffusion tensor imaging were performed before and after surgery. The FA values were analyzed and fiber tracking was performed. The fiber tract (FT) ratio was calculated according to the following formula: (number of fibers at the compressed level)/(number of fibers at the C-2 level) x 100%. The Japanese Orthopaedic Association scoring system for cervical myelopathy was used to determine pre- and postoperative neurological status of the patients, and the Hirabayashi method was used to calculate the recovery rate. Results. There was no significant difference in recovery rates between patients with and those without intramedullary high signal intensity on preoperative T2-weighted images. Substantial differences in FA value among spinal cord, bone, and CSF made it difficult to obtain a precise FA value for the compressed spinal cord. There was a significant correlation between the preoperative FT ratio and the recovery rate (p = 0.0006). A poor outcome (recovery rate < 40%) could be anticipated for CCM patients with preoperative FT ratios below 60%. Conclusions. The preoperative FT ratio correlated significantly with the recovery rates in CCM patients. Preoperative diffusion tensor tractography can be a new prognostic predictor for neurological recovery in CCM patients after laminoplasty.

BACKGROUND: Because an idiopathic spinal extradural arachnoid cyst (SEAC) is rare, its optimal surgical treatment remains controversial. OBJECTIVE: To evaluate the results of surgical treatments for SEACs and to clarify features of the disease associated with poor outcomes. METHODS: Twelve patients with SEACs who underwent surgery at our hospital between 1988 and 2008 were examined retrospectively. The mean follow-up period was 4.7 years. Total resection of the cyst was performed in 7 patients and closure of the dural defect without cyst resection in 5 patients. Surgical outcomes were evaluated with regard to the duration of symptoms, the size of the cyst, and the surgical procedure used. RESULTS: Neurological recovery was observed in all patients, and there was no recurrence. Poor outcomes were observed in patients with a long duration of symptoms (>1 year, P < .01) and large cyst size (>5 vertebrae, P < .05). The surgical procedure had no significant association with the postoperative neurological recovery. However, there was a significant difference in the degree of the mean postoperative kyphotic angle between the patients treated by total resection of the cyst (9.7 degrees) and those treated by closure of the dural defect without cyst resection through selective laminectomy (2.2 degrees) (P < .01). CONCLUSION: There was no significant difference in postoperative neurological recovery between the 2 surgical procedures. However, closure of the dural defect without cyst resection was less invasive, preventing postoperative kyphotic deformity of the thoracolumbar spine. Copyright © 2012 by the Congress of Neurological Surgeons.

Introduction: Reports of functional recovery from spinal cord injury (SCI) after the transplantation of neural stem cells (NSCs) derived from fetus/embryonic stem cells (ESCs), has raised great expectations for the successful clinical use of stem cell transplantation therapy. However, the ethical issues involved in destroying human embryos or fertilized oocytes to obtain NSCs have been a major obstacle to developing clinically useful stem cell sources, and the transplantation of stem cells isolated from other human embryonic tissues has not yet been developed for use in clinical applications. Areas covered: Recently, induced pluripotent stem cells (iPSCs), which can serve as a source of cells for autologous transplantation, have been attracting a great deal of attention as a clinically viable alternative to stem cells obtained directly from tissues. In this review, the authors outline the neural induction of ESC/iPSC, their therapeutic efficacy in SCI and their safety in vivo. Expert opinion: Although iPSCs offer great promise as the cell source for autologous transplantation for SCI, safety issues including tumorigenicity should be determined prior to the clinical trial. © 2012 Informa UK, Ltd.

Study design Retrospective case series. Objective To examine central neuropathic pain after surgical resection of intramedullary spinal cord tumor (IMSCT). Summary of background data Because of the rarity of IMSCT, there is little information about postoperative neuropathic pain after surgical resection. Methods Eighty-five of 105 patients treated surgically for IMSCT at our hospital between 2000 and 2008 completed the Neuropathic Pain Symptom Inventory (NPSI) and the short form (SF)-36 health inventory. The NPSI score was analyzed against the tumor type and the postoperative Japanese Orthopaedic Association (JOA) score for neurological symptoms. Results The mean NPSI score of the patients was 13.5. The subscore for paresthesia/dysesthesia was significantly higher than the other subscores. Analysis of the NPSI scores by tumor type revealed no significant differences among patients with ependymoma, astrocytoma, and vascular tumors. The postoperative JOA score showed a weak negative correlation with the NPSI score in patients with thoracic spinal cord tumor, and no correlation in those with cervical tumor. In the 11 patients with hemangioblastoma, intense pain was reported at the level of the tumor, although postoperative paralysis was mild. All the postoperative SF-36 subscores of our study patients were significantly lower than the national average, and a significant negative correlation was observed between the SF-36 and the NPSI subscores. Conclusion Neuropathic pain after surgical resection reduces the QOL of patients with IMSCTs, and pain severity varies with the tumor's location and histological features, the severity of paralysis, and the location of pain relative to the tumor. © The Japanese Orthopaedic Association 2012.

Study Design: A prospective follow-up study. Objective: To elucidate the impact of lamina closure on long-term outcomes after open-door laminoplasty. Summary of Background Data: In a previous study, we did not find significant associations between lamina closure and short-term outcomes. Methods: Of the original cohort of 82 patients who underwent open-door laminoplasty, 69 were included in this study (52 men, 17 women; mean age, 60.9 yr; mean follow-up, 6.2 yr; 56 with spondylosis or disc herniation, 13 with ossification of posterior longitudinal ligament). Lamina closure was previously observed in 23 of these patients (closure group) but not in 46 (nonclosure group). The Japanese Orthopaedic Association (JOA) scores and Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire were recorded. Results: The JOA score was 9.9 ± 3.2 in the closure group and 11.2 ± 2.3 in the nonclosure group before surgery (P = 0.1), 13.8 ± 2.3 and 13.8 ± 2.2 at 1.8 years (P = 0.99), and 13.6 ± 2.2 and 14.2 ± 2.7 at final follow-up (P = 0.29). The recovery rate of the JOA scores was 56.7 ± 30.0% and 46.7 ± 29.2% at 1.8 years (P = 0.22) and 51.0 ± 32.5 and 57.6 ± 31.1 at the final follow-up (P = 0.42). The subdomains assessed by the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire at follow-up were cervical spine function, 68.7 ± 27.5 in the closure group and 67.7 ± 30.0 in the nonclosure group (P = 0.93); upper extremity function, 78.6 ± 24.3 and 87.6 ± 15.4 (P = 0.40); lower extremity function, 69.9 ± 26.0 and 73.9 ± 22.5 (P = 0.68); bladder function, 74.6 ± 22.6 and 84.9 ± 29.2 (P = 0.18); and quality of life, 53.9 ± 25.3 and 56.2 ± 18.1 (P = 0.96). Conclusion: Lamina closure did not significantly impact the long-term surgical outcomes of laminoplasty for cervical myelopathy. Although not statistically significant, the recovery rate tended to decline in the closure group compared with the nonclosure group during the long-term follow-up period, and the utilization of a laminar retention device to prevent the laminar closure should be considered. Copyright © 2012 Lippincott Williams & Wilkins.

Neural stem cells (NSCs) were directly induced from mouse fibroblasts using four reprogramming factors (Oct4, Sox2, Klf4, and cMyc) without the clonal isolation of induced pluripotent stem cells (iPSCs). These NSCs gave rise to both neurons and glial cells even at early passages, while early NSCs derived from clonal embryonic stem cells (ESCs)/iPSCs differentiated mainly into neurons. Epidermal growth factor-dependent neurosphere cultivation efficiently propagated these gliogenic NSCs and eliminated residual pluripotent cells that could form teratomas in vivo. We concluded that these directly induced NSCs were derived from partially reprogrammed cells, because dissociated ESCs/iPSCs did not form neurospheres in this culture condition. These NSCs differentiated into both neurons and glial cells in vivo after being transplanted intracranially into mouse striatum. NSCs could also be directly induced from adult human fibroblasts. The direct differentiation of partially reprogrammed cells may be useful for rapidly preparing NSCs with a strongly reduced propensity for tumorigenesis. © AlphaMed Press.

Purpose: The objective of this study was to evaluate 2 years post-surgical loss of three-dimensional correction in adolescent idiopathic scoliosis (AIS) patients using multi-planar reconstruction computed tomography (CT). Methods: Twenty-seven AIS patients treated by segmental pedicle screw (PS) constructs were included in this study. Correction in the axial plane was evaluated using the "relative apical vertebral rotation angle" (rAVR), defined as the difference between the axial rotation angles of the upper instrumented vertebra and the apical vertebra on reconstructed axial CT images. The Cobb angle of the main curve and apical vertebral translation was measured to evaluate the coronal correction. Thoracic kyphosis was also measured for the evaluation of sagittal profile. Measurements were performed before surgery, and 1 week and 2 years after surgery. The relationships between the correction losses and skeletal maturity, and variety of spinal constructs were also evaluated. Results: The mean preoperative Cobb angle of the major curve was 59.1° ± 11.2° before and 13.0° ± 7.2° immediately after surgery. Two years later, the mean Cobb angle had increased significantly, to 15.5° ± 7.8°, with a mean correction loss of 2.5° ± 1.5° (p<0.001). The mean preoperative rAVR of 28.5° ± 8.4° was corrected to 15.8° ± 7.8° after surgery. It had increased significantly to 18.5 ± 8.4 by 2 years after surgery, with a mean correction loss of 2.7° ± 1.0° (p<0.001). The mean correction losses for both the Cobb angle and rAVR were significantly greater in the skeletally immature patients. The significant correlations were recognized between the correction losses and the proportion of multi-axial screws, and the materials of constructs. Conclusions: Statistically significant loss of correction in the Cobb angle and apical vertebral axial rotation angle (AVR) were recognized 2 years after surgery using PS constructs. The correction losses, especially AVR, were more evident in the skeletally immature patients, and in patients treated with more multi-axial screws and with titanium constructs rather than with stainless constructs. © Springer-Verlag 2012.

STUDY DESIGN.: Retrospective case series. OBJECTIVE.: To evaluate the treatment strategies for spinal meningioma. SUMMARY OF BACKGROUND DATA.: Although previous studies have demonstrated favorable surgical outcomes for spinal meningioma, with a low incidence of tumor recurrence, few have examined long-term surgical outcomes. METHODS.: The influence of patient age, surgical margin status (Simpson grade), tumor location, and histological subtype on tumor recurrence were examined retrospectively. In addition, the resected dura mater from Simpson grade I cases was examined for invasive tumor cells and compared with the presence or absence of a dural tail sign on magnetic resonance image. RESULTS.: Complete resection (Simpson grades I and II) was performed in 62 patients. Among them, the tumor recurrence rate was 9.7%, all in patients who underwent grade II resection for ventral spinal lesions. The mean duration to reoperation in these patients was 12.2 ± 5.2 years. Of the 6 patients who underwent incomplete resection (Simpson grade III/IV), all required reoperation for tumor recurrence or regrowth, 5 years later on average. Patients younger than 50 years at the initial surgery had a significantly higher recurrence rate than those aged 50 years or older. Histologic examination of 43 dura mater specimens from Simpson grade I-resection patients revealed tumor cell invasion between the inner and outer layers in 15 patients. This invasion was noted in 8 (29%) of 28 patients who were negative for the dural tail sign on magnetic resonance image, and in 7 (47%) of 15 patients who showed a positive dural tail sign. The MIB-1 index reached about 10% for dumbbell-type meningiomas invading the vertebral body; these were associated with repeated recurrence and unfavorable prognosis. CONCLUSION.: Long-term follow-up after surgery for meningiomas indicated that Simpson grade I resection should be selected whenever practicable when treating younger patients or dumbbell-type meningiomas. Tumors recurred at 12 years, on average, in approximately 30% of patients who underwent grade II resection. Copyright © 2012 Lippincott Williams &Wilkins.

Objective To evaluate the morphologic characteristics of the thoracic pedicle with regard to safe free-hand thoracic pedicle screw placement, based on multi-planar reconstruction CT images. Methods Thirty adolescent idiopathic scoliosis (AIS) patients who had undergone posterior corrective surgery for major thoracic curve were included in this study. Reconstructed CT axial images at each thoracic vertebra were used to measure: (1) the shortest distance from an entry point to the ventral cortex of the lamina (critical distance), and (2) the distance from the entry point to the tangent of the spinal canal at the medial wall of the pedicle (safe distance). The critical length was defined as the distance between the critical distance and the safe distance. The distance from the entry point to the medial wall breach site (breach distance) was measured on post-operative CT images. Results The mean critical distance was 9.3 ± 1.1 mm. The critical distance of vertebrae from different levels was relatively constant, between 8.1 and 10.1 mm. The mean safe distance was 15.2 ± 1.3 mm. The safe distance of vertebrae from different levels was also relatively constant, between 14.5 and 16 mm. The mean critical length was 5.9 ± 1.0 mm. The critical length of vertebrae between T3 and T12 was relatively constant, ranging from 5 to 6.5 mm. The mean breach distance was 12.3 ± 1.3 mm and the each breach always recognized between the critical distance and the safe distance. Conclusions The risk of pedicle medial wall perforation increases as the pedicle probe advances beyond the critical distance of 8-10 mm from the entry point, while it decreases entering into the safe distance at 14.5-16 mm. These parameters were relatively constant even in the most rotated vertebrae at T9 or those with the narrowest pedicle at T7 or T4. © Springer-Verlag 2011.

Study Design.: Prospective clinical series. Objective.: To investigate the sterility of the posterior elements of the spine during posterior correction surgery. Summary of Background Data.: Bacterial growth in the operating field is considered one of the causes of surgical-site infection. Methods.: A total of 80 consecutive patients (mean age = 19.5 years) who underwent posterior correction surgery for spinal deformities were included in the study. During surgery, specimens for bacterial culture were obtained by swabs from (1) the skin after cleansing using povidone-iodine scrub solution but before draping, (2) laminae immediately after exposure, (3) laminae immediately after screw placement, (4) laminae immediately before wound closure, (5) a small piece of bone obtained from the spinous process immediately after exposure and placed on a sterile dish during surgery as a control, kept covered, and (6) a similar sample as (5), kept uncovered. The culture was conducted on both blood agar and Gifu anaerobic medium agar plates. Results.: No patient developed surgical-site infection. The culture was positive in specimen (S) 1 in 25 patients (31.3%), S2 in 20 (25%), S3 in 25 (31.3%), S4 in 26 (32.5%), S5 in 6 (7.5%), and S6 in 7 (8.8%). Bacterial species included Propionibacterium acnes in 15 specimens, Propionibacterium species in 9, and others in 10. Of the 25 patients with a positive culture in S1 and 55 patients without, 22 (88%) and 26 (47.3%), respectively, demonstrated a positive culture in specimens obtained during surgery. Conclusion.: The culture was more frequently positive in specimens obtained immediately before wound closure than in those harvested immediately after exposure and isolated from the surgical field. The results suggest that bacterial contamination of the operating field may originate from the skin of the patient during surgery. © 2012 Lippincott Williams and Wilkins.