Search

This is the first time that the feasibility of space charge measurements on full-sized HVDC cable joints has been explicitly considered. In this article we also consider whether the PEA and TSM techniques could be used. [ABSTRACT FROM AUTHOR]

To improve measurement accuracy of spectrally distorted fiber Bragg grating temperature sensors, reflection profiles were curve fitted to Gaussian shapes, of which center positions were transformed into temperature information. By applying the Gaussian curve-fitting algorithm in a tunable bandpass filter demodulation scheme, ~0.3 [degrees]C temperature resolution was obtained with a severely distorted grating sensor, which was much better than that obtained using the highest peak search algorithm. A binary search was also used to retrieve the optimal fitting curves with the least amount of processing time. OCIS codes: 120.0120, 120.2230, 060.2300.

We use first-principles density functional theory calculations to understand how oxygen vacancies degrade the electrical conductivity of mixed ionic-electronic conductor (MIEC) at low oxygen partial pressure (PO2). Analysis focused on La0.5Sr0.5FeO3−δ, which shows the highest mixed conductivity among cobalt-free iron-based perovskite oxides. Calculation results show that hole compensation by electrons released from oxygen vacancies lowers the electrical conductivity and eventually leads to metal-to-semiconductor transition at low PO2. Analyses of effective mass change and charge-density show that holes are the major charge carrier of electrical conductivity, but the contribution of electrons to conductivity increases as temperature increases. We suggest several possible ways to reduce the degradation of electrical conductivity at low PO2. Our results provide guidelines to design highly effective oxygen-selective membranes. [ABSTRACT FROM AUTHOR]

Objective: Results following anterior cervical discectomy (ACD) without fusion are not well reported because of skepticism that the disturbed cervical spine anatomy after ACD might compromise clinical outcome. The purpose of this study was to determine whether ACD without fusion prompts the degenerative process significantly, and whether it is necessary to preserve disc height and cervical alignment for the sake of better clinical outcome following cervical spine surgery. Background data: Out of 56 consecutive patients, 37 patients who replied and consequently underwent postoperative MRI from April to June 2009 were included in this study. Material and methods: A total of 37 consecutive patients diagnosed as having cervical monoradiculopathy and treated with percutaneous endoscopic cervical discectomy (PECD) were investigated. Angle of cervical lordosis, change in cervical range of motion, disc height change, and degree of degenerative changes at the corresponding level were evaluated. The visual analogue scale (VAS) score for neck and arm pain and the neck disability index (NDI) were compared preoperatively and at the final follow-up. The mean follow-up period was 45.5 months. Results: Despite prompted radiological deterioration such as loss of disc height (the posterior disc heights and central disc height ratio were significantly decreased from 3.6 to 2.6 mm, from 30.3% to 24.5%, respectively, p<0.05) or degenerative progression (from average grade of 2.8 to 4.1, p<0.05), the patients achieved significant improvement in clinical outcomes (VAS for neck and arm dropped from mean 6.3 and 7.5 to 2.7 and 2.6, respectively, and NDI score improved from 46.8% to 17.2%, p<0.05) after PECD. Conclusions: Neither loss of disc height nor progression of degeneration at disc space compromised clinical outcome after PECD without fusion on long-term follow-up. [ABSTRACT FROM AUTHOR]

Objective: Multilevel Oblique Corpectomy (MOC) is an emerging technique for surgical treatment of multi-segmental cervical spondylotic myelopathy (CSM) featuring extensive ossification of the posterior longitudinal ligament (OPLL). However, the use of an oblique drilling plane is unfamiliar to most surgeons and there is no anatomical landmark present on the posterior portion of the vertebral body. To overcome these difficulties, the authors used intraoperative C-arm-based image guided navigation (IGN), and this study was conducted to evaluate the efficacy of IGN in MOC. Methods: Following the introduction of IGN for MOC, 24 patients underwent MOC procedures at our institution. Two patients who had undergone previous cervical operations were excluded from the present study. Of the remaining 22 patients, 11 underwent MOC with IGN, and 11 underwent MOC without IGN support. The completeness of MOC (CMOC) is measured as the sum of the bilateral remaining posterior body minus the remaining approach-side anterior body in millimeters at the most compressive level. For each patient, the preoperative Japanese Orthopaedic Association Score (JOAS) and postoperative 5th day JOAS were collected as well as several other perioperative parameters. Results: The mean CMOC was 0.89 mm for the IGN group and 5.9 mm for the control group. The mean change in JOAS was 5.58 for the IGN group and 3.34 for the control group at 1-year follow-up. In the control group, two patients underwent re-exploration due to remaining OPLL. Despite the intraoperative IGN set-up time, the mean operation time for the IGN group was shorter than that for the control group (248 min versus 259 min). Mean treated levels were 3.55 for the IGN group and 3.36 for the control group. Conclusion: Through the use of image guided navigation, it was possible to accomplish faster and more complete MOC. [ABSTRACT FROM AUTHOR]

This study presents a solution-gated graphene field effect transistor (GFET) for a TP53 DNA sensor using a unique coplanar electrode array integrated with a microfluidic chip. The integrated microfluidic channel controls the exact amount of solution to be delivered. The cancer-related gene, TP53, was applied over the graphene active layers to monitor the sensing performance of the solution-gated GFET. After immobilization of the probe DNA, we hybridized the target DNA with different concentrations (10 μM–1 nM) onto each electrode array. The limit of the detection value obtained herein was 1 nM. To validate the selectivity, when the noncomplementary and one-mismatched DNA molecules were injected into the microchannel, the Dirac point shift values were not significant. The shift of the Dirac point occurs owing to the doping effect caused by the negative charges of the DNA over the graphene surface. When the measurements were reproduced in eight other electrode pairs in the array structure, the transfer curves presented similar Dirac point values, i.e., approximately ±1 mV, indicating the stability of the device. The developed solution-gated GFET sensor provides a reliable measurement of the electrical characteristics and a multiplex detection for cancer diagnostics using a large area of the graphene platform. [ABSTRACT FROM AUTHOR]

Abstract: A high voltage impulse (HVI) technique was applied for the control of membrane bio-fouling caused due to the filtration of microorganisms. Escherichia coli was used as a model microorganism for membrane filtration. The death rate of the cells increased with increasing electric fields (E) strength from 5 to 20kV/cm. In particular, the cell numbers decreased from 3.7×105 to 2.5×103 CFU/ml (99.3% reduction) when subjected to an HVI of 20kV/cm for 60min. The model equation for HVI disinfection; E1.94 ·t=1.3×104, was obtained by plotting the contact time (t) vs. E for 2-log removal (99% reduction) of microorganisms. E. coli Suspensions, both with and without HVI induction, were filtered through an ultrafiltration membrane to verify if the HVI enhanced the filtration performance. The flux of the suspension subjected to HVI was constantly maintained throughout the entire filtration period; whereas, that of the control (without HVI induction) abruptly decreased after the onset of membrane filtration. The main reason for the improved flux was the reduced cake resistance (Rc) as a result of the increased cell particle sizes after HVI induction. E coli cells became coagulated after being subjected to HVI and; thus, the particle size increased. The HVI system could be used as an alternative method for the control of membrane bio-fouling. [Copyright &y& Elsevier]

Si 2 Te 3 is attracting attention due to its compatibility with Si technology while still showing advantages as a two-dimensional layered material. Although recent experimental studies have observed the resistive switching process in Si 2 Te 3 -based memristors, the mechanism has not been clearly identified. In this study, first-principles density functional theory calculations are employed to understand the relationship between the phase transition of Si 2 Te 3 and the reversible resistive switching of the Si 2 Te 3 -based memristor. Our calculation results show that although semiconducting Si 2 Te 3 is energetically more stable than two metallic Si 2 Te 3 phases (α and β), two metallic Si 2 Te 3 can be energetically stabilized by excess holes. The enhanced energetic preference of two metallic Si 2 Te 3 by excess holes is explained by the reduced occupation of antibonding states between Si and Te. Our study finds that the energy barrier for the phase transition between semiconducting Si 2 Te 3 and α-metallic Si 2 Te 3 varies significantly by excess charge carriers so the phase transition can be directly connected to the reversible resistive switching of the Si 2 Te 3 -based memristor under external bias. Our finding will serve as a cornerstone for optimizing the resistive switching process of the Si 2 Te 3 -based memristor.

Applications that provide versatile, high temperature warnings require the development of thermochromic materials based on solid-state oxides. To boost the visible thermochromic properties, a fundamental approach to reveal the unclear roles of local structure on band structure modulation should be considered by scrutinizing the thermal motion of phonon modes. Herein, we demonstrate that selective coupling of intra-layer phonon modes intensifies the visible thermochromism of layered oxides α-MoO 3 . As a result of thermally induced band gap reduction in α-MoO 3 , the observed color reversibly changes from white at 25 °C to yellow at 300 °C owing to a red shift of the absorption edge with an increase of temperature. This high-temperature thermochromism is attributed to the anisotropic change of layered α-MoO 3 crystal structures characterized by synchrotron X-ray diffraction. Notably, quantitative characterizations combined with theoretical calculations reveal that the cooperative coupling of active Raman modes in intra-layer [MoO 6 ] octahedra are responsible for the band gap reduction at high temperature; this defies the general belief regarding the origin of visible thermochromism in layered oxides as the modulation of a van der Waals inter-layer distance. These original results can aid the development of a new strategy to further intensify high-temperature thermochromism by anion doping for highly sensitive temperature-indicating applications.

The ability to realize a highly capacitive/conductive electrode is an essential factor in large-scale devices, requiring a high-power/energy density system. Germanium is a feasible candidate as an anode material of lithium-ion batteries to meet the demands. However, the application is constrained due to low charge conductivity and large volume change on cycles. Here, we design a hybrid conductive shell of multi-component titanium oxide on a germanium microstructure. The shell enables facile hybrid ionic/electronic conductivity for swift charge mobility in the germanium anode, revealed through computational calculation and consecutive measurement of electrochemical impedance spectroscopy. Furthermore, a well-constructed electrode features a high initial Coulombic efficiency (90.6%) and stable cycle life for 800 cycles (capacity retention of 90.4%) for a fast-charging system. The stress-resilient properties of dense microparticle facilitate to alleviate structural failure toward high volumetric (up to 1737 W h L -1 ) and power density (767 W h L -1 at 7280 W L -1 ) of full cells, paired with highly loaded NCM811 in practical application.

Tin-halide perovskite solar cells (Sn-PSCs) are promising candidates as an alternative to toxic lead-halide PSCs. However, Sn 2+ is easily oxidized to Sn 4+ , so Sn-PSCs are unstable in air. Here, we use first-principles density functional theory calculations to elucidate the oxidation process of Sn 2+ at the surface of ASnBr 3 [A = Cs or CH 3 NH 3 (MA)]. Regardless of the A-site cation, adsorption of O 2 leads to the formation of SnO 2 , which creates a Sn vacancy at the surface. The A-site cation determines whether the created vacancies are stabilized in the bulk or at the surface. For CsSnBr 3 , the Sn vacancy is stabilized at the surface, so further oxidation is limited. For MASnBr 3 , the Sn vacancy moves into bulk region, so additional Sn is supplied to the surface; as a result, a continuous oxidation process can occur. The stabilization of Sn vacancy is closely related to the polarization that the A-site cation causes in the system.

As a representative photocatalyst for photoelectrochemical solar water splitting, TiO 2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO 2 , rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H + . which has the minimum formation energy among three states of hydrogen (H + . H 0 , and H - ). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO 2 .

Study Design: A biomechanical comparison among the intact C2 to C7 segments, the C5 to C6 segments implanted with fusion cage, and three different artificial disc replacements (ADRs) by finite element (FE) model creation reflecting the entire cervical spine below C2., Objective: The aim of this study was to analyze the biomechanical changes in subaxial cervical spine after ADR and to verify the efficacy of a new mobile core artificial disc Baguera C that is designed to absorb shock., Summary of Background Data: Scarce references could be found and compared regarding the cervical ADR devices' biomechanical differences that are consequently related to their different clinical results., Methods: One fusion device (CJ cage system, WINNOVA) and three different cervical artificial discs (Prodisc-C Nova (DePuy Synthes), Discocerv (Scient'x/Alphatec), Baguera C (Spineart)) were inserted at C5-6 disc space inside the FE model and analyzed. Hybrid loading conditions, under bending moments of 1 Nm along flexion, extension, lateral bending, and axial rotation with a compressive force of 50 N along the follower loading direction, were used in this study. Biomechanical behaviors such as segmental mobility, facet joint forces, and possible wear debris phenomenon inside the core were investigated., Results: The segmental motions as well as facet joint forces were exaggerated after ADR regardless of type of the devices. The Baguera C mimicked the intact cervical spine regarding the location of the center of rotation only during the flexion moment. It also showed a relatively wider distribution of the contact area and significantly lower contact pressure distribution on the core than the other two devices. A "lift off" phenomenon was noted for other two devices according to the specific loading condition., Conclusion: The mobile core artificial disc Baguera C can be considered biomechanically superior to other devices by demonstrating no "lift off" phenomenon, and significantly lower contact pressure distribution on core., Level of Evidence: N/A.

In spite of the key role of hydrogen bonding in the structural stabilization of the prototypic hybrid halide perovskite, CH3NH3PbI3 (MAPbI3), little progress has been made in our in-depth understanding of the hydrogen-bonding interaction between the MA(+)-ion and the iodide ions in the PbI6-octahedron network. Herein, we show that there exist two distinct types of the hydrogen-bonding interaction, naming α- and β-modes, in the tetragonal MAPbI3 on the basis of symmetry argument and density-functional theory calculations. The computed Kohn-Sham (K-S) energy difference between these two interaction modes is 45.14 meV per MA-site with the α-interaction mode being responsible for the stable hydrogen-bonding network. The computed bandgap (Eg) is also affected by the hydrogen-bonding mode, with Eg of the α-interaction mode (1.73 eV) being significantly narrower than that of the β-interaction mode (2.03 eV). We have further estimated the individual bonding strength for the ten relevant hydrogen bonds having a bond critical point.

Background: Percutaneous endoscopic lumbar discectomy (PELD) has remarkably evolved with successful results. Although PELD has gained popularity for the treatment of herniated disc (HD), the risk of surgical failure may be a major obstacle to performing PELD. We analyzed unsuccessful cases requiring reoperation., Objective: To find common causes of surgical failure and elucidate the limitations of the conventional PELD technique., Methods: A retrospective review was performed on all patients who had undergone PELD between January 2001 and December 2012. Unsuccessful PELD was defined as a case requiring reoperation within 6 weeks after primary surgery. Chart review was done, and preoperative, intraoperative, and postoperative radiographic reviews were performed. All unsuccessful PELD cases were classified according to the type of HD, location of herniation, extruded disc migration, working channel position, and intraoperative and postoperative findings., Results: In 12 years, 10,228 patients had undergone PELD; 436 (4.3%) cases were unsuccessful. The causes were incomplete removal of HDs in 283 patients (2.8%), recurrence in 78 (0.8%), persistent pain even after complete HD removal in 41 (0.4%), and approach-related pain in 21 (0.2%). Incomplete removal of the HD was caused by inappropriate positioning (95 cases; 33.6%) of the working channel and occurred in central HDs (91 cases; 32.2%), migrated HDs (70 cases; 24.7%), and axillary type HDs (63 cases; 22.3%)., Conclusion: Proper surgical indications and good working channel position are important for successful PELD. PELD techniques should be specifically designed to remove the disc fragments in various types of HD.

Study Design: Retrospective clinical study., Objective: To evaluate the effect of the limitation of flexion rotation clinically and radiologically after interspinous soft stabilization using a tension band system in grade 1 degenerative spondylolisthesis., Summary of Background Data: Although several studies have been published on the clinical effects of limiting rotatory motion using tension band systems, which mainly targets the limitation of flexion rather than that of extension, they were confined to the category of pedicle screw-based systems, revealing inconsistent long-term outcomes., Methods: Sixty-one patients with a mean age of 60.6 years (range, 28-76 yr) who underwent interspinous soft stabilization after decompression for grade 1 degenerative spondylolisthesis with stenosis between 2002 and 2004 were analyzed. At follow-up, the patients were divided into 2 groups on the basis of their achievement or failure to achieve flexion limitation. The clinical and radiological findings were analyzed. A multiple linear regression analysis was performed to determine the prognostic factors for surgical outcomes., Results: At a mean follow-up duration of 72.5 months (range, 61-82 mo), 51 patients were classified into the flexion-limited group and 10 into the flexion-unlimited group. Statistically significant improvements were noted only in the flexion-limited group in all clinical scores. In the flexion-unlimited group, there were significant deteriorations in flexion angle (P = 0.009), axial thickness of the ligamentum flavum (P = 0.013), and the foraminal cross-sectional area (P = 0.011), resulting in significant intergroup differences. The preoperative extension angle was identified as the most influential variable for the flexion limitation and the clinical outcomes., Conclusion: The effects of the limitation of flexion rotation achieved through interspinous soft stabilization using a tension band system after decompression were related to the prevention of late recurrent stenosis and resultant radicular pain caused by flexion instability. The extension potential at the index level was recognized as a major prognostic factor that can predict the flexion limitation and the clinical results., Level of Evidence: 4.

The stability of screw constructs is of considerable importance in determining the outcome, especially in spinal osteoporosis. Polymethylmethacrylate (PMMA) has been proven as an effective material for increasing the pullout strength of pedicle screws inserted into the osteoporotic bones. However, PMMA has several disadvantages, such as its exothermic properties, the risk of neural injury in the event of extravasation, and difficulties in performing revision surgery. In the current study, we used hydroxyapatite (HA) cement for screw augmentation in spinal osteoporosis. We conclude that HA cement is a useful tool for screw augmentation and recommend it as a promising option for spinal instrumentation in osteoporotic patients.

Study Design: Retrospective clinical study., Objective: The purpose of this study was to examine the changes in spinopelvic alignment after interspinous soft stabilization (ISS) with a tension band system and to identify the lumbosacral parameters related to those changes and to determine their impact on the clinical outcomes compared with posterior lumbar interbody fusion (PLIF) in patients with low-grade degenerative spondylolisthesis (DS)., Summary of Background Data: The sacropelvic morphometric changes after fusion surgery have received much research attention. However, few reports have addressed the issue after use of dynamic or soft stabilization systems., Methods: From April 2001 to November 2003, 45 patients presenting with grade 1 DS with stenosis underwent either ISS with a tension band system (ISS group) or PLIF with pedicle screw fixation (PLIF group). The mean follow-up period was 76.8 months. Three pelvic parameters, the sacral slope (SS), pelvic tilt (PT), and pelvic incidence, were investigated to address the sacropelvic morphometric change. Clinical outcomes were assessed using the visual analog scale score, the Oswestry Disability Index, and the patient's satisfaction index., Results: Both groups showed significant improvements in all of the clinical outcomes, with no significant differences between groups. In the ISS group, the SS increased and PT decreased, whereas in the PLIF group, the SS decreased and PT increased, resulting in pelvic anteversion and retroversion, respectively, with significant intergroup differences in SS and PT (SS: P = 0.047; PT: P = 0.01). The positive association of lumbar lordosis with SS (r = 0.448) and its negative association with PT (r = -0.674) in the respective groups indicate the influence of changes in lumbar lordosis on pelvic positional changes. Significant correlations between follow-up segmental lumbar lordosis and the visual analog scale score for leg pain (r = -0.685) and Oswestry Disability Index score (r = -0.425) were found in the ISS group alone., Conclusion: Segmental lordotic change after ISS with a tension band system was the possible decisive factor in the development of pelvic anteversion while maintaining sagittal lumbar balance; lack of lumbar lordosis led to compensatory pelvic retroversion in the PLIF group. Considering the comparable clinical results with PLIF surgery and the achievement of physiologic sagittal spinopelvic balance, the ISS procedure can be a feasible alternative to fusion surgery in patients with grade 1 DS with stenosis.

Object: The purpose of this study was to demonstrate the clinical characteristics of postoperative retroperitoneal hematoma (RPH) following transforaminal percutaneous endoscopic lumbar discectomy (PELD) and to discuss how to prevent the complication of unintended hemorrhage., Methods: The medical records of 412 consecutive patients treated with transforaminal PELD between January 2005 and May 2007 were reviewed. A total of 4 patients (0.97%) experienced symptomatic postoperative RPH. The clinical outcomes were evaluated using the visual analog scale and the Oswestry Disability Index., Results: The common symptom in all patients with a hematoma was inguinal pain. The mean hematoma volume was 527.9 ml (range 53.3-1274.1 ml). Two patients with massive diffuse-type RPHs compressing the intraabdominal structures required open hematoma evacuation performed by general surgeons, and the other 2 patients with small, localized RPHs of < 100 ml were treated conservatively. The mean follow-up period was 21.3 months (range 13-29 months). The mean visual analog scale score for radicular leg pain improved from 7.6 to 1.8 and that for back pain improved from 4.3 to 2. The mean Oswestry Disability Index improved from 58.8 to 9.1%. The preoperative symptoms improved after the second treatment without significant neurological sequelae in all patients., Conclusions: Although transforaminal PELD is a minimally invasive and safe procedure, the possibility of RPH should be kept in mind. Adequate technical and anatomical considerations are important to avoid this unusual hemorrhagic complication, especially in the patient with underlying medical problems or previous operative scarring. A high index of suspicion and early detection is also important to avoid the progression of the hematoma.

Object: The purpose of this study was to evaluate the predictive factors for subsequent vertebral fracture occurring after percutaneous vertebroplasty (PVP) at the neighboring levels (adjacent vs nonadjacent levels)., Methods: The medical records of 508 consecutive patients treated with PVP between January 2000 and December 2002 were retrospectively reviewed. A total of 45 patients with 49 painful vertebral fractures occurring after PVP was identified based on clinical and radiological findings. New vertebral fractures, developing at any of the 3 consecutive vertebral bodies (VBs) above or below the previously treated level, were the focus of the study. The patients were divided into 3 groups: an adjacent-level fracture group, nonadjacent-level fracture group, and a control group composed of 50 randomly selected patients in whom there was no evidence of a new fracture. Clinical, imaging, and procedure-related factors for each group were statistically analyzed., Results: In 31 patients 35 VBs were classified as adjacent-level fractures, and in 14 patients 14 VBs were classified as nonadjacent-level fractures. After further vertebroplasty, the overall pain intensity and satisfaction rate in patients with post-PVP fractures were similar to those in the control group. In cases involving adjacent fractures, lower body mass index and intradiscal cement leakage were the significant predictive factors of fracture. In contrast, lower mobility of the index segment was related to nonadjacent-level fracture., Conclusions: According to the authors' results, the mechanisms of subsequent fracture at adjacent and nonadjacent vertebrae are different. A direct pillar effect (that is, the difference in strength caused by cement augmentation) may provoke an adjacent-level fracture, whereas a dynamic hammer effect (the difference in segmental mobility) may lead to a nonadjacent fracture.

Objective: This study reports on the comparative results of a series of patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) who were treated with laser-assisted anterior corpectomy or laminoplasty., Methods: Forty-eight patients (21 patients with anterior corpectomy and 27 patients with laminoplasty) with cervical OPLL involvement of three or more vertebral bodies were retrospectively reviewed. Both pre- and postoperatively neurological status was graded according to the Nurick grading system. The anteroposterior (AP) diameter change at the narrowest part of the spinal canal, the change in the regional and the overall cervical Cobb's angle, and the change in cervical range of motion (ROM) were all measured. The mean follow-up periods were 21.8 mo and 29.1 mo for the corpectomy and laminoplasty patients, respectively., Results: The mean changes in the pre- to postoperative Nurick grades were 1.9 for the corpectomy group and 1 for the laminoplasty group (p < 0.05). The mean changes in the pre- to postoperative spinal canal AP diameters were 9.1 mm and 4.11 mm, respectively, for the corpectomy group and the laminoplasty group (p < 0.05). The mean changes of the regional Cobb's angle were 1.7 degrees and -3.1 degrees (p = 0.06), and the mean changes of the overall cervical Cobb's angle were 1.1 degrees and -1.6 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05). The changes in the cervical degree of ROM were -19.6 degrees and -19.7 degrees , respectively, for the corpectomy group and the laminoplasty group (p > 0.05)., Conclusions: Direct decompression of the spinal cord by laser-assisted anterior cervical corpectomy was shown to be a better surgical option on long-term follow-up, yielding more recovery of neurological deficits, achieving adequate decompression of the spinal canal, and preventing the development of regional kyphosis at the operated level of the spine, in patients with multilevel cervical OPLL.

Object: Recently, diffusion tensor (DT) imaging was introduced to demonstrate white matter tracts. However, research interest has focused on the anatomical rather than the functional aspects of this imaging modality. The authors undertook a functional analysis of DT imaging to determine the relationship between weakness and changes on DT images., Methods: Diffusion tensor images were obtained in 23 patients with lesions located adjacent to the pyramidal tract. Patients were classified according to their motor deficit. Axial magnetic resonance image sections through the maximum tumor diameters were selected and the mean apparent diffusion coefficients (ADCs) and mean fractional anisotropies (FAs) were measured. One ovoid region of interest (ovROI) was placed in the center of the pyramidal tract and another was designed to include the whole pyramidal tract at the same axial level (wROI). To determine intraobserver variability, a single neurosurgeon measured mean ADCs and FAs four times by using these two different ROI types without knowledge of any clinical information. To determine interobserver variability, a second neurosurgeon who was also unaware of any clinical information measured the mean ADCs and FAs by using the wROI method. The five measurements produced the same results. The mean FA at the lesion side of the pyramidal tract was significantly lower in patients with weakness (p < 0.01). Little intraobserver measurement variability occurred using the ovROI method, and no interobserver variability occurred using the wROI method., Conclusions: Motor weakness was significantly related to a low mean FA in the pyramidal tract on the lesion side. Designing an ROI that includes the whole pyramidal tract is an easier and more reproducible method than using an ovROI method.