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To study if spinal motor evoked potentials (SpMEPs), muscle responses after electrical stimulation of the spinal cord, can monitor the corticospinal tract. Study 1 comprised 10 consecutive cervical or thoracic myelopathic patients. We recorded three types of muscle responses intraoperatively: (1) transcranial motor evoked potentials (TcMEPs), (2) SpMEPs and (3) SpMEPs + TcMEPs from the abductor hallucis (AH) using train stimulation. Study 2 dealt with 5 patients, who underwent paired train stimulation to the spinal cord with intertrain interval of 50-60 ms for recording AH SpMEPs. We will also describe two illustrative cases to demonstrate the clinical value of AH SpMEPs for monitoring the motor pathway. In Study 1, SpMEPs and SpMEPs + TcMEPs recorded from AH measured nearly the same, suggesting the collision of the cranially evoked volleys with the antidromic signals induced by spinal cord stimulation via the corticospinal tracts. In Study 2, the first and second train stimuli elicited almost identical SpMEPs, indicating a quick return of transmission after 50-60 ms considered characteristic of the corticospinal tract rather than the dorsal column, which would have recovered much more slowly. Of the two patients presented, one had no post-operative neurological deteriorations as anticipated by stable SpMEPs, despite otherwise insufficient IONM, and the other developed post-operative motor deficits as predicted by simultaneous reduction of TcMEPs and SpMEPs in the face of normal SEPs. Electrical stimulation of the spinal cord primarily activates the corticospinal tract to mediate SpMEPs.

Introduction Facet effusion represents a magnetic resonance imaging finding suggesting accumulation of fluid in the facet joint, potentially predictive of lumbar spondylolisthesis and low back pain. However, its prevalence and epidemiological characteristics in the general population remain unclear, because previous studies only included patients or volunteers. The aim of the present study was to investigate the prevalence of facet effusion in the general population and to describe its potential relationship with spondylolisthesis and low back pain. Material and methods Our study enrolled 808 participants from the Wakayama Spine Study who underwent magnetic resonance imaging investigations in supine position. Facet effusion was defined as a measurable, curvilinear, high-intensity signal within the facet joint, closely matching that of cerebrospinal fluid on the axial T2 images. We used standing lateral radiographs to diagnose L4 spondylolisthesis. Results We found that the prevalence of facet effusion in the lumbar spine was 34.3%, which did not differ significantly between men and women (p=0.13) and did not tend to increase with age, either in men (p=0.81) or in women (p=0.65). Additionally, we found no significant association between facet effusion and low back pain (odds ratio, 1.04-1.49; 95% confidence interval, 0.57-2.64; p=0.17-0.85), or between facet effusion and L4 spondylolisthesis (odds ratio, 1.55; 95% confidence interval, 0.80-2.86; p=0.17). In a subset of participants with L4 spondylolisthesis, we also noted that facet effusion was not significantly associated with low back pain (odds ratio, 1.26; 95% confidence interval, 0.37-4.27; p=0.70). Discussion This is the first study of facet effusion employing a population-based cohort, and the findings are thus expected to accurately describe the relationship between facet effusion and low back pain in the general population. We are planning a follow-up survey of the Wakayama Spine Study cohort to clarify the natural history of facet effusion and its relationship with clinical symptoms.

There is ongoing controversy regarding the most appropriate surgical treatment for lumbar spinal stenosis (LSS) with concurrent degenerative lumbar scoliosis (DLS): decompression alone, decompression with limited spinal fusion, or long spinal fusion for deformity correction. The coexistence of degenerative stenosis and deformity is a common scenario; Nonetheless, selecting the appropriate surgical intervention requires thorough understanding of the patients clinical symptomatology as well as radiographic parameters. Minimally invasive (MIS) decompression surgery was performed for LSS patients with DLS. The aims of this study were (1) to investigate the clinical outcomes of MIS decompression surgery in LSS patients with DLS, and (2) to identify the predictive factors for both radiographic and clinical outcomes after MIS surgery. 438 consecutive patients were enrolled in this study. Inclusion criteria was evidence of LSS and DLS with coronal curvature measuring greater than 10°. The Japanese Orthopaedic Association (JOA) score, JOA recovery rate, low back pain (LBP), and radiographic features were evaluated preoperatively and at over 2 years postoperatively. Of the 438 patients, 122 were included in final analysis, with a mean follow-up of 2.4 years. The JOA recovery rate was 47.6%. LBP was significantly improved at final follow-up. Cobb angle was maintained for 2 years postoperatively (p = 0.159). Clinical outcomes in foraminal stenosis patients were significantly related to sex, preoperative high Cobb angle and progression of scoliosis (p = 0.008). In the severe scoliosis patients, the JOA recovery was 44%, and was significantly depended on progression of scoliosis (Cobb angle: preoperation 29.6°, 2-years follow-up 36.9°) and mismatch between the pelvic incidence (PI) and the lumbar lordosis (LL) (preoperative PI–LL 35.5 ± 21.2°) (p = 0.028). This study investigated clinical outcomes of MIS decompression surgery in LSS patients with DLS. The predictive risk factors of clinical outcomes were severe scoliosis, foramina stenosis, progressive scoliosis and large mismatch of PI–LL.

Introduction Facet effusion represents a magnetic resonance imaging finding suggesting accumulation of fluid in the facet joint, potentially predictive of lumbar spondylolisthesis and low back pain. However, its prevalence and epidemiological characteristics in the general population remain unclear, because previous studies only included patients or volunteers. The aim of the present study was to investigate the prevalence of facet effusion in the general population and to describe its potential relationship with spondylolisthesis and low back pain. Material and methods Our study enrolled 808 participants from the Wakayama Spine Study who underwent magnetic resonance imaging investigations in supine position. Facet effusion was defined as a measurable, curvilinear, high-intensity signal within the facet joint, closely matching that of cerebrospinal fluid on the axial T2 images. We used standing lateral radiographs to diagnose L4 spondylolisthesis. Results We found that the prevalence of facet effusion in the lumbar spine was 34.3%, which did not differ significantly between men and women (p=0.13) and did not tend to increase with age, either in men (p=0.81) or in women (p=0.65). Additionally, we found no significant association between facet effusion and low back pain (odds ratio, 1.04–1.49; 95% confidence interval, 0.57–2.64; p=0.17–0.85), or between facet effusion and L4 spondylolisthesis (odds ratio, 1.55; 95% confidence interval, 0.80–2.86; p=0.17). In a subset of participants with L4 spondylolisthesis, we also noted that facet effusion was not significantly associated with low back pain (odds ratio, 1.26; 95% confidence interval, 0.37–4.27; p=0.70). Discussion This is the first study of facet effusion employing a population-based cohort, and the findings are thus expected to accurately describe the relationship between facet effusion and low back pain in the general population. We are planning a follow-up survey of the Wakayama Spine Study cohort to clarify the natural history of facet effusion and its relationship with clinical symptoms.

Recently, low-frequency multi-train stimulation (MTS) was shown to effectively enhance transcranial motor-evoked potentials (TcMEPs). In contrast, high- frequency double-train stimulation was reported to elicit a marked facilitation. The aim of this study was to evaluate the efficacy of high-frequency MTS in the augmentation of potentials. In addition, we investigated the safety of high-frequency MTS, behaviorally and histologically. TcMEPs were recorded from the triceps surae muscle in 38 rats. A multipulse stimulus was delivered repeatedly at different rates (2, 5, 10, 20, and 50 Hz), and was defined as MTS. A conditioned taste aversion method was used to investigate the effect of high-frequency MTS on learning and memory function. Subsequently, animals were sacrificed, and the brains were removed and examined using the standard hematoxylin-eosin method. Compared with conventional single train stimulation, TcMEP amplitudes increased 1.3, 2.1, 1.9, and 2.0 times on average with 5, 10, 20, and 50 Hz stimulation, respectively. The aversion index was >0.8 in all animals after they received 100 high-frequency MTSs. Histologically, no pathological changes were evident in the rat brains. High-frequency MTS shows potential to effectively enhance TcMEP responses, and to be used safely in transcranial brain stimulation.

Objective This study aimed to establish sex- and age-dependent distributions of the cross sectional area and fatty infiltration ratio of paraspinal muscles, and to examine the correlation between paraspinal muscle degeneration and low back pain in the Japanese population. Methods In this cross-sectional study, data from 796 participants (241 men, 555 women; mean age, 63.5 years) were analyzed. The measurement of the cross sectional area and fatty infiltration ratio of the erector spinae and multifidus from the level of T12/L1 to L4/5 and psoas major at the level of T12/L1 was performed using axial T2-weighted magnetic resonance imaging. Multivariate logistic regression analysis was used to estimate the association between fatty infiltration of the paraspinal muscles and the prevalence of low back pain. Results The cross sectional area was larger in men than women, and tended to decrease with age, with the exception of the erector spinae at T12/L1 and L1/2 in women. The fatty infiltration ratio was lower in men than women, except for multifidus at T12/L1 in 70–79 year-olds and psoas major in those less than 50 years-old, and tended to increase with age. Logistic regression analysis adjusted for age, sex, and body mass index showed that the fatty infiltration ratio of the erector spinae at L1/2 and L2/3 was significantly associated with low back pain (L1/2 level: odds ratio, 1.05; 95% confidence interval, 1.005–1.104; L2/3 level: odds ratio, 1.05; 95% confidence interval, 1.001–1.113). Conclusion This study measured the cross sectional area and fatty infiltration ratio of paraspinal muscles in the Japanese population using magnetic resonance imaging, and demonstrated that the fatty infiltration ratio of the erector spinae in the upper lumbar spine was significantly associated with the presence of low back pain. The measurements could be used as reference values, which are important for future comparative studies.

OBJECTIVE:The purpose of this study was to evaluate the relations between the degree of encroachment, measured as the cross-sectional area of the dural sac, and low back pain in a large population. METHODS:In this cross-sectional study, data from 802 participants (247 men, 555 women; mean age, 63.5 years) were analyzed. The measurement of the cross-sectional area of the dural sac from the level of L1/2 to L4/5 was taken using axial T2-weighted images. The minimum cross-sectional area was defined as the cross-sectional area of the dural sac at the most constricted level in the examined spine. Participants were divided into three groups according to minimum cross-sectional area measurement quartiles (less than the first quartile, between the first and third quartiles, and greater than the third quartile). A multivariate logistic regression analysis was used to estimate the association between the minimum cross-sectional area and the prevalence of low back pain. RESULTS:The mean minimum cross-sectional area was 117.3 mm2 (men: 114.4 mm2; women: 118.6 mm2). A logistic regression analysis adjusted for age, sex, body mass index, and other confounding factors, including disc degeneration, showed that a narrow minimum cross-sectional area (smaller than the first quartile) was significantly associated with low back pain (odds ratio, 1.78; 95% confidence interval, 1.13-2.80 compared to the wide minimum cross-sectional area group: minimum cross-sectional area greater than the third quartile measured). CONCLUSION:This study showed that a narrow dural sac cross-sectional area was significantly associated with the presence of low back pain after adjustment for age, sex, and body mass index. Further investigations that include additional radiographic findings and psychological factors will continue to elucidate the causes of low back pain.

In this paper, we design a mobile augmented reality (AR) system called TweetGlue, which overlays text messages (i.e., tweets) that are posted to a local social networking service onto live view images from cameras in mobile/wearable devices. By displaying the tweets at the current positions of the users who posted them, it supports social interaction between the users. Accurate pose tracking of mobile devices is an essential building block of such mobile AR applications. While visual features that are extracted from scenes are commonly used for vision-based pose estimation, it would not be suitable for such a mobile social AR application because the features may be often occluded by human bodies nearby. To cope with the problem, we leverage an external pedestrian tracking system using a small number of laser-based distance measurement sensors (i.e., LRS sensors) to utilize the surrounding human bodies as virtual markers for pose estimation. The mobile devices periodically analyze images from the embedded camera sensor to estimate relative positions of pedestrians in the images. By matching the estimated relative positions with accurate human location measurements by the LRS sensors, the system robustly identifies location and horizontal orientation of the devices. Through simulation experiments, we show that the TweetGlue system can accurately identify pose of mobile devices in 83% of the simulated scenarios.

The low-temperature specific heat (1.5 K to 6 K), the electrical resistivity (1 K to room temperature) and the magnetoresistance at 1.4, 4.2 and 10 K have been measured for the single-grained I-phase of Al–Li–Cu with near 6:4:1 composition grown by the Bridgman method. An etching method, which allows us to dissolve only the fcc Al second phase completely, was developed. The density of states at the Fermi energy obtained from the electronic specific heat coefficient is extremely small compared with the corresponding free-electron value. The resistivity at 4.2 K is as high as 870 µΩcm and decreases as \({-}{\sqrt{T}}\) below 20 K and as - T above 20 K, indicating the development of the weak localization of electrons. Magnetic field dependence of the magnetoresistance is consistent with the theory of the localization without involving electron-electron interaction.