Long-term efficacy of microendoscopic laminotomy for lumbar spinal stenosis in advanced degenerative spondylolisthesis with or without dynamic spinal instability: a propensity score-matching analysis.

OBJECTIVE: In this study, the authors aimed to determine the mid- to long-term outcomes of microendoscopic laminotomy (MEL) for lumbar spinal stenosis (LSS) with degenerative spondylolisthesis (DS) and identify preoperative predictors of poor mid- to long-term outcomes. METHODS: The authors retrospectively reviewed the medical records of 274 patients who underwent spinal MEL for symptomatic LSS. The minimum postoperative follow-up duration was 5 years. Patients were classified into two groups according to DS: those with DS (the DS+ group) and those without DS (the DS- group). The patients were subjected to propensity score matching based on sex, age, BMI, surgical segments, and preoperative leg pain visual analog scale scores. Clinical outcomes were evaluated 1 year and > 5 years after surgery. RESULTS: Surgical outcomes of MEL for LSS were not significantly different between the DS+ and DS- groups at the final follow-up (mean 7.8 years) in terms of Oswestry Disability Index (p = 0.498), satisfaction (p = 0.913), and reoperation rate (p = 0.154). In the multivariate analysis, female sex (standard ß -0.260), patients with slip angle > 5° in the forward bending position (standard ß -0.313), and those with dynamic progression of Meyerding grade (standard ß -0.325) were at a high risk of poor long-term outcomes. CONCLUSIONS: MEL may have good long-term results in patients with DS without dynamic instability. Women with dynamic instability may require additional fusion surgery in approximately 25% of cases for a period of ≥ 5 years.

Benefits of surgical treatment within 48†h of proximal femoral fracture in centenarians: a retrospective cohort study.

Introduction: Proximal femoral fractures in aging populations represent a significant concern, with an increasing prevalence among individuals aged ≥100 years. The existing research does not provide robust guidance for clinicians managing older patients aged ≥100 years with proximal femoral fractures. We investigated the safety and efficacy of surgical treatment in patients aged ≥100 years with proximal femoral fractures and evaluated the impact of early surgery on their outcomes. Methods: This retrospective cohort study involved 15 patients aged ≥100 years who underwent surgical treatment of proximal femoral fractures; the control group included 137 patients in their 90s. Data were collected between January 2010 and December 2017. Evaluation items included patient characteristics, surgical details, perioperative complication rates, length of hospital stay, the proportion of patients discharged to the same facility or home, rate of regaining walking ability, and 1-year survival rate. Results: The patients aged ≥100 years and those in their 90s had comparable outcomes. Thus, age alone does not dictate surgical success. Early surgery (≤48 h) was associated with trends toward improved perioperative complications, ambulatory ability, and return to original living environment. Discussion: This study underscores the potential benefits of surgical intervention for proximal femoral fractures in patients aged ≥100 years, indicating the relevance of early surgery (≤48 h). Our findings emphasized the importance of timely intervention and evidence-based decision-making for this demographic. Clinicians, policymakers, and patients could benefit from our insights to enhance fracture management strategies, along with future research endeavors to validate and expand our results in larger multicenter cohorts.

Outcomes and Vertebral Osteophytes and Bulging Intervertebral Discs Occupancy as a Decision-Making Tool for Surgical Success in Patients Undergoing Microendoscopic Foraminotomy for Lumbar Foraminal Stenosis.

OBJECTIVE: The objective of this study was to determine the long-term outcomes of microendoscopic foraminotomy in treating lumbar foraminal stenosis and identify the optimal extent of decompression that yields improved results and fewer complications. METHODS: A retrospective cohort study reviewed the medical records of 95 consecutive patients who underwent microendoscopic foraminotomy for lumbar foraminal stenosis. Clinical outcomes were assessed using the Japanese Orthopaedic Association scoring system and visual analog scale for low back and leg pain. Surgical success was determined by meeting significant improvement thresholds for back and leg pain at 2 years postoperatively. Multiple regression analysis identified factors associated with improved pain scores. Receiver operating characteristic curve analysis determined the cut-off values for successful surgeries. RESULTS: Significant improvements were observed in Japanese Orthopaedic Association and visual analog scale scores for back and leg pain 2 years postoperatively compared with preoperative scores (P < 0.0001) and sustained over a ≥5-year follow-up period. Reoperation rates were low and did not significantly increase over time. Multiple regression analysis identified occupancy of the vertebral osteophytes and bulging intervertebral discs (O/D complex) as surgical success predictors. A 45.0% O/D complex occupancy cutoff value was determined, displaying high sensitivity and specificity for predicting surgical success. CONCLUSIONS: This study provides evidence supporting the long-term efficacy of microendoscopic foraminotomy for lumbar foraminal stenosis and predicting surgical success. The 45.0% O/D complex occupancy cut-off value can guide patient selection and outcome prediction. These insights contribute to informed surgical decision-making and underscore the importance of evaluating the O/D complex in preoperative planning and predicting outcomes.

The muscle evoked potential after epidural electrical stimulation of the spinal cord as a monitor for the corticospinal tract: studies by collision technique and double train stimulation.

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.

Can postoperative deltoid weakness after cervical laminoplasty be prevented by using intraoperative neurophysiological monitoring?

Laminoplasty, frequently performed in patients with cervical myelopathy, is safe and provides relatively good results. However, motor palsy of the upper extremities, which occurs after decompression surgery for cervical myelopathy, often reduces muscle strength of the deltoid muscle, mainly in the C5 myotome. The aim of this study was to investigate prospectively whether postoperative deltoid weakness (DW) can be predicted by performing intraoperative neurophysiological monitoring (IONM) during cervical laminoplasty and to clarify whether it is possible to prevent palsy using IONM. We evaluated the 278 consecutive patients (175 males and 103 females) who underwent French-door cervical laminoplasty for cervical myelopathy under IONM between November 2008 and December 2016 at our hospital. IONM was performed using muscle evoked potential after electrical stimulation to the brain [Br(E)-MsEP] from the deltoid muscle. Seven patients (2.5%) developed DW after surgery (2 with acute and 5 with delayed onset). In all patients, deltoid muscle strength recovered to ≥ 4 on manual muscle testing 3-6 months after surgery. Persistent IONM alerts occurred in 2 patients with acute-onset DW. To predict the acute onset of DW, Br(E)-MsEP alerts in the deltoid muscle had both a sensitivity and specificity of 100%. The PPV of persistent Br(E)-MsEP alerts had both a sensitivity and specificity of 100% for acute-onset DW. There was no change in Br(E)-MsEP in patients with delayed-onset palsy. The incidence of deltoid palsy was relatively low. Persistent Br(E)-MsEP alerts of the deltoid muscle had a 100% sensitivity and specificity for predicting a postoperative acute deficit. IONM was unable to predict delayed-onset DW. In only 1 patient were we able to prevent postoperative DW by performing a foraminotomy.

Prevalence of Facet Effusion and Its Relationship with Lumbar Spondylolisthesis and Low Back Pain: The Wakayama Spine Study.

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.

MRI-defined paraspinal muscle morphology in Japanese population: The Wakayama Spine Study.

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.

Minimally invasive decompression surgery for lumbar spinal stenosis with degenerative scoliosis: Predictive factors of radiographic and clinical outcomes.

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.

Efficacy and safety of novel high-frequency multi-train stimulation for recording transcranial motor evoked potentials in a rat model.

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.

Classification of High Intensity Zones of the Lumbar Spine and Their Association with Other Spinal MRI Phenotypes: The Wakayama Spine Study.

INTRODUCTION: High intensity zones (HIZ) of the lumbar spine are a phenotype of the intervertebral disc noted on MRI whose clinical relevance has been debated. Traditionally, T2-weighted (T2W) magnetic resonance imaging (MRI) has been utilized to identify HIZ of lumbar discs. However, controversy exists with regards to HIZ morphology, topography, and association with other MRI spinal phenotypes. Moreover, classification of HIZ has not been thoroughly defined in the past and the use of additional imaging parameters (e.g. T1W MRI) to assist in defining this phenotype has not been addressed. MATERIALS AND METHODS: A cross-sectional study of 814 (69.8% females) subjects with mean age of 63.6 years from a homogenous Japanese population was performed. T2W and T1W sagittal 1.5T MRI was obtained on all subjects to assess HIZ from L1-S1. We created a morphological and topographical HIZ classification based on disc level, shape type (round, fissure, vertical, rim, and enlarged), location within the disc (posterior, anterior), and signal type on T1W MRI (low, high and iso intensity) in comparison to the typical high intensity on T2W MRI. RESULTS: HIZ was noted in 38.0% of subjects. Of these, the prevalence of posterior, anterior, and both posterior/anterior HIZ in the overall lumbar spine were 47.3%, 42.4%, and 10.4%, respectively. Posterior HIZ was most common, occurring at L4/5 (32.5%) and L5/S1 (47.0%), whereas anterior HIZ was most common at L3/4 (41.8%). T1W iso-intensity type of HIZ was most prevalent (71.8%), followed by T1W high-intensity (21.4%) and T1W low-intensity (6.8%). Of all discs, round types were most prevalent (anterior: 3.6%, posterior: 3.7%) followed by vertical type (posterior: 1.6%). At all affected levels, there was a significant association between HIZ and disc degeneration, disc bulge/protrusion and Modic type II (p<0.01). Posterior HIZ and T1W high-intensity type of HIZ were significantly associated with disc bulge/protrusion and disc degeneration (p<0.01). In addition, posterior HIZ was significantly associated with Modic type II and III. T1W low-intensity type of HIZ was significantly associated with Modic type II. CONCLUSIONS: This is the first large-scale study reporting a novel classification scheme of HIZ of the lumbar spine. This study is the first that has utilized T2W and T1W MRIs in differentiating HIZ sub-phenotypes. Specific HIZ sub-phenotypes were found to be more associated with specific MRI degenerative changes. With a more detailed description of the HIZ phenotype, this scheme can be standardized for future clinical and research initiatives.

The Association between the Cross-Sectional Area of the Dural Sac and Low Back Pain in a Large Population: The Wakayama Spine Study.

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.