Skeletal muscle injury treatment using the Silk Elastin® injection in a rat model.

Background: Skeletal muscle injury (SMI) is often treated conservatively, although it can lead to scar tissue formation, which impedes muscle function and increases muscle re-injury risk. However, effective interventions for SMIs are yet to be established. Hypothesis: The administration of Silk Elastin® (SE), a novel artificial protein, to the SMI site can suppress scar formation and promote tissue repair. Study design: A controlled laboratory study. Methods: In vitro: Fibroblast migration ability was assessed using a scratch assay. SE solution was added to the culture medium, and the fibroblast migration ability was compared across different concentrations. In vivo: An SMI model was established with Sprague-Dawley rats, which were assigned to three groups based on the material injected to the SMI site: SE gel (SE group; n = 8), atelocollagen gel (Atelo group; n = 8), and phosphate buffer saline (PBS group; n = 8). Histological evaluations were performed at weeks 1 and 4 following the SMI induction. In the 1-week model, we detected the expression of transforming growth factor (TGF)-ß1 in the stroma using immunohistological evaluation and real-time polymerase chain reaction analysis. In the 4-week model, we measured tibialis anterior muscle strength upon peroneal nerve stimulation as a functional assessment. Results: In vitro: The fibroblast migration ability was suppressed by SE added at a concentration of 104 µg/mL in the culture medium. In vivo: In the 1-week model, the SE group exhibited significantly lower TGFß -1 expression than the PBS group. In the 4-week model, the SE group had a significantly larger regenerated muscle fiber diameter and smaller scar formation area ratio than the other two groups. Moreover, the SE group was superior to the other two groups in terms of regenerative muscle strength. Conclusion: Injection of SE gel to the SMI site may inhibit tissue scarring by reducing excessive fibroblast migration, thereby enhancing tissue repair. Clinical relevance: The findings of this study may contribute to the development of an early intervention method for SMIs.

Differentiation of the Intradural Extramedullary Spinal Tumors, Schwannomas, and Meningiomas Utilizing the Contrast Ratio as a Quantitative Magnetic Resonance Imaging Method.

BACKGROUND: Schwannomas and meningiomas are the most common intradural extramedullary spinal tumors; however, differentiating between them using magnetic resonance imaging (MRI) is a frequent challenge. In this study, we aimed to investigate the use of the contrast ratio (CR) as a quantitative MRI method in the differentiation of schwannomas and meningiomas. METHODS: We analyzed the data of patients with intradural extramedullary spinal tumors who underwent surgery and were diagnosed with either schwannomas or meningiomas by histopathological analysis. Regions of interest were set for the entire spinal tumor on T2-weighted sagittal MRI. To obtain the CR values of spinal tumors (CRtumor), we used the signal intensity (SI) values of the tumor (SItumor) and spinal cord (SIcord) according to the following formula: [CRtumor = (SItumor-SIcord)/(SItumor+SIcord)]. RESULTS: The study included 50 patients (23 males and 27 females) with a mean age of 61.5 years old (11-85 years old). Histopathological analysis revealed that 33 and 17 patients were diagnosed with schwannomas and meningiomas, respectively. The mean CR values of the schwannomas and meningiomas were 0.3040 ± 0.1386 and 0.0173 ± 0.1929, respectively. The CR value of the schwannomas was statistically significantly higher than that of meningiomas (P < 0.01). The cutoff CR value obtained from the receiver operating characteristic curve was 0.143, with a specificity and sensitivity of 90.9% and 88.2%, respectively. Furthermore, the value for the area under the receiver operating characteristic curve was 0.925 (95% confidence interval: 0.852-0.998). CONCLUSIONS: The evaluation of CRs by using MRI to distinguish between schwannomas and meningiomas is a beneficial quantitative tool.

Myelin-Specific microRNA-23a/b Cluster Deletion Inhibits Myelination in the Central Nervous System during Postnatal Growth and Aging.

Microribonucleic acids (miRNAs) comprising miR-23a/b clusters, specifically miR-23a and miR-27a, are recognized for their divergent roles in myelination within the central nervous system. However, cluster-specific miRNA functions remain controversial as miRNAs within the same cluster have been suggested to function complementarily. This study aims to clarify the role of miR-23a/b clusters in myelination using mice with a miR-23a/b cluster deletion (KO mice), specifically in myelin expressing proteolipid protein (PLP). Inducible conditional KO mice were generated by crossing miR-23a/b clusterflox/flox mice with PlpCre-ERT2 mice; the offspring were injected with tamoxifen at 10 days or 10 weeks of age to induce a myelin-specific miR-23a/b cluster deletion. Evaluation was performed at 10 weeks or 12 months of age and compared with control mice that were not treated with tamoxifen. KO mice exhibit impaired motor function and hypoplastic myelin sheaths in the brain and spinal cord at 10 weeks and 12 months of age. Simultaneously, significant decreases in myelin basic protein (MBP) and PLP expression occur in KO mice. The percentages of oligodendrocyte precursors and mature oligodendrocytes are consistent between the KO and control mice. However, the proportion of oligodendrocytes expressing MBP is significantly lower in KO mice. Moreover, changes in protein expression occur in KO mice, with increased leucine zipper-like transcriptional regulator 1 expression, decreased R-RAS expression, and decreased phosphorylation of extracellular signal-regulated kinases. These findings highlight the significant influence of miR-23a/b clusters on myelination during postnatal growth and aging.

Development of a novel animal model of lumbar vertebral endplate lesion by intervertebral disk injection of monosodium iodoacetate in rats.

PURPOSE: Vertebral endplate lesions (EPLs) caused by severe disk degeneration are associated with low back pain. However, its pathophysiology remains unclear. In this study, we aimed to develop a vertebral EPL rat model mimicking severe intervertebral disk (IVD) degeneration by injecting monosodium iodoacetate (MIA) into the IVDs and evaluating it by assessing pain-related behavior, micro-computed tomography (CT) findings, and histological changes. METHODS: MIA was injected into the L4-5 and L5-6 IVDs of Sprague-Dawley rats. Their behavior was examined by measuring the total distance traveled and the total number of rearing in an open square arena. Bone alterations and volume around the vertebral endplate were assessed using micro-CT. Safranin-O staining, immunohistochemistry, and tartrate-resistant acid phosphatase (TRAP) staining were performed for histological assessment. RESULTS: The total distance and number of rearing times in the open field were significantly reduced in a time-dependent manner. Micro-CT revealed intervertebral osteophytes and irregularities in the endplates at 12 weeks. The bone volume/tissue volume (BV/TV) around the endplates significantly increased from 6 weeks onward. Safranin-O staining revealed severe degeneration of IVDs and endplate disorders in a dose- and time-dependent manner. Calcitonin gene-related peptide-positive nerve fibers significantly increased from 6 weeks onward. However, the number of osteoclasts decreased over time. CONCLUSION: Our rat EPL model showed progressive morphological vertebral endplate changes in a time- and concentration-dependent manner, similar to the degenerative changes in human IVDs. This model can be used as an animal model of severe IVD degeneration to better understand the pathophysiology of EPL.

Evaluation of Epiconus and Conus Medullaris Disorders due to Thoracolumbar Vertebral Fracture using Motor Evoked Potentials.

STUDY DESIGN: A retrospective case-control study. OBJECTIVE: To characterize the motor evoked potential (MEP) when the epiconus or conus medullaris is compressed by a fracture of the T12 or L1 vertebra. SUMMARY OF BACKGROUND DATA: Although the characteristics of compressive cervical and thoracic myelopathy with transcranial magnetic stimulation MEP have been reported, the MEP parameters in compressive disorders of the epiconus and conus medullaris have not yet been characterized. METHODS: Twenty patients with T12 or L1 vertebral fractures who had lower extremity symptoms due to compression of the epiconus or conus medullaris were included. These patients were compared with 28 healthy controls and 32 patients with cervical spondylotic radiculopathy (CSR) without spinal cord compression. MEPs of abductor hallucis muscles were recorded using transcranial magnetic stimulation and electrical stimulation of the tibial nerve. MEP latency, central motor conduction time (CMCT), and peripheral conduction time (PCT) were evaluated. RESULTS: MEP latency, CMCT, and PCT were significantly longer in patients with fractures than in healthy controls and patients with CSR. MEP latency was most accurate for differentiating patients with fracture from healthy controls (cutoff value, 40.0 ms, sensitivity, 95.0%; specificity, 100%), and CMCT was most accurate for comparing patients with fracture and CSR (cutoff value, 15.5 ms, sensitivity, 80.0%; specificity, 93.8%). In the distinction between patients with fracture and CSR, 16 of the 20 patients with fracture exceeded the cutoff values for any of the parameters, and 12 of them exceeded the cutoff values for all parameters. There was no significant correlation between the linear distance from the most inferior end of the spinal cord to the site of compression and any of the MEP parameters. CONCLUSION: Both CMCT and PCT are often prolonged in compressive lesions of the epiconus and conus medullaris, and MEP latency and CMCT are useful in the diagnosis.

Short-segment spinal fusion for chronic low back pain with bone marrow edema adjacent to the vertebral endplate in adult spinal deformity.

PURPOSE: Corrective long spinal fusion is a widely accepted surgical method for patients with adult spinal deformities. However, instrumented long fusion is associated with a significant risk of complications. Therefore, we aimed to assess the success of short-segment spinal fusion, particularly for bone marrow edema (BME) adjacent to the vertebral endplate, in patients with low back pain (LBP) and spinal deformity. METHODS: A prospective study was performed at multiple hospitals wherein we monitored patients with spinal deformities and accompanying LBP. Patients aged ≥ 50 years with a minimum LBP severity score of 40 mm on the visual analog scale (VAS) were included in the study. We also included patients with lumbar BME on magnetic resonance imaging. Short spinal fusion was performed on segments with BME. Clinical evaluations of LBP on VAS and Oswestry Disability Index (ODI), and radiological parameters for sagittal vertical axis (SVA), pelvic incidence (PI), lumbar lordosis (LL) and pelvic tilt (PT) were carried out. RESULTS: Overall, 35 patients (22 men and 13 women), with a mean age of 66.7 years and a mean follow-up period of 32 months, were included in the study. The mean VAS and ODI scores were 72.4 mm and 49.0% before surgery and 25.5 mm and 29.9% at the final follow-up, respectively; these parameters significantly improved after surgery. The SVA, PI-LL, and PT scores were 70.1 mm, 20.9°, and 22.8° before surgery and 85.4 mm, 13.8°, and 22.7° at the final follow-up, respectively. The spinal alignment parameters did not change significantly after surgery. CONCLUSIONS: Short-segment spinal fusion is effective for treating LBP and spinal deformity with BME adjacent to the vertebral endplate without spinal correction.

Intradiscal Condoliase Injection Therapy for Recurrent Lumbar Disc Herniation: Case Series and Literature Review.

Background and objectives: Although chemonucleolysis with condoliase for lumbar disc herniation (LDH) has become common, few reports have described its application in the treatment of recurrent LDH. Therefore, this study aimed to evaluate the safety and efficacy of condoliase treatment in six patients with recurrent LDH and review the available literature on condoliase treatment for LDH. Materials and Methods: Six patients (four men and two women; mean age, 64.7 years) with recurrent LDH who were treated with condoliase at our hospital between 2019 and 2022 were included. The clinical records and images of the patients were retrospectively evaluated. In addition, the available English literature on condoliase treatment for LDH was retrieved and reviewed. Results: Among the six patients included in the study, three showed >50% improvement in leg pain after treatment, which is a lower efficacy rate than that in previous reports. In addition, two patients required surgery after treatment, which is a higher rate than that in previous reports. The mean intervertebral disc height significantly decreased from 8.4 mm before treatment to 6.9 mm after treatment, consistent with the results of previous studies. None of the cases showed Modic type I changes on magnetic resonance imaging. Conclusions: Although the efficacy of condoliase treatment for recurrent LDH may be lower than that for primary LDH, this treatment was found to be safe and applicable for recurrent LDH.

Sacral Stress Fracture in Athletes With Overuse: A Clinical Series of 11 Patients and Literature Review.

STUDY DESIGN: This was a narrative review. OBJECTIVES: The purpose of this study was to report the physical and radiologic characteristics of sacral stress fractures in 11 athletes and to review the current literature on sacral stress fractures. SUMMARY OF BACKGROUND DATA: Sacral stress fractures are rarely reported as a cause of low back pain in athletes. PATIENTS AND METHODS: We retrospectively analyzed 11 athlete patients with sacral stress fractures and low back pain. All patients received conservative treatments, such as rest from sporting activities and physical therapy. Clinical data, such as age, sex, athletic activity, region of tenderness, and duration of low back pain, and radiologic data, such as information from plain radiographs and fracture lines on magnetic resonance imaging (MRI), were evaluated. RESULTS: The study included 11 athlete patients (5 males and 6 females) with sacral stress fractures, and their mean age was 18.7 years (range, 15-38 y). The sports that caused the stress fractures were baseball, badminton, and basketball in 2 patients each and football, judo, marathon, volleyball, and dance in 1 patient each. All patients had tenderness on the sacrum. The mean duration of low back pain was 1.8 weeks (range, 1-4 wk). Fracture lines on MRI were observed only in the caudal-ventral part of the sacrum in 7 patients and extended from the inferolateral angle of the sacrum to the superior lateral sacral alar in 4 patients. CONCLUSIONS: The study findings demonstrated that MRI and tenderness were useful for detecting the presence of sacral stress fractures in athletes. Moreover, fracture lines in the sacrum may progress from the caudal-ventral part of the sacrum to the cranio-dorsal direction.

Physical Signs and Clinical Features of Cervical Myelopathy in Elderly Patients, Especially 80 Years or Older: Comparison of 100 Consecutive Operative Cases across Three Age Groups.

STUDY DESIGN: Retrospective cohort study. PURPOSE: The present study aimed to examine the characteristics of physical signs in elderly patients with cervical myelopathy (CM) and to compare the findings in three different age groups. OVERVIEW OF LITERATURE: As the global population ages, the incidence of CM in elderly patients is increasing. METHODS: We evaluated 100 consecutive surgical patients with CM and divided them into the following groups: 80s (34 patients; mean age, 83.9 years), 70s (33 patients; mean age, 73.9 years), and 69 or younger (33 patients; mean age, 60.9 years). The clinical symptoms and physical signs were evaluated and recorded. RESULTS: Although the recovery rate decreased with increasing age, all groups demonstrated a significant improvement in clinical symptoms relative to preoperative values. The Hoffman sign and hyperreflexia of the triceps tendon were, respectively, present in 82% and 88% of patients in the 80s group, 74% and 64% of those in the 70s group, and 69% and 82% of those in the 69 or younger group, with no significant difference among the groups. In contrast, the rates of hyperreflexia of the patellar and Achilles tendons were, respectively, 59% and 32% in the 80s group, 85% and 48% in the 70s group, and 91% and 70% in the 69 or younger group, with significant differences. CONCLUSIONS: The positivity rate of the lower extremity hyperreflexia decreased significantly with increasing age in patients with CM. The absence of hyperreflexia, particularly lower extremity, is not uncommon in elderly patients with suspected CM.

Immediate Closed Reduction Technique for Cervical Spine Dislocations.

STUDY DESIGN: Retrospective study. PURPOSE: This research aimed to assess the clinical outcomes of patients with traumatic cervical spine dislocation who underwent closed reduction employing our approach. OVERVIEW OF LITERATURE: Bedside closed reduction is the quickest procedure for repairing traumatic cervical spine dislocations; nevertheless, it also possesses the risk of neurological deterioration. METHODS: For closed reduction, the patient's head was elevated on a motorized bed, the cervical spine was placed at the midline, traction of 10 kg was applied, the motorized bed was gradually returned to a flat position, the head was lifted off the bed, and the cervical spine was slowly adjusted to a flexed position. The weight of traction was elevated by 5-kg increments until the positional shift was attained. Subsequently, the bed was gradually tilted while traction was applied again to return the cervical spine to the midline position. RESULTS: Of the 43 cases of cervical spine dislocation, closed reduction was carried out in 40 cases, of which 36 were successful. During repositioning, three patients experienced a temporary worsening of their neck pain and neurological symptoms that enhanced when the cervical spine was flexed. Closed reduction was conducted while the patient was awake; nevertheless, sedation was needed in three cases. Among the 24 patients whose pretreatment paralysis had been characterized by American Spinal Injury Association Impairment Scale (AIS) grades A-C, seven patients (29.2%) demonstrated an enhancement of two or more AIS grades at the last observation. CONCLUSIONS: Our closed reduction approach safely repaired traumatic cervical spine dislocations.

Balancing ability of patients with lumbar spinal canal stenosis.

PURPOSE: To determine the relationship between postural sway and the severity of lumbar spinal canal stenosis as well as the effect on postoperative improvement. METHODS: Stabilometry was performed before and 6 months after surgery in 52 patients (29 men and 23 women; mean age, 74.1 ± 7.8 years) who underwent decompression surgery for lumbar spinal canal stenosis. The environmental area (EA; the area surrounding the circumference of the stabilogram) and locus length per EA (L/EA) were evaluated. The patients were divided into moderate (n = 22) and severe (n = 30) groups according to the severity of canal stenosis. Patient characteristics and parameters were compared between the groups before and after surgery, including the visual analog scale (VAS) score for leg pain, Oswestry Disability Index (ODI), EA, and L/EA. In addition, factors affecting EA and L/EA were evaluated using multiple regression analysis. RESULTS: Age (p = 0.031), preoperative EA (p < 0.001), preoperative L/EA (p = 0.032), and sagittal vertical axis (p = 0.033) were significantly different between groups. The VAS score and ODI significantly improved postoperatively in both groups (p < 0.001). The EA significantly improved postoperatively only in the severe group (p < 0.001), whereas the L/EA did not significantly improve in either group. Multiple regression analysis showed that only the severity of canal stenosis was significantly associated with preoperative EA (p = 0.030), whereas age (p = 0.040) and severity of canal stenosis (p = 0.030) were significantly associated with preoperative L/EA. Diabetes was significantly associated with postoperative EA (p = 0.046) and L/EA (p = 0.030). CONCLUSION: The severity of canal stenosis affected abnormal postural sway, which improved after decompression surgery.

Vertebral osteomyelitis due to Mycobacterium abscessus subsp. massiliense with paravertebral abscess: A case report and review.

The incidence of vertebral osteomyelitis (VO) caused by non-tuberculosis mycobacteria (NTM) without immunocompetence is extremely rare. Herein, we reported on a case of VO caused by NTM. A 38-year-old man was admitted to our hospital with persisting low back and leg pain which had lasted for a year. Before coming to our hospital, the patient was treated with antibiotics and iliopsoas muscle drainage. The biopsy confirmed the presence of a NTM, Mycobacterium abscessus subsp. massiliense. Several tests were conducted which showed the infection had progressively increased, such as vertebral endplate destruction on plain radiography, computed tomography scan, and epidural and paraspinal muscle abscesses on magnetic resonance imaging. The patient underwent radical debridement, anterior intervertebral fusion with bone graft, and posterior instrumentation with antibiotic administration. A year later, the patient's low back and leg pain was relieved without any analgetic. VO due to NTM is rare but can be treated with multimodal therapy.

Differentiating Neurodegenerative Disease from Compressive Cervical Myelopathy Using Motor Evoked Potentials.

STUDY DESIGN: A retrospective case-control study. OBJECTIVE: To differentiate neurodegenerative diseases from compressive cervical myelopathy (CCM) using motor evoked potentials (MEPs). SUMMARY OF BACKGROUND DATA: When considering surgery for CCM, it may be necessary to differentiate the condition from a neurodegenerative disease. METHODS: A total of 30 healthy volunteers, 52 typical CCM patients with single-level compression of the spinal cord at C4-5 or C5-6, seven patients with amyotrophic lateral sclerosis (ALS), and 12 patients with demyelinating disease of the central nervous system (DDC), including 11 patients with multiple sclerosis and one patient with neuromyelitis optica spectrum disorder, formed our study population. MEPs were recorded from the bilateral abductor digiti minimi (ADM) and abductor hallucis (AH) muscles using transcranial magnetic stimulation and electrical stimulation of the ulnar and tibial nerves. Central motor conduction time (CMCT), peripheral conduction time, amplitude of MEPs, and frequency of F-waves were evaluated. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off value for distinguishing between CCM and ALS. RESULTS: Significant differences were observed in the amplitude of MEPs and frequency of F-waves evoked by peripheral nerve stimulation between patients with CCM and ALS. The MEP amplitude of AH was more accurate in differentiating between the two diseases compared to ADM (cut-off value, 11.2mV, sensitivity, 87.5%; specificity, 85.7%). All seven patients with ALS showed reduced frequency of F waves from ADM or AH, but none of the healthy volunteers or patients with other diseases demonstrated this finding. Moreover, there were no significant differences between CCM and DDC in any of the assessments. CONCLUSION: The amplitude of MEPs and frequency of F waves evoked by peripheral nerve stimulation could be helpful in differentiating ALS from CCM.

Deficiency of MicroRNA-23-27-24 Clusters Exhibits the Impairment of Myelination in the Central Nervous System.

Several microRNAs (miRNAs), including miR-23 and miR-27a have been reportedly involved in regulating myelination in the central nervous system. Although miR-23 and miR-27a form clusters in vivo and the clustered miRNAs are known to perform complementary functions, the role of these miRNA clusters in myelination has not been studied. To investigate the role of miR-23-27-24 clusters in myelination, we generated miR-23-27-24 cluster knockout mice and evaluated myelination in the brain and spinal cord. Our results showed that 10-week-old knockout mice had reduced motor function in the hanging wire test compared to the wild-type mice. At 4 weeks, 10 weeks, and 12 months of age, knockout mice showed reduced myelination compared to wild-type mice. The expression levels of myelin basic protein and myelin proteolipid protein were also significantly lower in the knockout mice compared to the wild-type mice. Although differentiation of oligodendrocyte progenitor cells to oligodendrocytes was not inhibited in the knockout mice, the percentage of oligodendrocytes expressing myelin basic protein was significantly lower in 4-week-old knockout mice than that in wild-type mice. Proteome analysis and western blotting showed increased expression of leucine-zipper-like transcription regulator 1 (LZTR1) and decreased expression of R-RAS and phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2) in the knockout mice. In summary, loss of miR-23-27-24 clusters reduces myelination and compromises motor functions in mice. Further, LZTR1, which regulates R-RAS upstream of the ERK1/2 pathway, a signal that promotes myelination, has been identified as a novel target of the miR-23-27-24 cluster in this study.

Prognostic factors of balloon kyphoplasty for osteoporotic vertebral fractures with diffuse idiopathic skeletal hyperostosis.

OBJECTIVE: The authors aimed to determine the poor prognostic factors of balloon kyphoplasty for the treatment of fractures of the most distal or distal-adjacent vertebrae in ankylosing spines with diffuse idiopathic skeletal hyperostosis (DISH). METHODS: Eighty-nine patients with fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH were included and divided into two groups: those with (n = 51) and without (n = 38) bone healing 6 months postoperatively. Clinical evaluation included age, sex, time from onset to surgery, the visual analog scale score for low-back pain, and the Oswestry Disability Index (ODI). The VAS scores and ODI were measured both preoperatively and at 6 months postoperatively. Radiological evaluations included bone density; wedge angles of the fractured vertebrae in the supine and sitting positions on lateral radiographs; differences in the wedge angles (change in wedge angle); and the amount of polymethylmethacrylate used. RESULTS: The preoperative ODI, vertebral wedge angles in the supine and sitting positions, change in wedge angle, and amount of polymethylmethacrylate were significantly different between the two groups and were significantly associated with delayed bone healing in univariate logistic regression analysis. Multivariate logistic regression analysis showed that only a change in the wedge angle was significantly associated with delayed healing, with a cutoff value of 10°, sensitivity of 84.2%, and specificity of 82.4%. CONCLUSIONS: Treatment with balloon kyphoplasty alone should be avoided in patients with a difference ≥ 10° in the wedge angle of the fractured vertebrae between the supine and sitting positions.

Differentiation Between Compressive Cervical and Thoracic Myelopathy Using the Central Motor Conduction Time Ratio.

PURPOSE: Thoracic myelopathy is a rare condition whose diagnosis is often missed or delayed. This study aimed to differentiate between cervical and thoracic myelopathy using motor-evoked potential testing. METHODS: The authors included 835 patients with compressive cervical myelopathy and 94 patients with compressive thoracic myelopathy. Myelopathy using motor-evoked potentials were recorded from the bilateral abductor digiti minimi and abductor hallucis muscles through transcranial magnetic stimulation. The peripheral conduction time was measured through electrical stimulation of the ulnar and tibial nerves; moreover, the central motor conduction time (CMCT) was calculated by subtracting the peripheral conduction time from the myelopathy using motor-evoked potential latency. RESULTS: The most accurate differentiation between compressive cervical myelopathy and compressive thoracic myelopathy was achieved by the CMCT ratios (CMCT-ADM:CMCT-AH; cutoff value of 0.490, sensitivity of 83.0%, and specificity of 80.5%). After excluding patients with compressive cervical myelopathy who had spinal cord compression at C6-7, the cutoff value was 0.490, with a sensitivity of 83.0% and specificity of 87.3%. CONCLUSIONS: Determining the CMCT ratio (cutoff value of 0.490) through motor-evoked potential testing could facilitate differentiation between compressive cervical myelopathy and compressive thoracic myelopathy.

Microcervical Foraminotomy for Cervical Juxtafacet Cysts: Case Series and Literature Review.

BACKGROUND: Juxtafacet cysts are located near or contiguous with the facet joints, and their occurrence is rare in the cervical spine. We report 4 cases of cervical juxtafacet cysts operated by microcervical foraminotomy (MCF) or a combination of MCF and laminoplasty. We simultaneously review previously reported cases in terms of location, clinical findings, and surgical technique. METHODS: Among the patients who underwent spine surgery at our hospital from 2015 to 2019, 4 had cervical juxtafacet cysts. The images and clinical records of the patients were retrospectively assessed. Relevant previous English literature was searched and reviewed using PubMed. RESULTS: In our series, all 4 patients presented with unilateral upper extremity muscle weakness preoperatively. Two patients underwent MCF, and the other 2 underwent a combination of MCF and laminoplasty with resection of the cyst. All showed improvement in muscle strength. In previously reported cases, the rate of muscle weakness was high. A review of previous cases showed that 75 of 139 patients had cysts at C7-T1. The most common surgical techniques consisted of a hemilaminectomy or laminectomy with the addition of posterior fusion in 28 patients. The number of male patients was twice that of female patients; however, the male-to-female ratio was almost the same in patients with cysts in C7-T1. On pathological diagnosis, there were 3 times more synovial cysts than ganglion cysts. The percentage of synovial cysts was higher in patients with radiculopathy, and the percentage of ganglion cysts was higher in patients with myelopathy. CONCLUSIONS: Cervical juxtafacet cysts tend to occur in C7-T1 and cause muscle weakness. Surgical therapy is strongly recommended due to good postoperative improvement. CLINICAL RELEVANCE: The results of this study suggest that microcervical foraminotomy for cervical juxtafacet cysts can provide favorable symptomatic improvement.

Foramen Magnum Decompression with Outer Dura Matter Layer Resection for Chiari Type I Malformation: Factors Correlated with Syrinx Reduction.

STUDY DESIGN: A retrospective cohort study. PURPOSE: We aimed to investigate the surgical results of foramen magnum decompression (FMD) to identify the potential factors associated with syrinx reduction in Chiari malformation type I (CMI). OVERVIEW OF LITERATURE: The predictive value of preoperative factors for syrinx reduction in patients with CMI remains debatable. METHODS: We enrolled patients who underwent microscopic FMD with outer dural layer resection for CMI. The distance from the tip of the cerebellar tonsil to the C2 vertebral endplate on sagittal magnetic resonance imaging (MRI) was defined as the tonsillar distance (TD). Patients who showed a >20% syrinx diameter reduction on the 1-year follow-up MRI were defined as the syrinx reduction group while the others were categorized in the syrinx nonreduction group. Patients with syringomyelia were categorized into the clinically improved and unimproved groups using the Chicago Chiari Outcome Scale. The imaging and clinical parameters were evaluated pre- and postoperatively. RESULTS: This study included 25 patients of whom 19 (76.0%) had syringomyelia. At the 1-year follow-up, the syrinx diameter had decreased in 11 patients (57.8%). The increased TD significantly differed between the syrinx reduction and nonreduction groups. At the 1-year follow-up, 12 and seven patients with syringomyelia were categorized into the clinically improved and unimproved groups, respectively. The clinically improved and unimproved groups showed significant differences in the mean age and increased TD. CONCLUSIONS: Postoperative syrinx reduction was significantly correlated with the upward shifting of the cerebellar tonsil in patients with CMI. Our quantitative evaluation of the alterations in hindbrain position after FMD was easily performed and reflects the clinical outcomes.

Differences between spinal cord injury and cervical compressive myelopathy in intramedullary high-intensity lesions on T2-weighted magnetic resonance imaging: A retrospective study.

Increases in aging populations have raised the number of patients with cervical spinal cord injury (SCI) without fractures due to compression of the cervical spinal cord. In such patients, it is necessary to clarify whether SCI or cervical compressive myelopathy (CCM) is the cause of disability after trauma. This study aimed to clarify the differences in magnetic resonance imaging (MRI) features between SCI and CCM. Overall, 60 SCI patients and 60 CCM patients with intramedullary high-intensity lesions on T2-weighted MRI were included in this study. The longitudinal lengths of the intramedullary T2 high-intensity lesions were measured using sagittal MRI sections. Snake-eye appearance on axial sections was assessed as a characteristic finding of CCM. The T2 values of the high-intensity lesions and normal spinal cords at the first thoracic vertebra level were measured, and the contrast ratio was calculated using these values. The longitudinal length of T2 high-intensity lesions was significantly longer in SCI patients than in CCM patients. Snake-eye appearance was found in 26 of the 60 CCM patients, but not in SCI patients. On both the sagittal and axial images, the contrast ratio was significantly higher in the SCI group than in the CCM group. Based on these results, a diagnostic scale was created. This scale made it possible to distinguish between SCI and CCM with approximately 90% accuracy.