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.

Comparison of the electrophysiological characteristics of tight filum terminale and tethered cord syndrome.

PURPOSE: This study aims to characterize tight filum terminale (TFT) in motor evoked potential (MEP) testing by comparing TFT patients with both tethered cord syndrome (TCS) patients and healthy subjects. METHODS: Fifty TFT patients, 18 TCS patients, and 35 healthy volunteers participated in this study. We recorded MEPs following transcranial magnetic stimulation from the bilateral abductor hallucis muscles as well as compound muscle action potentials and F-waves evoked by electrical stimulation of the tibial nerve from the bilateral abductor pollicis brevis muscles. The peripheral conduction time (PCT) was calculated from the latency of the compound action potential and F-wave. Furthermore, the central motor conduction time (CMCT) was calculated by subtracting PCT from MEP latency. RESULTS: TFT and TCS patients had a significantly longer MEP latency than healthy subjects. PCT in TFT patients was significantly longer than those in TCS patients or healthy subjects. Using the cutoff values for PCT, we were able to diagnose patients with TFT patients with a sensitivity of 72.0% and a specificity of 91.4%. CONCLUSION: Prolonged PCT in the MEP test may be a useful indicator for TFT and suggests that MEP may be used as an adjunct diagnostic tool for TFT.

Evaluation of intervertebral disc degeneration using T2 signal ratio on magnetic resonance imaging.

PURPOSE: Intervertebral disc degeneration is assessed clinically by magnetic resonance imaging (MRI). Although some quantitative evaluation methods for MRI under special imaging conditions have been reported, they are widely and generally difficult to use. The aim of this study is to determine if intervertebral disc degeneration can be assessed using the ratio of MRI T2 values of the disc to the spinal cord T2 values. METHODS: Signal ratio was calculated using the T2 signal intensity of the disc and the spinal cord on MRI under common conditions for a new assessment of disc degeneration. T2-weighted images of 100 patients undergoing MRI twice within a year under different imaging conditions, 1.5 T or less and 3.0 T, were used for the assessment. The T2 signal intensity was measured at the center of the discs at L2-3, L3-4, L4-5, L5-S1 and the spinal cord at T12 level. Signal ratio was calculated using these T2 signal intensity values. The ratio of the difference between the first and second values to the mean of the first and second values was calculated to confirm the equivalence of MRI assessments of disc degeneration in the same patient under different imaging conditions. RESULTS: The equivalence of values between the first MRI and the second MRI in the signal ratio was significantly higher than that in the T2 signal intensity. In addition, the signal ratio was negatively correlated with age and were significantly associated with Pfirrmann grade. CONCLUSIONS: By using the signal ratio, disc degeneration can be evaluated by MRI even under different imaging conditions.

Development of a rat model with lumbar vertebral endplate lesion.

PURPOSE: Vertebral endplate lesion (EPL) caused by severe disc degeneration is associated with low back pain. However, there is no suitable animal model to elucidate the pathophysiology of EPL. This study aimed to develop a rat model of EPL and evaluate rat behavior and imaging and histological findings. METHODS: The L4-5 intervertebral discs of Sprague-Dawley rats were transperitoneally removed, except for the outer annulus fibrosus and cartilage endplate, in the EPL group. The L4-5 discs were not removed and simply exposed in the sham group. Changes around the vertebral endplate on magnetic resonance imaging (MRI) and computed tomography (CT) were evaluated. Additionally, pain-related behavioral and histological assessments were performed. RESULTS: In the EPL group, a low-signal area around the vertebral endplate was observed on T1-weighted and T2-weighted fat-saturated MRI at 8 weeks or later after surgery. In the same group, CT showed osteosclerosis around the vertebral endplate at 12 weeks after surgery. The sham group did not show abnormal imaging features on the MRI and CT. Behavioral evaluation showed that the EPL group had a significantly longer grooming time than the sham group. Conversely, the 12-week postoperative locomotion time and the 1- and 12-week postoperative standing times were significantly shorter in the EPL group than in the sham group. Histological evaluation showed a high degree of vertebral endplate degeneration and an increased number of osteoclasts and proportion of nerve fibers expressing calcitonin gene-related peptide in the EPL group compared to those in the sham group. CONCLUSION: Our rat EPL model showed pain-related behavioral patterns and an increased expression of pain-related neuropeptide. This model could contribute to the study of the pathophysiology of EPL and will help in the treatment of low back pain in the future.

Quantifying Bone Marrow Edema Adjacent to the Lumbar Vertebral Endplate on Magnetic Resonance Imaging: A Cross-Sectional Study of Patients with Degenerative Lumbar Disease.

STUDY DESIGN: Cross-sectional study. PURPOSE: We aimed to quantitatively assess bone marrow edema (BME) on magnetic resonance imaging (MRI) for patients with degenerative lumbar diseases. OVERVIEW OF LITERATURE: BME adjacent to a sclerotic endplate of the lumbar spine, detected using T2-weighted fat-saturated MRI, is closely associated with low back pain in patients with degenerative lumbar diseases. However, currently, there no quantitative evaluation methods for BME adjacent to the vertebral endplate. METHODS: Patients with degenerative lumbar diseases, whose MRIs detected BME, were enrolled. On a T2-weighted fat-saturated MRI, BME appeared as a high-intensity region adjacent to the vertebral endplate. We calculated the contrast ratios (CRs) of BME and normal bone marrow using the signal intensities of BME, normal bone marrow, and the spinal cord. On computed tomography, we calculated Hounsfield unit (HU) values in the same area as BME, the sclerotic endplate, and normal bone marrow to assess bone density. RESULTS: There were 16 men and 14 women, with an average age of 73.5 years. The mean CRs of BME and normal bone marrow were -0.015±0.056 and -0.407±0.023, respectively. BME's CR was significantly higher than that of normal bone marrow (p<0.01). The HU values in the same area as BME, the sclerotic endplate, and normal bone marrow were 251.9±24.6, 828.3±35.6, and 98.1±9.3, respectively; these values were significantly different from each other (p<0.01). CONCLUSIONS: The CR on MRI is a useful quantitative assessment tool for BME in patients with degenerative lumbar diseases.

Surgical outcomes of cervical myelopathy in patients with athetoid cerebral palsy.

PURPOSE: Surgical treatment for cervical myelopathy with athetoid cerebral palsy remains unestablished. Instrumented fusion is reported to have good clinical results; however, there are no data of decompression surgery for this pathology in recent years. This study aimed to assess the surgical outcomes of laminoplasty with or without posterior instrumented fusion for cervical myelopathy in patients with athetoid cerebral palsy. METHODS: A multi-centre surgical series of patients with cervical myelopathy and athetoid cerebral palsy were enrolled in this study. All patients showed symptoms and signs suggestive of cervical myelopathy and underwent laminoplasty with or without instrumented fusion. The Japanese Orthopaedic Association (JOA) score, Barthel index (BI), and changes in the C2-C7 sagittal Cobb angle in the lateral plain radiograph were analysed. RESULTS: There were 25 patients (16 men and 9 women; mean age, 54.4 ± 10.8 years) with cervical myelopathy and athetoid cerebral palsy who underwent surgical treatment. The mean follow-up period was 41.9 ± 35.6 months. Overall, the BI significantly improved after surgery, whereas the JOA score and C2-C7 angle did not improve postoperatively. The recovery rate of the JOA score in the laminoplasty group was significantly higher than that of the fusion group (P = 0.02). CONCLUSIONS: Cervical laminoplasty with or without instrumented fusion for treating cervical myelopathy due to athetoid cerebral palsy is effective in improving activities of daily living. Cervical laminoplasty may be an effective and less invasive surgical method for selective patients, especially for those with small involuntary movements and no remarkable cervical kyphosis nor instability.

Long-term outcome of targeted therapy for low back pain in elderly degenerative lumbar scoliosis.

PURPOSE: Treatment of low back pain (LBP) associated with elderly degenerative lumbar scoliosis (DLS) remains controversial. We have developed percutaneous intervertebral-vacuum polymethylmethacrylate injection (PIPI) targeting to the intervertebral vacuum as a minimally invasive surgery. The present study compared the long-term clinical outcomes of PIPI to that of nonoperative treatment. METHODS: Patients with de novo DLS, aged ≥ 65 years, who had LBP with visual analog scale (VAS) of ≥ 50 for ≥ 6 months with intervertebral vacuum on computed tomography and bone marrow edema (BME) on magnetic resonance imaging were included. The clinical outcomes were evaluated using VAS and the Oswestry Disability Index (ODI) at baseline, 1, 6, 12, 24 months, and at the final follow-up. The course of BME was also evaluated. RESULTS: One hundred and one patients underwent PIPI and 61 received nonoperative treatment. The mean follow-up duration after PIPI and nonoperative treatment was 63.7 ± 32.4 and 43.9 ± 20.9 months, respectively. VAS and ODI after PIPI were significantly improved compared to post-nonoperative treatment. BME decreased substantially in the PIPI group and it was significantly correlated with VAS and ODI improvement. Following PIPI, LBP recurred in 28 patients (35%). LBP recurrence was identified at the same level of PIPI in 10 patients, at the adjacent level of PIPI in 11 patients, and at the non-adjacent level of PIPI in seven patients. Eighteen patients underwent additional PIPIs, and both VAS and ODI were significantly improved after additional PIPIs. CONCLUSION: Bone marrow lesions of the endplate are strongly associated with the presence of LBP. PIPI can be considered as an effective, safe and repeatable treatment for LBP in elderly DLS patients.