Yoichi Aota

A Novel Rabbit Model of Mild, Reproducible Disc Degeneration by an Anulus Needle Puncture : Correlation Between the Degree of Disc Injury and Radiological and Histological Appearances of Disc Degeneration

Study Design. An in vivo study to radiographically and histologically assess a new method of induction of disc degeneration. Objective. To establish a reproducible rabbit model of disc degeneration by puncturing the anulus with needles of defined gauges and to compare it to the classic stab model. Summary of Background Data. New treatment approaches to disc degeneration are of great interest. Although animal models for disc degenerative disease exist, the quantitative measurement of disease progression remains difficult. A reproducible, progressive disc degeneration model, which can be induced in a reasonable time frame, is essential for development of new therapeutic interventions. Methods. The classic anular stab model and the new needle puncture model were used in the rabbit. For the needle puncture model, 3 different gauges of needle (16G, 18G, and 21G) were used to induce an injury to the disc to a depth of 5 mm. Radiographic and histologic analyses were performed; magnetic resonance images were also assessed in the needle puncture model. Results. Significant disc space narrowing was observed as early as 2 weeks after stabbing in the classic stab model; there was no further narrowing of the disc space. In the needle puncture model, all needle sizes tested induced a slower and more progressive decrease in disc height than in the classic stab model. The magnetic resonance imaging supported the results of disc height data. Conclusions. The needle puncture approach, using 16G to 21G needles, resulted in a reproducible decrease of disc height and magnetic resonance imaging grade. The ease of the procedure and transfer of the methodology will benefit researchers studying disc degeneration.

Microdiscectomy and second operation for lumbar disc herniation

To prevent recurrence and avoid the second operation, the authors analyzed the clinical features and surgical outcome of 214 patients (157 males and 57 females) who underwent lumbar microdiscectomy, 16 of whom required second operation. The mean age was 34.6 years (range, 12-62 years). The average follow-up period was 4 years 5 months. The overall incidence of second operation was 7.5%. Second operation was performed because of recurrence of herniation in nine patients, and residual bony compression at the lateral recess in two. The incidence of second operation was significantly higher in teenagers than in patients in other age decades (P < 0.01), and in patients with protrusion-type herniation than in those with extrusion-type or sequestration-type herniation (P < 0.01). To prevent the necessity for second operation, careful and thorough discectomy, especially deep to the posterior longitudinal ligament, and decompression at the lateral recess are useful.

Magnetic Resonance Imaging and Magnetic Resonance Myelography in the Presurgical Diagnosis of Lumbar Foraminal Stenosis

Study Design. Retrospective case series with a control group. Objective. To measure the diagnostic performance of magnetic resonance imaging (MRI) and MR myelography (MRM) for symptomatic foraminal stenosis in patients who need surgery. Summary of Background Data. MR images are extensively used in the evaluation of foraminal stenosis and are often used to evaluate nerves exiting from the foramen. There has been no published report of the diagnostic performance of these imaging methods (MRI and MRM). Methods. Diagnostic performances were studied in 90 patients in whom the site of the stenosis was confirmed by means of selective decompression surgeries. The disease prevalence among patients was 26% (23 of 90 patients). The disease prevalence among foramens was 3% (25 of 936 foramens). The prevalence of abnormal findings in 27 asymptomatic volunteers was also studied. Two blinded observers interpreted foraminal narrowing on combinations of sagittal and axial MR images, abnormalities of the course of the nerve root in the foramen, and spinal nerve swelling on MRM. Results. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI for the diagnosis of symptomatic foraminal stenosis were 96%, 67%, 4%, and 100%, respectively. The corresponding values for abnormal nerve root course on MRM were 96%, 83%, 7%, and 100%, respectively, and for spinal nerve swelling on MRM were 60%, 99%, 35%, and 99%, respectively. Conclusions. Compared with conventional MRI, MRM affords more specific information for the presurgical diagnosis of symptomatic foraminal stenosis.

A ganglion cyst in the lumbar spinal canal : a case report

There have been some reports of ganglion cysts in the spinal canal in the English language medical literature, but no previous reports of an intraspinal extradural ganglion cyst shown on magnetic resonance images (MRI).

Differential effects of fibronectin fragment on proteoglycan metabolism by intervertebral disc cells: a comparison with articular chondrocytes.

Study Design. This in vitro study used the alginate bead culture system to probe for differences in the effects of fibronectin fragment on cell proliferation and proteoglycan metabolism by different populations of intervertebral disc cells and articular chondrocytes. Objective. To compare the effects of fibronectin fragment on cell proliferation, and proteoglycan synthesis and degradation by cells from the nucleus pulposus, the anulus fibrosus, and articular cartilage. Summary of Background Data. In articular cartilage, the administration of fibronectin fragment stimulates cartilage degeneration. Fibronectin fragment levels were increased in human intervertebral discs with increased disc degeneration. Fibronectin fragment injected into the central region of the rabbit intervertebral disc induced a progressive degeneration of that disc. Methods. Bovine tails and metacarpophalangeal joints from 14- to 18-month-old animals were used. Alginate beads containing cells isolated from intervertebral discs and articular cartilage were cultured with (1–100 nmol/L) or without (control) fibronectin fragment in the presence of 10% fetal bovine serum. In these cultures, deoxyribonucleic acid and proteoglycan contents, as well as the rate of proteoglycan synthesis were determined. Proteoglycan degradation was measured in cultures with or without 10 nmol/L fibronectin fragment. Results. In articular chondrocytes, fibronectin fragment strongly suppressed proteoglycan synthesis and stimulated proteoglycan degradation; the total proteoglycan content was diminished in a dose-dependent manner. Compared to articular chondrocytes, nucleus pulposus cells responded to fibronectin fragments in a similar, although less pronounced manner. On the other hand, anulus fibrosus cells treated with fibronectin fragment did not show any significant effects on proteoglycan degradation. A slight but statistically significant up-regulation of proteoglycan synthesis was observed at 10 nmol/L fibronectin fragment in outer anulus fibrosus cells. However, total proteoglycan content was decreased significantly at high concentrations of fibronectin fragment. Conclusions. Fibronectin fragment has different effects on cell proliferation, proteoglycan synthesis, degradation, and accumulation by articular chondrocytes and intervertebral disc cells. The different effects of fibronectin fragment in those different cell types suggest metabolic differences between these cells, and may further suggest differences in pathways of fibronectin fragment signaling as well as a differential need of these cells to be involved in tissue remodeling in which both anabolic and catabolic pathways might be altered.

The correlation of diffusion-weighted magnetic resonance imaging in cervical compression myelopathy with neurologic and radiologic severity.

Study Design. A retrospective evaluation of diffusion-weighted imaging, apparent diffusion coefficient (ADC) maps, and T2-weighted images in patients with cervical compression myelopathy. Objective. To correlate high signal intensity on ADC maps and T2-weighted images to neurologic severity and radiologic spinal cord compression. Summary of Background Data. Previous studies indicated that the ADC map was more sensitive in detection of cervical compressive myelopathy than T2-weighted imaging. The relationship to neurologic severity has not been previously published. Methods. In 100 patients with or without cervical compressive myelopathy, the magnetic resonance appearance of the spinal cord on ADC maps and T2-weighted images was evaluated independently by 2 readers. On the basis of the presence or absence of abnormality, patients were categorized into 4 groups by type of intramedullary change. The degree of canal compression and the Japanese Orthopedic Association (JOA) score for cervical myelopathy were compared among the 4 types. Results. The type I group consisted of 32 patients without signal change on either ADC maps or T2-weighted images. The type II group had 33 patients with high signal intensity only on the ADC map. The type III group contained 28 patients with high signal intensity on both the ADC map and the T2-weighted images. The type IV group comprised 7 patients with high signal intensity only on T2-weighted images. The degree of canal compression and the JOA scores were significantly different among the 4 groups (P < 0.005). Most type III (25 of 28) and type IV (7 of 7) patients had severe cord compression. Average JOA scores in each type were (I) 16.0, (II) 14.7, (III) 11.7, and (IV) 8.7. Conclusion. ADC maps demonstrated internal changes in the early stages of chronic spinal cord compression, but had limitations for the detection of intramedullary changes in late-stage myelopathy.

Effectiveness of a Lumbar Support Continuous Passive Motion Device in the Prevention of Low Back Pain During Prolonged Sitting

Study Design. Subjective ratings of discomfort were compared between a fixed lumbar support and lumbar support continuous passive motion (CPM) device. Objective. To compare a fixed lumbar support with a lumbar support CPM device during prolonged sitting. Summary of Background Data. To prevent low back pain during prolonged sitting, an inflatable lumbar support CPM has been developed. There are no studies that compare static lumbar support with lumbar CPM using the same pressure in the cushions. Methods. A total of 31 male volunteers without low back pain sat in the same chair for a 2-hour period on each of 3 consecutive days under 3 randomized test methods: 1, no lumbar support; 2, static lumbar support; and 3, lumbar support CPM. Each subject rated low back pain, stiffness, fatigue, and buttock numbness on a visual analog scale (VAS). Fixed lumbar support and CPM device were compared with a same inflation pressure in the cushion. For 10 subjects, the whole body posture and the pressure distribution changes of the human-seat interface during CPM were evaluated. Results. Compared with no lumbar support, a significant improvement in VAS scores for low back pain, stiffness, and fatigue was obtained with both static lumbar support and with lumbar support CPM (P < 0.005). A significant (P < 0.005) improvement for buttock numbness was obtained only with lumbar support CPM. There were no statistical differences in all VAS scores between the fixed lumbar support and the CPM device. A forward rotation of the pelvic region was obtained during inflation of the cushion during CPM. Significant differences (P < 0.05) were found between cushion inflation and deflation periods both in contact areas and in the peak pressures at the human-seat interface. Conclusion. There were no statistical differences in the subjective ratings of discomfort between the fixed lumbar support and the CPM device.

Does the Fists-on-Clavicles Position Represent a Functional Standing Position?

Study Design. Prospective analysis of sagittal vertical axis (SVA) on lateral spine radiographs using 3 different arm positions. Objective. To examine whether fists-on-clavicles position represents a functional standing position. Summary of Background Data. Radiographic visualization of spinal and pelvic sagittal morphology is difficult during relaxed standing because of interference from the arms; however, standing with arms forward-flexed results in a negative shift in SVA. The fists-on-clavicles position was proposed to provide a more functional sagittal profile and adequate visualization of the spine. No existing study compares the SVA between the fists-on-clavicle and relaxed standing positions. Methods. The SVA was measured on standing lateral radiographs of 14 healthy subjects using 3 different arm positions: relaxed with arms-at-side, arms forward-flexed to 45° (shoulder flexion [SF]), and fists-on-clavicles. Results. The mean SVA with relaxed standing was 1.4 ± 1.9 cm. SF produced a significant SVA negative shift (−3.7 ± 2.3 cm, P < 0.001). The fists-on-clavicle position resulted in a reduced but significant SVA negative shift (−2.3 ± 2.1 cm, P < 0.001) compared with relaxed standing. Conclusion. Although the fists-on-clavicles position was better than SF in reducing the SVA negative shift, a significant negative shift did occur in the fists-on-clavicle position compared with relaxed standing.

Anatomical study of superior cluneal nerve entrapment.

OBJECT Entrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel in the space surrounded by the iliac crest and the thoracolumbar fascia is a cause of low-back pain (LBP). Several anatomical and surgical reports describe SCN entrapment as a cause of LBP, and a recent clinical study reported that patients with suspected SCN disorder constitute approximately 10% of the patients suffering from LBP and/or leg symptoms. However, a detailed anatomical study of SCN entrapment is rare. The purpose of this study was to investigate the courses of SCN branches and to ascertain the frequency of SCN entrapment. METHODS Branches of the SCN were dissected in 109 usable specimens (54 on the right side and 55 on the left side) obtained in 59 formalin-preserved cadavers (average age at death 84.8 years old). All branches were exposed at the points where they perforated the thoracolumbar fascia. The presence or absence of an osteofibrous tunnel was ascertained and, if present, the entrapment of the branches in the tunnel was determined. RESULTS Of 109 specimens, 61 (56%) had at least 1 branch running through an osteofibrous tunnel. Forty-two medial (39%), 30 intermediate (28%), and 14 lateral (13%) SCN branches passed through such a tunnel. Of these, only 2 medial branches had obvious entrapment in an osteofibrous tunnel. There were several patterns for the SCN course through the tunnel: medial branch only (n = 25), intermediate branch only (n = 11), lateral branch only (n = 4), medial and intermediate branches (n = 11), medial and lateral branches (n = 2), intermediate and lateral branches (n = 4), and all branches (n = 4). CONCLUSIONS Several anatomical variations of the running patterns of SCN branches were detected. Entrapment was seen only in the medial branches. Although obvious entrapment of the SCN is rare, it may cause LBP.

Changes in physical function after palliative surgery for metastatic spinal tumor: association of the revised Tokuhashi score with neurologic recovery.

Study Design. A retrospective study of patients undergoing palliative surgery for metastatic spinal tumors. Objective. To investigate short-term functional recovery and duration of improvement after palliative surgery, to correlate these outcomes with the revised Tokuhashi score, and to examine the relationship between function and neurologic deterioration. Summary of Background Data. The revised Tokuhashi score is a scoring system used to predict life expectancy for patients with metastatic spinal tumors. The relationship between the revised Tokuhashi score and physical functional improvement after palliative surgery has not been examined previously. Methods. The clinical charts of 86 patients were reviewed. The Eastern Cooperative Oncology Group Performance Status (ECOG-PS) was used to assess physical function. Each score was documented before surgery and at every month after surgery. The duration of ECOG-PS improvement, defined as the period between surgery and deterioration to the preoperative ECOG-PS grade, was correlated with the revised Tokuhashi score. Results. The ECOG-PS grade improved in 44 (51.1%) patients at 1 month postoperative. When ECOG-PS improvement was found after surgery, it persisted above the preoperative level for an average of 9.3 months. At 1 month postoperative, patients scoring 0 to 8 on the total revised Tokuhashi score had significantly lower ECOG-PS improvement (26 of 55 patients) when compared to patients with higher scores (18 of 27 patients, P < 0.05). In 44 patients with ECOG-PS improvement, the existence of major internal organ metastases significantly shortened the duration of improvement (P < 0.05). Conclusion. Palliative surgery benefited half of the patients with metastatic spinal tumor, with a greater probability of benefit found in persons with a higher total revised Tokuhashi score (score 9–15) and/or primary cancers with longer survival times.