Toshimi Aizawa

Spinal dumbbell tumors: an analysis of a series of 118 cases

OBJECT The authors analyzed a series of 118 cases of spinal dumbbell tumors to elucidate the feature of the tumors. METHODS Of 674 cases of spinal cord tumors, the incidence of dumbbell tumors was studied. The tumors were analyzed, and the authors focus on the distribution of age and sex, the pathological diagnoses, their locations, Eden classification, and the surgical methods used. RESULTS The incidence of dumbbell tumors was 18%. The mean patient age was 43 years, which was younger than that for all spinal cord tumors (mean 50 years). There were 11 patients younger than 10 years of age. The rate of dumbbell tumors in the cervical spine was significantly higher than that of all spinal cord tumors. Fifteen (18%) of the 81 schwannomas were observed in the C-2 nerve root, thus having a higher incidence than those in the other nerve roots. In 99 cases (84%), the tumors were removed through a hemilaminectomy with or without a facetectomy and posterior fusion. Of 118 cases, 69% of the tumors were schwannomas, and malignant tumors were found in 10 cases (8.5%). Seven (64%) of 11 patients younger than 10 years of age had malignant tumors. Three patients older than 10 years of age had malignant tumors, thus accounting for 2.8% of the 107 older patients. CONCLUSIONS The incidence of dumbbell tumors was 18%, and they are not uncommon. Malignant dumbbell tumors were more common in children younger than 10 years of age than in older patients.

APOPTOSIS AND PROLIFERATION OF GROWTH PLATE CHONDROCYTES IN RABBITS

The growth plates of the femoral head of Japanese white rabbits aged 5, 10, 15 and 20 weeks were stained for apoptotic and proliferating chondrocytes using the TUNEL and PCNA antibody staining techniques. Both TUNEL- and PCNA-positive chondrocytes were detected in all of the specimens. The positive ratios of both stainings were calculated for the whole plate and for the resting, proliferating and hypertrophic zones. The highest ratios in both stainings occurred in the hypertrophic zone in all age groups. With growth, the TUNEL-positive ratio increased whereas the proliferating ratio decreased. We suggest that the increase in chondrocytic death by apoptosis and the decrease in cell proliferation potential led to closure of the growth plate.

Myofibers Express IL-6 After Eccentric Exercise

Background Interleukin (IL)-6 is locally produced in skeletal muscles and shows a remarkable increase in plasma after eccentric exercises. Objective To elucidate the cell types in the muscles responsible for IL-6 production after eccentric exercises. Study Design Controlled laboratory study. Methods An eccentric contraction model was made using electrical stimulation. The authors investigated the muscle damage and regeneration processes after eccentric exercises histologically, and the cell types expressing IL-6 and its subcellular compartimentalization with time immunohistochemically after eccentric exercises. Results Swollen myofibers were detected from 8 hours to 3 days after exercises. Disrupted myofibers were detected from 24 hours to 7 days, with a peak of 3 days. IL-6 was detected only in the cytoplasm of myofibers until 12 hours; thereafter, it was found in the inflammatory cells and proliferating satellite cells as well. The swollen myofibers were negatively stained for IL-6. The positive ratios of IL-6 in myofibers immediately increased after exercises, peaked in 12 hours, and then decreased. Conclusions After eccentric exercises, IL-6 expression increased in myofibers preceding the disruption of myofibers. IL-6 might be closely related to muscle damage caused by strenuous exercises.

Results of surgical treatment for thoracic myelopathy: minimum 2-year follow-up study in 132 patients

OBJECT Thoracic myelopathy is uncommon compared with cervical myelopathy. In this study, data obtained in patients with thoracic myelopathy caused by degenerative processes of the spine were retrospectively analyzed to clarify the surgical outcomes and to examine the various factors affecting the postoperative improvement. METHODS Between 1988 and 2002, 132 patients with thoracic myelopathy underwent surgery and a minimum 2-year observation period. Clinical data were collected from medical and operative records, and sagittal alignment of the spine was measured on radiographs. The patients were evaluated pre- and postoperatively using the modified Japanese Orthopaedic Association (JOA) scale (maximum score 11). The relationships among various factors affecting the preoperative severity of myelopathy and postoperative improvement were also examined. RESULTS The population consisted of 97 men (mean age at surgery was 58 years) and 35 women (mean age at surgery 62 years). Myelopathy was caused by ossification of the ligamentum flavum (OLF) in 73 patients, ossification of the posterior longitudinal ligament (OPLL) in 21, combined OLF-OPLL in 10, intervertebral disc herniation (IDH) in 15, posterior bone spur in 11, and OLF with IDH or posterior bone spur in one patient each. The surgical outcome was relatively good: a mean preoperative JOA score of 5.3 improved to a mean score of 7.8 at the last follow-up, 50 months on average after surgery. Thoracic myelopathy caused by OPLL, however, was associated with lower postoperative scores and recovery rates. In more than half of the patients the authors documented an increase of kyphosis of less than 2 degrees. CONCLUSIONS Patients with a shorter preoperative duration of symptoms and milder myelopathy experienced significantly better postoperative neurological conditions, which indicated that those who present earlier with fewer disabilities should be recommended to undergo surgery in time, although the surgical treatment for OPLL still involves many problems.

Crowned Dens Syndrome

BACKGROUND Patients with crowned dens syndrome typically present with severe neck pain and have calcium deposits around the odontoid process of the axis on radiographs. To our knowledge, the cases of only thirty-five patients have been reported in the English-language literature and the clinical features remain unclear. The purposes of this study were to examine the clinical features of crowned dens syndrome, determine treatment outcomes, and propose diagnostic criteria. METHODS Forty patients with severe neck pain had calcium deposition around the odontoid process on computed tomography scans, and they were thus diagnosed as having crowned dens syndrome. Data were collected in relation to these patients, including the date of onset of neck pain, the presence of inflammatory indicators (increased body temperature, C-reactive protein levels, and white blood-cell count), and treatment outcomes. RESULTS The male-to-female ratio was 0.6, and two-thirds of the patients were more than seventy years of age. All patients had markedly restricted neck motion, particularly in rotation, and all had one or more positive inflammatory indicators. Calcium deposition was detected in all areas around the odontoid process, but chiefly behind the process. Pain was typically relieved by nonsteroidal anti-inflammatory drugs, prednisolone, or both. A combination of both appeared to be the most effective. CONCLUSIONS We believe that crowned dens syndrome is more common than previously recognized, especially in elderly patients. It is diagnosed on the basis of acute and severe neck pain; marked restriction of neck motion, particularly in rotation; the presence of inflammatory indicators, such as an elevated C-reactive protein level; calcium deposition around the odontoid process detected by computed tomography; no history of trauma; and the exclusion of other inflammatory diseases and tumors. Prednisolone and nonsteroidal anti-inflammatory drugs in combination are the recommended treatment for symptom relief.

Histologic Findings and Possible Causes of Osteochondritis Dissecans of the Knee

Background The histologic findings of osteochondritis dissecans of the knee vary widely, leading to differences in the interpretation of its origins. Hypothesis The differences in the histologic findings of osteochondritis dissecans might represent a course of pathologic progression. Study Design Descriptive laboratory study. Methods Twelve knees in 11 patients (average age, 16 years) with osteochondritis dissecans of the medial femoral condyle were treated by biological internal fixation. During the surgery, cylinder osteochondral plugs were taken from the center of the osteochondritis dissecans lesion and examined with light microscopy. Results A complete or partial cleft separated the specimens into 2 parts: basal and fragment sides. The surface of the basal side was covered with dense fibrous or cartilaginous tissue and active bone remodeling was found beneath the surface. In the fragment side, the deep surface was also covered with dense fibrous or cartilaginous tissue and the articular surface consisted of normal articular cartilage. The area between these 2 surfaces could be classified into 3 types: (1) necrotic subchondral trabeculae, (2) viable subchondral trabeculae, and (3) cartilage without bone trabeculae. Conclusion Based on the histologic findings of this study, the following origins and the pathologic progression of osteochondritis dissecans might be assumed: the initial change in the subchondral area is bone necrosis or subchondral fracture; the necrotic bone is then absorbed and replaced either by viable subchondral trabeculae or cartilage without bone trabeculae. Clinical Relevance The results of this histologic study provide readers with several insights about the causes and treatment options of osteochondritis dissecans.

Idiopathic herniation of the thoracic spinal cord: report of three cases.

Study Design. Cases are reported and the literature is reviewed. Objective. To present three cases involving idiopathic herniation of the thoracic cord. Summary of Background Data. Idiopathic spinal cord herniation is a very rare condition. Only 20 cases have been reported. The radiographic and intraoperative findings concerning this herniation remain insufficient, and its pathophysiology is less understood. Methods. Idiopathic herniation of the thoracic spine was managed operatively in the three cases. The clinical, radiologic, and intraoperative features in these cases are described, and the pathophysiology of this disorder is discussed from a review of the literature. Results. Two of the three patients had a defect in the inner layer of the duplicated ventral dura mater through which the spinal cord was herniated. The third patient had a ventral epidural cyst into which the spinal cord had protruded. Operative reduction of the spinal cord improved motor power in all three patients, although sensory disturbance remained unchanged. Conclusions. There should be several types of idiopathic spinal cord herniation. This is the first report of this herniation that focuses the abnormalities of the ventral dura mater, together with image and intraoperative findings.

Dynamic Change of Dural Sac Cross-Sectional Area in Axial Loaded Magnetic Resonance Imaging Correlates With the Severity of Clinical Symptoms in Patients With Lumbar Spinal Canal Stenosis

Study Design. Cross-sectional registry and imaging cohort study. Objective. To examine whether the dural sac cross-sectional area (DCSA) in axial loaded magnetic resonance imaging (MRI) correlates with the severity of clinical symptoms in patients with lumbar spinal canal stenosis (LSCS). Summary of Background Data. Many studies have analyzed the relationship between DCSA on conventional MRI and the severity of symptoms in LSCS, but the link is still uncertain. Recently, axial loaded MRI, which can stimulate the spinal canal of patients in the upright position, has been developed. Axial loaded MRI demonstrates significant reduction of DCSA and provides valuable radiologic findings in the assessment of LSCS. However, there has been no study of the correlation between DCSA in axial loaded MRI and the severity of symptoms in LSCS. Methods. In 88 patients with LSCS, DCSA in conventional MRI, axial loaded MRI, and changes in the DCSA were determined at the single most constricted intervertebral level. The severity of symptoms was evaluated on the basis of the duration of symptoms, walking distance, visual analogue scale of leg pain/numbness, and Japanese Orthopaedic Association score. Spearman correlations of the DCSA in conventional MRI, axial loaded MRI, and changes in the DCSA with the severity of symptoms were analyzed. In addition, the severity of symptoms and DCSA in conventional and axial loaded MRI were compared, respectively, between patients with and without significant (>15 mm2) changes in the DCSA. Results. The DCSA in axial loaded MRI had good correlations with walking distance and Japanese Orthopaedic Association score (rs = 0.46 and 0.45, respectively; P < 0.001). In addition, the change in the DCSA significantly correlated to walking distance, visual analogue scale of leg numbness, and Japanese Orthopaedic Association score (rs = 0.59, 0.44, and 0.54, respectively; P < 0.001). Furthermore, the symptoms were significantly worse in patients with more than 15 mm2 change in the DCSA (P < 0.001). Axial loaded MRI, but not conventional MRI, showed a significantly smaller DCSA in patients with more than 15 mm2 change in the DCSA (P < 0.05). Conclusion. DCSA in axial loaded MRI significantly correlated with the severity of symptoms. Axial loaded MRI demonstrated that changes in the DCSA significantly correlated with the severity of symptoms, which conventional MRI could not detect. Thus, MRI with axial loading provides more valuable information than the conventional MRI for assessing patients with LSCS.

Clinical significance of intramedullary Gd-DTPA enhancement in cervical myelopathy

Study design:Prospective multicenter study.Objective:To clarify the significance of intramedullary Gd-DTPA enhancement in cervical myelopathy, the prevalence, morphologic features, clinical relevance and postoperative change were investigated.Setting:Four hospitals in Japan.Methods:A total of 683 patients with cervical myelopathy who underwent decompressive surgery were consecutively examined. T1, 2 and Gd-DTPA-enhanced MRI were taken before surgery. Fifty consecutive cases without intramedullary enhancement were allocated in the non-enhancement group. The following variables were investigated: prevalence of the enhancement, the morphologic feature, the relationship between the enhancement and T2 high-intensity areas, the change of the Japanese Orthopedic Association (JOA) score for cervical myelopathy and the change of the enhancement after surgery.Results:Intramedullary enhancement was observed in 50 cases (7.3%). The enhancements were observed between the most severely compressed disc and the cranial half of the lower vertebral body. On axial images, they were observed at the posterior or posterolateral periphery of the spinal cord. Enhancement areas were observed within T2 high-intensity areas and smaller than them. The preoperative JOA score was 9.8±2.8 points in the enhancement group and 9.8±3.3 points in the non-enhancement group (NS). The postoperative JOA score was 12.7±2.9 points in the enhancement group and 14.2±2.4 in the non-enhancement group (P=0.006). Intramedullary enhancement disappeared in 60% of the patients 1 year after surgery.Conclusion:Intramedullary enhancement indicated not the severity of preoperative symptoms, but a sign of a worse prognosis.

Incidence of complications associated with spinal endoscopic surgery: nationwide survey in 2007 by the Committee on Spinal Endoscopic Surgical Skill Qualification of Japanese Orthopaedic Association

BackgroundThis report was conducted to elucidate the current status of spinal endoscopic surgery and relevant incidents through analysis of the results of a questionnaire survey conducted in 2007 by the Committee on Spinal Endoscopic Surgical Skill Qualification of the Japanese Orthopaedic Association (JOA).MethodsQuestionnaire forms were sent to 2011 training facilities nationwide certified by the JOA, and 1082 of these facilities returned the filled questionnaires (response rate 53.8%). Of these facilities, 257 (23.8% of the responding facilities) undertook spinal endoscopic surgery in 2007. These institutions were asked to fill in the survey form with the details of the operations and relevant incidents as well as the incident levels.ResultsIn total, the 257 facilities performed 6239 spinal endoscopic surgeries during 2007. Posterior spinal endoscopic surgery constituted most of the operations (6217 cases, 98.2%) including 4336 cases of microendoscopic discectomy (MED), 1273 cases of microendoscopic laminectomy or fenestration, and 379 cases of transforaminal or posterior lumbar interbody fusion. The total number of incidents was 133 (2.13%). The numbers of incidents by operative method were 75 (56.4%) during MED, 57 (42.9%) during microendoscopic laminectomy or fenestration, and 1 (0.8%) during interbody fusion. Of 133 incidents, dural tear occurred in 99 (74.4%), injury of the cauda equina or a nerve root in 7 (5.3%), facet fracture in 7 (5.3%), hematoma and wrong level in 6 each (4.5%), and wrong side and bedsore in 1 each (0.8%). The incident level was level 1 in 6, level 2 in 24, level 3a in 82, level 3b in 16, level 4 in 5, and level 5 (fatal) in 0.ConclusionsThe results of this survey revealed an increasing trend of spinal endoscopic surgery and a decreasing trend of the complication rates. The complication rates of spinal endoscopic surgery were not higher than those of conventional surgery, indicating the safety of this surgical method.