Sueo Nakama

Early exercise in spinal cord injured rats induces allodynia through TrkB signaling

Rehabilitation is important for the functional recovery of patients with spinal cord injury. However, neurological events associated with rehabilitation remain unclear. Herein, we investigated neuronal regeneration and exercise following spinal cord injury, and found that assisted stepping exercise of spinal cord injured rats in the inflammatory phase causes allodynia. Sprague-Dawley rats with thoracic spinal cord contusion injury were subjected to assisted stepping exercise 7 days following injury. Exercise promoted microscopic recovery of corticospinal tract neurons, but the paw withdrawal threshold decreased and C-fibers had aberrantly sprouted, suggesting a potential cause of the allodynia. Tropomyosin-related kinase B (TrkB) receptor for brain-derived neurotrophic factor (BDNF) was expressed on aberrantly sprouted C-fibers. Blocking of BDNF-TrkB signaling markedly suppressed aberrant sprouting and decreased the paw withdrawal threshold. Thus, early rehabilitation for spinal cord injury may cause allodynia with aberrant sprouting of C-fibers through BDNF-TrkB signaling.

Regional difference in the appearance of apoptotic cell death in the ligamentum flavum of the human cervical spine.

Ossification or calcification of the ligamentum flavum (LF) is relatively common in the middle and lower cervical, thoracic, and lumbar spine but extremely rare in the upper cervical region. This clinical fact suggests that there exist local factors promoting or preventing ossification or calcification of LF. However, little is known about the differences in the ultrastructure and cellular alterations of the LF between the different spinal levels, even in the cervical spine. With electron microscopy, we examined samples of LF collected surgically from the upper and lower cervical spine regions; we then studied the apoptotic appearance of ligament cells using a preferential labeling method. We found direct evidence of apoptosis of ligament cells in the LF. Apoptosis was more apparent in the upper region samples than in the lower region samples. The spaces around the normal fibroblasts were filled with thick collagen fibrils, but the collagen fibrils disappeared around the apoptotic bodies and thin fibrils were formed. The difference of the level of apoptosis may correlate to the ultrastructual difference of LF, and our data will benefit further investigations seeking to clarify the mechanism of various pathological conditions in the human LF.

An ultrastructural study on the ligamentum flavum of the cervical spine in patients with ossification of the posterior longitudinal ligament

Some histological analyses of the ossification of the posterior longitudinal ligament (OPLL) have been reported, but no ultrastructural studies of the ligamentum flavum (LF) in patients with OPLL have been published to date. To understand the pathology of the ossification of the spinal ligament, we examined, by electron microscopy, ultrastructural changes in the LF in cases of OPLL and made a comparison with the LF in cervical spondylotic myelopathy (CSM). Subjects were three men and two women with cervical OPLL who underwent longitudinal spinous process-splitting laminoplasty. During surgery, a small piece of the LF was collected from C2–C3 to C7–T1 and was then analyzed by light and electron microscopy. We observed atrophic elastic bundles with a two-layer structure and disarrangement, a partially torn area, the disappearance of microfibrils, and an enlarged interstitium with an irregular alignment of collagen fibrils. We observed some properties of a cell preceding its death: the initial phase may be the disappearance of the plasma-membrane, followed by the scattering of many organellae around its degenerated nucleus. Finally, many extracellular plasma membrane-invested particles that resemble matrix vesicles remain there without phagocytosis. These results suggest that ultrastructural abnormalities exist in the spinal ligament in cases of ossification of the spinal ligament.

Scanning and transmission electron microscopic observation of femoral head feeding vessels in stroke-prone spontaneously hypertensive rats

Stroke-prone spontaneously hypertensive rats (SHRSP) are known to show necrosis of the femoral head with a frequency of about 50%. This rat has thus been used as an animal model for necrosis of the femoral head in many studies. In a detailed investigation of feeding vessel disorders that cause femoral head necrosis, we observed changes over time in the feeding vessels using scanning electron microscopy and transmission electron microscopy. In scanning electron microscopy of vascular casts, abnormal findings in feeding vessels of SHRSP with aging from the immature stage included contortion and bending in the lumen with overall narrowing. Under transmission electron microscopy, decreased numbers of smooth muscle cells and increased amounts of collagen fibers were marked, and these changes with hypertrophy of vascular walls might be similar to those of arteriolosclerosis. The structural changes first revealed by transmission electron microscopic observation might cause the friability of the feeding vessels so that contortion and bending occurred, suggesting transient obstruction of blood flow to the femoral head and subsequent induction of femoral head necrosis. These findings should help in understanding the causes of femoral head necrosis in humans, including Perthes’ disease.

Pathologic Fractures Extended to the Metacarpal Head Related with Enchondromas at the Metacarpal Neck

We present two cases of pathologic fractures extended to the metacarpal head related with enchondromas at the metacarpal neck treated by surgery. The timing of surgery varied between the two cases. The first was operated without delay, using tumor curettage and β-TCP (tricalcium phosphate) packing in the cavity, followed by internal fixation of the fracture using a screw and Kirshner wires. In the second case, tumor curettage and β-TCP packing was performed after fracture union. Favorable clinical outcomes were obtained for both cases.

Synovial Osteochondromatosis at the Carpometacarpal Joint of the Thumb

Synovial osteochondromatosis (SOC) is a benign tumor characterized by synovial connective tissue metaplasia. SOC commonly affects major joints including the knee followed by the hip, elbow, and wrist. SOC cases in the hand are not reported as often as SOC of major joints. Particularly SOC of the carpometacarpal joint of the thumb is rare. We report on a 57-year-old female with primary SOC of the carpometacarpal joint of her left thumb. Surgical excision was performed and the patient had no symptoms with full range of motion of her left thumb. At 3 years of follow-up, there was no recurrence.

Ultrastructural change of ligamentum flavum in galactosialidosis

AbstractPurpose Galactosialidosis is an autosomal recessive lysosomal storage disease caused by deficiency of both α-neuraminidase and β-galactosidase due to a defect of the protective protein/cathepsin A. Three clinical subtypes have been described, depending on the age of onset and severity of the symptoms: the early infantile, late infantile and juvenile/adult form. We report an adult-type patient who underwent surgery for galactosialidosis-related spinal deformity, and showed a favorable course thereafter.MethodsThe patient was a 50-year-old male, and he consulted our hospital with pain of the bilateral anterior thigh. Lumbar radiograph showed applanation and horn-like deformity of the L2 vertebral body, which is characteristic of this disease, narrowing of the L1/2 intervertebral space, and topical kyphosis. Fenestration between the L1/2, decompression of the L2 nerve root, and posterolateral fusion involving the T12 to L3 were performed.ResultsImmediately after surgery, pain of the lower limbs disappeared. During the 2-year postoperative follow-up, bone assimilation was achieved, showing a favorable course. Histological examination of the ligamentum flavum (LF) collected during surgery showed that the elastic fibers were thin, whereas the collagen fibers were abundant and dense. The ligament cells were swollen, and there were a large number of vacuoles in the cytoplasm.ConclusionThis is the first report on spinal surgery for adult-type galactosialidosis and histological examination of spinal LF.