Yasuhisa Maezawa

Lordotic alignment and posterior migration of the spinal cord following en bloc open-door laminoplasty for cervical myelopathy: A magnetic resonance imaging study

We investigated lordotic alignment and posterior migration of the spinal cord following en bloc open-door laminoplasty for cervical myelopathy. Fifty-five patients (32 men and 23 women) were studied, with an average follow-up of 2.4 years. Radiological examination included evaluation of lordosis of the cervical spine and spinal cord, degree of enlargement of bony spinal canal, and the magnitude of posterior cord migration. We also correlated these changes with neurological improvement. Postoperatively, there was an average of 5% loss of cervical spine lordosis (P > 0.01) on radiographs and 12% reduction in the lordotic alignment of the spinal cord (P > 0.05) on magnetic resonance imaging. Postoperatively, the size of the bony spinal canal increased by 48%. Posterior cord migration showed a significant correlation with the preoperative cervical spine and spinal cord lordosis (P < 0.05). Thirty-seven (67%) patients with neurological improvement exceeding 50% showed significant posterior cord migration following laminoplasty compared with those demonstrating less than 50% improvement (P = 0.01). Our results suggest that a significant neurological improvement is associated with posterior cord migration after cervical laminoplasty.

Osteoporotic vertebral collapse with late neurological complications

This paper describes 27 patients who had a spinal fracture and underwent an anterior or a posterior spinal decompression, with or without spinal instrumentation, for late neurological compromise secondary to post-traumatic vertebral collapse associated with osteoporosis. Five males and 22 females were studied, with an average follow-up of 3.7 years. The patients developed delayed neurological compromise due to osteoporotic vertebral collapse 1 month to 1.5 years following insignificant spinal fractures. Abnormal hypermobility at the collapsed spinal level with gradual retropulsion of fracture fragments into the spinal canal appeared to contribute to late paralysis. This pathology is treated surgically either anteriorly or posteriorly, but we recommend transpedicular posterolateral decompression and stabilization with a screw-rod construct because of technical ease and minimum invasion.

Herniation of cervical intervertebral disc: immunohistochemical examination and measurement of nitric oxide production.

Study Design. Surgically obtained cervical herniated intervertebral discs were examined histologically and immunohistochemically. The production of nitric oxide (NO) in the local tissue was examined using the electron spin resonance (ESR) method. Objectives. To investigate the local histologic and immunohistochemical changes in cervical disc herniation, including NO production, and to compare such changes with those in autopsy cases. Summary of Background Data. Very little is known about the histopathologic processes of cervical disc herniation. In addition, no information is available on the level of in vivo NO production in cervical disc herniation. Methods. Thirty-six herniated cervical discs obtained from 31 patients were immunohistochemically examined for localization of blood vessels, matrix metalloproteinase (MMP)-3, and inducible NO synthetase (iNOS). We also compared the production of NO, measured by the ESR method, in eight specimens with that of five control discs obtained from fresh cadavers. Results. The presence of herniated discs correlated with the degeneration of cartilaginous endplate and torn anulus fibrosus. Formation of new blood vessels around the herniated discs was detected, using von Willebrand factor antibody, in seven uncontained hernias and 20 contained hernias. Immunohistochemical studies showed the presence of cells positive for MMP-3 (chondrocytes), iNOS (chondrocytes and granulation tissue) in cervical disc hernias. ESR analysis showed a significantly higher NO production in herniated cervical discs than in disc samples of fresh cadavers. Conclusions. Herniated cervical intervertebral disc is characterized by the presence of an inflammatory process associated with neovascularization and increased expression of MMP-3. Production of NO was markedly high in both contained- and uncontained-type hernias.

Calcium crystal deposition in the ligamentum flavum of the cervical spine.

This article reports eight patients who underwent posterior decompressive surgery for myeloradiculopathy caused by calcium crystal deposition in the ligamentum flavum of the cervical spine. All were women with an average age of 72 years and showed neurologic improvement postoperatively. Four patients had diabetes mellitus, and knee meniscus calcification on radiographs were noted in four patients. The ligamentum flavum of C5-6 and C6-7 were sites frequently involved. Crystallographic examination confirmed resected deposits as calcium pyrophosphate dihydrate crystal in all patients and additional hydroxyapatite crystal in two. Histology confirmed marked degeneration in elastic fibers about the calcium deposits. This pathologic condition is possibly spinal manifestation of systemic calcium crystal deposition disease.

Histological investigation of spinal cord lesions in the spinal hyperostotic mouse (twy/twy): morphological changes in anterior horn cells and immunoreactivity to neurotropic factors.

Abstract We examined the morphology of spinal accessory motoneurons and immunoreactivity to neurotrophins, brain-derived neurotropic factor (BDNF) and neurotrophin (NT)-3, as well as the presence of reactive astrocytosis in 70 tiptoe walking Yoshimura (twy) mice that develop calcification at C1-C2 vertebral level compressing the spinal cord. At the level of compression, the area of neuronal soma and total length of dendrites of wheat germ agglutinin-horseradish peroxidase (WGA-HRP)-labelled accessory motoneurons in the medial cell pool decreased significantly with decrement in motoneuron population, relative to the control. In contrast, at sites rostral to the compressive lesion, a significant enlargement of the neuron soma and dendritic elongation were noted, associated with increased motoneuron population and decreased transverse area of the cord at the level of compression. At this site, enhanced BDNF and NT-3 immunoreactivities were evident in the anterior horn cells. In mice with a more severe degree of compression, astrocyte-like cells showing BDNF immunoreactivity became abundant and axons in the anterior column demonstrated a marked NT-3 immunoreactivity. Our results suggest increased functional activity of anterior horn cells at levels rostral to the site of compression. We speculate that the presence of BDNF and NT-3 in neurons and astrocyte-like cells is proportionate to the severity of chronic mechanical compression and may contribute to the heterotropic neuronal reserve and survival.

Quantitative analysis of the spinal cord motoneuron under chronic compression: an experimental observation in the mouse.

We investigated quantitative changes in spinal cord motoneurons following chronic compression using a mouse model of cervical cord compression. Twenty-five tiptoe-walking Yoshimura (twy) mice with calcified mass lesions compressing the spinal cord posterolaterally at the C1–C2 vertebral levels were compared with five Institute of Cancer Research (ICR) mice that served as controls. Spinal cord motoneurons in the anterior grey horn between the C1 and C3 spinal cord segments were Nissl-stained and counted topographically and then analysed in relation to the extent of spinal cord compression. The number of motoneurons in C1–C3 spinal cord segments decreased significantly with a linear correlation with the transverse area of the spinal cord when the cord was compressed to 50–70% of control values. A significant reduction in the number of motoneurons occurred at the C2–C3 spinal cord segment compressed at the C1–C2 vertebral level. In contrast, at the level rostral to the C1 vertebra, the number of motoneurons increased significantly in proportion to the magnitude of compression. The current study demonstrates that a number of neurons, morphologically consistent with anterior horn cells, were observed at a rostral site absolutely free of external compression where no such cells normally exist.

Ganglion cyst of the posterior longitudinal ligament causing lumbar radiculopathy: case report

We describe a man aged 26 years who presented with a neurological syndrome, which was found on lumbar radioculopathy to be due to a ganglion cyst originating from the posterior longitudinal ligament. Based on MRI findings, a cystic lesion was suspected, a round lesion at L4 level with no connection to the adjacent facet or to the dura matter. During surgery, a liquid-containing cystic lesion was found to originate from the posterior longitudinal ligament at L4 level. The resected cyst was diagnosed histologically as a ganglion cyst. A complete cure was established after surgery and no recurrence was noted at a follow-up 1.7 years postoperatively. A ganglion cyst of the posterior longitudinal ligament should be considered in the differential diagnosis of a cyst in the lumbar region causing neurological complications.

Progressive changes in neurofilament proteins and growth-associated protein-43 immunoreactivities at the site of cervical spinal cord compression in spinal hyperostotic mice.

Study Design. Immunohistochemical examination of the expression and localization of neurofilament (NF) proteins and growth-associated protein (GAP)-43 in spinal hyperostotic (twy/twy) mice with progressive compression of the cervical spinal cord. Objective. To determine the biologic functions of NF proteins and GAP-43 in the mouse cervical spinal cord during chronic mechanical compression. Summary of Background Data. The pathologic and repair process in the chronically compressed spinal cord are understood poorly. The present authors hypothesized that there existed an increased expression of NF proteins and GAP-43 in twy/twy mice during the lengthy period of spinal cord compression, which resembles compressive myelopathy. Methods. The cervical spinal cords of 54 twy mice (aged 8 weeks [n = 18], 14 weeks [n = 18], and 20 weeks [n = 18]) and 18 control animals were examined histologically. Using appropriate antibodies, sections were also stained immunohistochemically for NF proteins and GAP-43. Results. Separation of the myelin sheath from the axon and axonal swelling with deformation were detected in the anterior and lateral funiculi of the spinalcords of 20-week-old twy/twy mice. No such changes were noted in 8-week-old twy mice. In twy/twy mice aged 8 and 14 weeks with mild-to-moderate compression, weak immunoreactivities (mainly in the white matter) for NF proteins and GAP-43 were noted; however, in 20-week-old twy/twy mice, these axons stained strongly positive and immunoreactive swollen axons were present. The relative area of GAP-43 immunoreactive axons gradually increased between 8 and 20 weeks in each column, particularly in the anterior and lateral funiculi in the contralateral side of compression. Conclusions. The results showed that the expression of NF proteins and GAP-43 in the white matter increased proportionally with the magnitude of spinal cord compression, and indicated the possible involvement of GAP-43 in both axonal degeneration and repair processes in the chronically compressed spinal cord.

Microsurgical nerve root canal widening without fusion for lumbosacral intervertebral foraminal stenosis: technical notes and early results

We describe a technique for microsurgical widening of the nerve root canal in the lumbosacral spine. We also report our early results in 31 patients (19 men and 12 women; average follow-up, 3.2 years) with such foraminal stenosis but without osseous defects in the pars interarticularis and/or spondylolisthesis. The affected nerve root was decompressed by interlaminar medial foraminotomy followed by lateral laminotomy and foraminotomy using a microsurgical technique. The procedure aimed at preserving bony continuity of the pars interarticularis and segmental motion. Neurological results showed a favourable improvement of radicular symptoms and of intermittent claudication. The need for segmental fusion at the operated segment was excluded in 30 patients, but one patient subsequently required a transpedicular screw procedure with bone grafting. We recommend the present technique for effective decompression of the nerve root within the neural foramen, simultaneously maintaining lumbar spine mobile function.

Three-dimensional topographic analysis of spinal accessory motoneurons under chronic mechanical compression: an experimental study in the mouse.

We investigated the effect of chronic mechanical compression of the cervical spinal cord on the number of spinal accessory motoneurons in 25 tiptoe-walking Yoshimura mice. The animals had calcified deposits in the atlantoaxial membrane at the C1-C2 vertebral level, compressing the spinal cord posterolaterally. Motoneurons of the spinal accessory nerve between C1 and C5 segments were labelled using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injected into the sternocleidomastoid muscles. The counted cells were processed into a three-dimensional computer display to analyse the cytoarchitectonic changes caused by external cord compression. The number of WGA-HRP-labelled spinal accessory motoneurons was significantly reduced on the affected side. The number of motoneurons in compromised C2 and C3 cord segments correlated linearly with the extent of mechanical compression, but no such relationship was present on the contralateral side. There was an increase in the number of WGA-HRP-labelled spinal accessory motoneurons in the medial cell pools of the anterior grey horn at a level most rostral to the compression, and in the ventrolateral cell pools at levels immediately rostral to the compression. Our findings suggest that the spinal accessory motoneurons translocate rostral to the area of external compression in order to avoid mechanical injury.