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Both the spontaneous shrinkage and the disappearance of disc hernia have been confirmed through the use of computed tomography (CT) and magnetic resonance imaging (MRI). There is, however, no practical method to predict the likely absorption of the herniated mass. The objective of this study was to predict the spontaneous absorption of disc hernia by MRI, and to select the optimum treatment. The study involved 65 patients with lumbar disc hernias. Conservative treatment was carried out in 21 patients, while 44 patients underwent herniotomy. In the nonoperated patients, an MRI was taken both during the painful period, and shortly after pain remission. Hernial shrinkage was evaluated according to the decrease in the calculated volume, in addition to the decrease in hernial area, calculated by MRI. In the operated group, preoperative MRI enhancement, type of hernia, and invasion of granulation tissue in the histological specimens were studied. In the 21 nonoperated patients, the volume (mean±SD) was 0.488±208cm3(range, 0.197–0.931cm3) in the painful period and 0.214±0.181cm3(range, 0.0–0.744cm3) in the remission period. This decrease in volume was statistically significant. There was also a greater decrease in hernias exhibiting positive enhancement by MRI. In the operated patients, hernias that penetrated the posterior longitudinal ligament (PLL) had high rates of preoperative enhancement, and these hernias showed invasion of granulation tissue with marked neovascularization. Positive enhancement by MRI confirms an ongoing absorption process. Enhanced MRI can be a good method for the prediction of spontaneous absorption of lumbar disc hernias.

Abstract.: Both the spontaneous shrinkage and the disappearance of disc hernia have been confirmed through the use of computed tomography (CT) and magnetic resonance imaging (MRI). There is, however, no practical method to predict the likely absorption of the herniated mass. The objective of this study was to predict the spontaneous absorption of disc hernia by MRI, and to select the optimum treatment. The study involved 65 patients with lumbar disc hernias. Conservative treatment was carried out in 21 patients, while 44 patients underwent herniotomy. In the nonoperated patients, an MRI was taken both during the painful period, and shortly after pain remission. Hernial shrinkage was evaluated according to the decrease in the calculated volume, in addition to the decrease in hernial area, calculated by MRI. In the operated group, preoperative MRI enhancement, type of hernia, and invasion of granulation tissue in the histological specimens were studied. In the 21 nonoperated patients, the volume (mean ± SD) was 0.488 ± 208 cm3 (range, 0.197–0.931 cm3) in the painful period and 0.214 ± 0.181 cm3 (range, 0.0–0.744 cm3) in the remission period. This decrease in volume was statistically significant. There was also a greater decrease in hernias exhibiting positive enhancement by MRI. In the operated patients, hernias that penetrated the posterior longitudinal ligament (PLL) had high rates of preoperative enhancement, and these hernias showed invasion of granulation tissue with marked neovascularization. Positive enhancement by MRI confirms an ongoing absorption process. Enhanced MRI can be a good method for the prediction of spontaneous absorption of lumbar disc hernias.

This study was undertaken to determine whether or not nitric oxide metabolites (NO2−plus NO3−: NOx levels) in cerebrospinal fluid (CSF) would be predictors of treatment outcome in patients with degenerative lumbar diseases (DLD) including lumbar disc herniation (LDH) and lumbar spinal canal stenosis (LCS). The NOx levels in CSF were measured using an NO analyzer based on the Griess method. Six healthy volunteers and 18 patients with painless diseases were included in the control group. The pre- and postoperative NOx levels in 25 DLD patients, who underwent herniotomy for LDH (17 patients) or selective decompression for LCS (eight patients), were analyzed. The postoperative follow-up periods were approximately 8 months. Nineteen of 25 DLD patients, whose preoperative NOx levels were two standard deviations higher than the mean NOx levels of an age-matched control group, were included in an NO elevated (NOE) group. Among the 25 DLD patients, the preoperative NOx levels in six patients (young LDH group) were within the normal range. The pain-related Japanese Orthopaedic Association score and the Hirabayashi recovery rate were respectively used to evaluate the pain severity and the degree of pain relief. The preoperative and changes of postoperative NOx levels in the NOE group were negatively correlated with the Hirabayashi recovery rate. Normal postoperative NOx levels and excellent pain relief were achieved in young DLD patients. In conclusion, the preoperative and changes in postoperative NOx levels are quantitative predictors of postoperative pain relief in DLD patients.

To elucidate the involvement of NO in pain transmission in humans, we measured NO metabolites (nitrite/nitrate) in the CSF of patients with painful diseases using an NO analyzer based on the Griess method. The nitrite/nitrate levels in patients with degenerative lumbar disease (DLD), but not those with fracture or appendicitis, were significantly higher than those in an age-matched control group. The duration of pain in the DLD group was much longer than that in the fracture or appendicitis group. The nitrite/nitrate levels in the middle-aged and elderly DLD patients depended on the duration of pain. These data probably suggest that the duration of pain is critical for the elevation in nitrite/nitrate levels.

Background/Aims:Pseudotumors of the craniovertebral junction (PTCVJ) are observed in long-term hemodialysis (HD) patients. There are neither criteria for diagnosis nor guidelines for screening. We attempted to determine magnetic resonance imaging (MRI) findings that could be used to detect PTCVJ, to determine the prevalence of PTCVJ, and to evaluate whether destructive spondyloarthropathy (DSA) might be a yardstick for selection of patients for MRI examination for PTCVJ. Methods:MRI were examined in 19 DSA patients (8 males, 11 females, age 61.4 ± 7.3 years, HD duration 17.0 ± 4.4 years) and in 20 sex-, age-, and HD-duration-matched non-DSA patients (9 males, 11 females, age 57.5 ± 6.6 years, HD duration 17.7 ± 4.9 years). We evaluated MRI characteristics of PTCVJ according those which occur due to rheumatoid arthritis. Results:PTCVJ were characterized as follows: disappearance of fat pads in the upper region (supradental PTCVJ), intensity change of the ‘predental triangle’ in the anterior region (predental PTCVJ), and thickening of cruciform ligaments (retrodental PTCVJ). The prevalence of PTCVJ among patients undergoing HD more than 10 years was high (26 out of 39; 66.7%). The prevalence of PTCVJ was not different between DSA and non-DSA groups. Conclusion:We verified that the above MRI findings might be helpful in the detection of PTCVJ. These findings were observed frequently and independently also in patients with DSA.

Using human cadaver spines, the authors compared the effect of using a combination of pedicle screw and laminar hook on the same vertebra with that of using a pedicle screw alone in reference to bone mineral density of the vertebra under nondestructive cyclic loading.

A study of neovascularization with respect to the anulus and the endplate.

Crosssectional regional bone mineral density of the pedicle was measured by peripheral quantitative computed tomography. Biomechanical tests were performed to clarify the role of the pedicle in screw stability.

The reactions to sequestrated disc fragments, which were removed surgically from 35 patients, were examined histologically.

Introduction of a new diagnostic procedure and a report on its usefulness.

Radiologic and operative findings of intravertebral cleft in the osteoporotic spine were investigated and the pathomechanism discussed.

In this review paper, we will introduce the advantages and laser characteristics of GaInAsP/InP surface-emitting (SE) lasers. In order to obtain the room temperature oscillation of the SE laser diodes, it is very important to reduce not only its threshold current density but also threshold current itself. To decrease its threshold current density and/or its threshold current, we investigated some possible SE laser structures. First, we tried to reduce the threshold current density by introducing (i) a Au/SiO2 mirror, (ii) a dielectric multilayer mirror to increase the n-side (output-side) reflectivity, and (iii) multi-active-layer structure. Next, to reduce the threshold current, certain types of current confining structure, namely (i) a round-high-mesa/polyimide-buried structure, (ii) a planar buried heterostructure (PBH), (iii) a circular buried heterostructure (CBH) with SiO2 mask and (iv) a flat surface circular buried heterostructure (FCBH), were investigated. The threshold current of the SE laser was reduced to 18 mA and its highest operation temperature was raised to 263 K (−10°C).

Abstract: We report a 49-year-old woman with a spinal cord ependymoma located in the thoracolumbar region. At surgery, a soft dark-grayish tumor, which contained a hard whitish area, was removed. The specimen was a moderately cellular tumor with a central core made up of collagen nodules poor in cellular elements. Many of the tumor cells possessed ground glass-like eosinophilic cytoplasm, and frequently foamy tumor cells were evident. Perivascular pseudorosettes, ependymal rosettes and canals were present, the latter being rare. Many tumor cells, including those with foamy cytoplasm, were positive for glial fibrillary acidic protein. Similar tumor cells were also seen among, and even within, the collagen nodules. The MIB-1 labeling index was 0.66%. Ultrastructurally, the frequent lipidized tumor cells were ependymal in nature; cytoplasmic 10-nm-wide filaments, and intracytoplasmic lumina and intercellular microrosettes lined by microvilli were evident. Cilia were very rare. We considered the present case to be an unusual, lipidized variant of ependymoma. The collagen nodules appeared to be produced by the tumor cells themselves.

Two case reports of sciatica that was considered to be caused by cervical and thoracic spinal cord compression.

This is a retrospective study of the morphologic limitations of posterior decompression for ossification of the posterior longitudinal ligament in the cervical spine.

A multi-quantum-well (MQW) active layer has been introduced to 1.3-μm GaInAsP/InP surface-emitting (SE) lasers. Room temperature pulsed operation of a 1.3-μm MQW SE laser was obtained for the first time and its threshold current was 15 mA. CW (continuous wave) operation up to 7°C (threshold current 1th=7.6 mA at 7°C) was achieved.

Cross-sectional observation of heterointerfaces in a liquid phase epitaxial InP/GaInAsP/InP was performed by electron microscopy. In the high resolution micrographs, a dark band contrast and a spurious image of lattice mismatching were observed at the interface. The anomalies in image contrast are attributed to coherent lattice strains originated from the difference in lattice parameter between InP and GaInAsP and the modulation in GaInAsP epilayer.

We have investigated a double-layer antireflection (AR) coating for semiconductor lasers, which consists of TiO2and SiO2with non-quarter-wave thicknesses. In order to precisely control refractive indices, an electron-beam evaporator with oxygen pressure control was applied. Film thicknesses were accurately measured using the spectroellipsometric technique. Calculations show that the double-layer coating has much enhanced error margins, as well as broader bandwidths, which allows the performance of a double-layer coating even with ±1.6% of thickness errors in both layers to be comparable to or better than that of an ideal single-layer coating. By applying the double-layer coating design to a 1.55 µm GaInAs/AlGaInAs semiconductor laser amplifier, a minimum reflectivity of 5.3×10-3and bandwidths of 140 nm for R<10-3and 31 nm for R<10-4were experimentally obtained.

A 1.59 µm wavelength GaInAsP/InP distributed feedback laser with first-order grating has been fabricated by a two-step liquid phase epitaxial (LPE) growth. The first-order grating was formed on the anti-meltback layer grown on the active layer. The threshold current was 680 mA for 18 µm stripe width and 510 µm cavity length and single-longitudinal-mode operation was obtained from -50 to 0°C.

A GaInAsP/InP laser (?=1.3 µm) with a current blocking layer made by Be implantation has been fabricated. Be-ions were implanted with 70 keV into an n-InP substrate at room temperature and 2.2×1014cm-2of dose. Thermal annealing was applied in a furnace during the LPE (Liquid Phase Epitaxial) growth. The breaking of the forward bias associated with the blocking region was 2 V. The minimum threshold current was 160 mA for 2.5 µm width of waveguide and 250 µm cavity length.