Details of a Researcher - Nakamura, Masaya

Papers - Nakamura, Masaya

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Dorsal shift and expansion of the spinal cord after expansive open-door laminoplasty

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya

J Spinal Disord 10 ( 4 ) 282-287 1997.08

Research paper (scientific journal), Joint Work

胸部椎間板ヘルニアの症候学

Fujimura Yoshikazu, Nakamura Masaya, Matsumoto Morio, Chiba Kazuhiro

脊椎脊髄ジャーナル 10 ( 5 ) 455-460 1997.05

Research paper (scientific journal), Joint Work

MRIによる頚髄不全損傷の経時的評価に関する実験的研究

Oota Keiichi, Fujimura Yoshikazu, Nakamura Masaya, Watanabe Masahiko, Yato Yoshiyuki

日パラプレジア医会誌 10 ( 1 ) 62-63 1997.04

Research paper (scientific journal), Joint Work

頸椎後縦靭帯骨化症における髄内高信号の臨床的意義

Nakamura Masaya, Fujimura Yoshikazu, Matsumoto Morio, Kamata Michihiro, Toyama Yoshiaki, Suzuki Nobumasa

日パラプレジア医会誌 10 ( 1 ) 72-73 1997.04

Research paper (scientific journal), Joint Work

頸椎後縦靭帯骨化症の治療成績と外傷の関連--MRI髄内高信号の臨床的意嚢--

Nakamura Masaya, Fujimura Yoshikazu, Matsumoto Morio, Kamata Michihiro, Toyama Yoshiaki, Suzuki Nobumasa

臨整外 32 ( 4 ) 321-325 1997.04

Research paper (scientific journal), Joint Work

Long-term follow-up study of anterior decompression and fusion for thoracic myelopathy resulting from ossification of the posterior longitudinal ligament

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya, Toyama Yoshiaki, Suzuki Nobumasa

Spine 22 ( 3 ) 305 - 311 1997.02

ISSN 0362-2436

Study Design. This was a retrospective study of the results of anterior decompression and fusion in patients with thoracic myelopathy secondary to ossification of the posterior longitudinal ligament with a minimum follow-up time of 5 years. Objectives. To clarify the effectiveness and limits of anterior decompression and fusion for thoracic ossification of the posterior longitudinal ligament. Summary of Background Data. Posterior decompression for the surgical management of thoracic ossification of the posterior longitudinal ligament has had an uncertain success record. Anterior decompression and fusion have been considered the treatment of choice; however, there are few reports describing the long-term results. Methods. The participants in this investigation were 33 patients whose cases were followed for an average period of 8 years and 2 months. The factors that were investigated included changes in the Japanese Orthopedic Association score and in recovery rates, postoperative complications, and radiographic findings of bone union and progression of ossification of the posterior longitudinal ligament within the area of anterior decompression. Results. Although the recovery rates were relatively stable from 1-5 years after surgery, the rates declined thereafter. The average recovery rate at the final follow-up visit was 53.2%. Postoperative complications included three cases of deterioration of thoracic myelopathy and four cases of extrapleural cerebrospinal fluid leakage. Except for the one case of deterioration of thoracic myelopathy, the remainder of the complications were transient. Conclusions. Anterior decompression and fusion is an effective surgical procedure for thoracic ossification of the posterior longitudinal ligament with good, stable, long- term results; when thoracic ossification of the posterior longitudinal ligament was extensive or coincident with ossification of the intraspinal ligament, however, the results were not as predictable.

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Dorsal shift and expansion of the spinal cord after expansive open-door laminoplasty

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya

Journal of Spinal Disorders 10 ( 4 ) 282 - 287 1997

ISSN 0895-0385

We investigated dorsal shift and anteroposterior spinal cord diameter after expansive open-door laminoplasty, comparing pre- and postoperative computed tomographic myelographic images to clarify the relationships between surgical outcome and these changes. Dorsal shift occurred at the midcervical spine in cervical spondylotic myelopathy (CSM) but was less extensive in ossification of the posterior longitudinal ligament (OPLL). Spinal cord anteroposterior diameter expanded for OPLL but did not for CSM. Correlation of outcome and dorsal shift was not significant for OPLL or CSM. Correlation of outcome and expansion was significant for OPLL, but not for CSM.

Long-term follow-up study of anterior decompression and fusion for thoracic myelopathy resulting from ossification of the posterior longitudinal ligament

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya, Toyama Yoshikazu, Suzuki Nobumasa

Spine 22 ( 3 ) 305-311 1997

Research paper (scientific journal), Joint Work

Decreased choline acetyltransferase activity in the marine spinal cord motoneurons under chronic mechanical compression

Yato Y., Fujimura Y., Nakamura M., Watanabe M., Yabe Y.

Spinal Cord 35 ( 11 ) 729 - 734 1997

ISSN 1362-4393

The tiptoe-walking Yoshimura (twy) mouse is a model of chronic spinal cord compression caused by ossification of intraspinal ligaments. Choline acetyltransferase (CAT), which is known to be a specific marker of cholinergic neurons, best reflects spinal motoneuron function. Changes in CAT immunoreactivity following chronic spinal cord compression in twy mice were investigated quantitatively in order to elucidate spinal motoneuron functional changes according to the degree and direction of compression. Thirty 24-week-old twy mice were used in this study. They were divided into three groups according to the direction of spinal cord compression (anterior, posterior, and lateral) and the CAT immunoreactivities in whole sections of their upper cervical spinal cords were investigated quantitatively using a fluorescence microphotometry system. The lateral compression group showed histological spinal motoneuron atrophy and loss on the compressed, but not the non-compressed, side. Spinal motoneuron atrophy and loss were observed when the severity of spinal canal stenosis due to the ossified lesion, expressed as the occupation rate, was 30% or more, but the spinal motoneurons appeared normal when it was below 30%. The CAT immunofluorescence intensity of the anterior horn showed a linear negative correlation with the degree of canal stenosis. When the occupation rate was below 20%, the CAT immunofluorescence intensities in the anterior horns of the compression and control groups did not differ significantly. The CAT immunofluorescence intensity of twy mice with occupation rates of 20% or more were significantly lower than that of those with occupation rates below 20%. Furthermore, the CAT immunofluorescence intensity was significantly lower on the compressed than the noncompressed side of the lateral compression group. Thus, our findings indicate that an occupation rate of about 20% may be the critical level for functional changes in the spinal motoneurons.

Muscle reorganization following incomplete cervical spinal cord injury in rats

Nakamura M., Fujimura Y., Yato Y., Watanabe M.

Spinal Cord 35 ( 11 ) 752 - 756 1997

ISSN 1362-4393

This study on rats was designed to evaluate the change of biceps muscle fibers by enzyme histochemical examination and the change of distribution of motoneurons innervating biceps muscle fibers by retrograde tracer examination after incomplete spinal cord injury. Incomplete spinal cord injury was produced by placing a 20 g weight on exposed dura at the C6 level. The number of the labeled motoneurons of C6 segment significantly decreased compared with that in the control, but there were no significant changes in the other segments at 4 weeks after the injury. Moreover, there was type grouping of biceps muscle fibers at 4 weeks after the injury. These findings indicated that the incomplete cervical spinal cord injury at C6 level in rats caused the partial denervation and then reinnervation of biceps muscle fibers by the collateral sprouting of the remaining motoneurons which belonged to the same motoneuron pool of the injured motoneurons.

Myelopathy secondary to ossification of the posterior longitudinal ligament of the thoracic spine treated by anterior decompression and bony fusion

Fujimura Y., Nishi Y., Nakamura M., Watanabe M., Matsumoto M.

Spinal Cord 35 ( 11 ) 777 - 784 1997

ISSN 1362-4393

We examined the utility of anterior decompression and bony fusion via the extrapleural approach in the treatment of thoracic myelopathy secondary to ossification of the posterior longitudinal ligament (OPLL). Patient outcome and complications were analyzed in 48 patients treated with this procedure, with a follow-up of at least 2 years. The Japanese Orthopaedic Association score was used to evaluate the severity of the thoracic myelopathy, and the recovery rate was used to evaluate the surgical outcome. The outcome, postoperative complications, radiographic evaluations of bony union, and progression of OPLL within the area of anterior decompression were examined. The T3 vertebral body was the highest level to which anterior decompression was applied. The average follow-up period was 57 months with a recovery rate of 56.7% which stabilized 1 year after operation. However, the surgical outcome was less favorable in patients with long-standing myelopathy, extensive OPLL, or thoracic OPLL with coexisting intraspinal ligament ossification. Four patients experienced deterioration of their myelopathy, and seven patients had the postoperative complication of extraspinal leakage of cerebrospinal fluid. The myelopathy was transient in all but one patient. Radiographic studies showed that bony union was achieved and restenosis of the spinal canal due to progression of OPLL within the area of decompression did not occur. We conclude that anterior decompression and bony fusion using the extrapleural approach provides a good outcome and is useful in treating mid- and lower thoracic OPLL when performed carefully at an early stage of disease.

Changes in choline acetyltransferase activity and distribution following incomplete cervical spinal cord injury in the rat

Nakamura M., Fujimura Y., Yato Y., Watanabe M., Yabe Y.

Neuroscience 75 ( 2 ) 481 - 494 1996.10

ISSN 0306-4522

Incomplete cervical spinal cord injuries were produced in rats by placing 10 g or 20 g weight on exposed dura at the C6 level for 5 min (Mild or Moderate injury). These two degrees of the injury resulted in initial motor functional deficits, followed by recoveries. In this study, changes in choline acetyltransferase activity and distribution following the incomplete cervical cord injuries were investigated using radioenzyme assay, and fluorescence microphotometry. We demonstrated that mild injury led to a transient decrease of choline acetyltransferase activity in the compressed spinal cord segment, but showed almost no histologic change at two days after injury. Although a low level of choline acetyltransferase immunofluorescence was found in the ventrolateral anterior horn at two days after injury, it recovered completely by one week after injury. These findings suggest that there was a strong correlation between the transient motor functional deficit and the decrease in choline acetyltransferase activity following mild injury. Moderate injury resulted in a persistent low level of choline acetyltransferase activity in the compressed spinal cord segment accompanied by a striking loss of gray matter. On the other hand, at seven, 14 and 28 days after injury, over-expression of choline acetyltransferase activity was found in the neighboring spinal cord segments located both rostral and caudal to the injury, which showed no histologic change. In addition, excessively high levels of choline acetyltransferase immunofluorescence were found in the ventrolateral anterior horn of these segments. A strong correlation was found between the motor functional recovery and the late, e high levels of choline acetyltransferase activity in the neighboring regions. These results suggest that cholinergic neurons, especially spinal motor neurons may play an important role in the motor functional recovery following incomplete cervical spinal cord injury.

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Metastases to the upper cervical spine

Nakamura Masaya, Toyama Yoshiaki, Suzuki Nobumasa, Fujimura Yoshikazu

Journal of Spinal Disorders 9 ( 3 ) 195 - 201 1996

ISSN 0895-0385

A retrospective study of 13 patients with metastases to the upper cervical spine was designed to examine the clinical efficacy of surgical treatment. All patients had severe neck pain and two had quadriplegia. Eleven patients underwent operative posterior stabilization, and two patients were treated with a brace and radiotherapy. Pain relief after surgery was significant so that 10 of the 11 patients could leave bed and resume their normal activities. The other two patients who were treated nonoperatively had severe dementia and sudden death from a respiratory arrest after a fall, despite temporary relief from pain. Surgery may be very successful in improving the quality of life of patients who have pain and/or paralysis caused by metastases to the upper cervical spine.

Anterior decompression and fusion for ossification of the posterior longitudinal ligament of the upper thoracic spine causing myelopathy ; using the manubrium splitting approach

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya, Toyama Yoshiaki, Suzuki Nobumasa

Spinal Cord 34 ( 7 ) 387-393 1996

Research paper (scientific journal), Joint Work

Metastases to the upper cervical spine

Nakamura Masaya, Fujimura Yoshikazu, Toyama Yoshiaki, Suzuki Nobumasa

J Spinal Disord 9 ( 4 ) 195-201 1996

Research paper (scientific journal), Joint Work

Changes in choline acetyltransferase activity and distribution following incomplete cervical spinal cord injury in the rat

Nakamura Masaya, Fujimura Yoshikazu, Yato Yoshiyuki, Watanabe Masahiko, Yabe Yutaka

Neuroscience 75 ( 2 ) 481-494 1996

Research paper (scientific journal), Joint Work

頚椎後縦靭帯骨化症の手術治療成績と外傷の関連について

Nakamura Masaya, Fujimura Yoshikazu, Matsumoto Morio, Kamata Michihiro, Toyama Yoshiaki, Suzuki Nobumasa

臨整外 31 ( 12 ) 1339-1342 1996

Research paper (scientific journal), Joint Work

慢性脊髄圧迫による前角細胞の機能的変化

Yato Yoshiyuki, Fujimura Yoshikazu, Nakamura Masaya, Watanabe Masahiko

日パラ医誌 9 ( 1 ) 62-63 1996

Research paper (scientific journal), Joint Work

Anterior decompression and fusion for ossification of the posterior longitudinal ligament of the upper thoracic spine causing myelopathy

Fujimura Y., Nishi Y., Nakamura M., Toyama Y., Suzuki N.

Spinal Cord 34 ( 7 ) 387 - 393 1996

ISSN 1362-4393

The effectiveness and problems associated with the operation of anterior decompression and fusion using the manubrium splitting approach for thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL) of the upper thoracic spine carried out in nine patients was investigated. They were followed up for 1 year or more following the operation. The severity of the thoracic myelopathy was evaluated using the Japanese Orthopaedic Association score, and the surgical outcome was evaluated using recovery rates. This study includes investigation of the surgical outcome and of any postoperative complications, and radiographic observation of bony union and the progression of OPLL within the area of the anterior decompression. The caudal limit of the anterior decompression achieved by splitting the manubrium was the T3 vertebral body. A recovery rate of 71% was achieved during an average follow-up period of 35 months. Only one transient recurrent nerve palsy, and in another patient cerebrospinal fluid leakage occurred as postoperative complications. Radiographic examinations confirmed bony union in all of the patients, and there was no instance of spinal canal stenosis caused by progression of the OPLL within the area of the anterior decompression. Anterior decompression and fusion by splitting the manubrium was an effective surgical procedure for OPLL of the upper thoracic spine, to achieve a good outcome, however, the extent of anterior decompression was limited.

後弯変形による頚椎症性筋萎縮症の2例

Nakamura Masaya, Toyama Yoshiaki, Kohno Toru, Hiraishi Eiichi, Kihara Michiya, Akasaka Keijiro

整形外科 46 ( 7 ) 841-845 1995.07

Research paper (scientific journal), Joint Work

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