Search Results

You are looking at 1 - 10 of 24 items for

  • Author or Editor: Masaya Nakamura x
Clear All Modify Search
Restricted access

Yuji Mikami, Masahiro Toda, Masahiko Watanabe, Masaya Nakamura, Yoshiaki Toyama and Yutaka Kawakami

✓ To establish a simple and reliable method to assess the behavioral function after spinal cord injury (SCI) in mice, the authors used an automated animal movement analysis system, SCANET.

Two different SCI lesions were created in adult female BALB/c and C57BL/6 mice by transecting both the posterior columns and the left lateral and anterior funiculi or only the left lateral and anterior funiculi at T-8. Control mice underwent laminectomy only. The SCANET system consists of a cage equipped with two crossing sensor frames arranged at different heights, by which small (M1) and large (M2) horizontal movements and the vertical movement involved in rearing (RG) can be monitored. The authors assessed locomotor function by determining the M1, M2, and RG scores; to this end, they used the SCANET system and a previously established behavior test, the 21-point open-field Basso-Beattie-Bresnahan (BBB) Locomotor Rating Scale. The results indicated that the RG scores were significantly and consistently different between the spinal cord—injured and control mice, irrespective of the mouse strain or injury model, but that M1 and M2 scores were not. Moreover, there was a statistically positive correlation between the RG score and the BBB Scale score.

For the assessment of locomotor function after SCI, use of the SCANET sytem in behavioral analysis is simple and the method is highly reproducible. The analysis of vertical movement is useful for assessing the recovery of limb function in mice following thoracic hemisection.

Restricted access

Masaya Nakamura, Kazuhiro Chiba, Takashi Nishizawa, Hirofumi Maruiwa, Morio Matsumoto and Yoshiaki Toyama

Object. Pain is one of the major symptoms in patients with syringomyelia; however, its origin is not fully understood, and postoperative improvement of pain is difficult to predict. The objectives of this study were to assess the surgery-related results obtained in patients who underwent treatment for syringomyelia associated with Chiari I malformation, particularly related to pain status, and to identify factors that may influence improvement in postoperative pain by comparing pre- and postoperative magnetic resonance (MR) imaging findings.

Methods. The correlation between pre- and postoperative changes in the size and the location of the syrinx and pain improvement was investigated in 25 patients. The shapes of the syringes were classified into three types: central, enlarged, and deviated. In most cases in which the syrinx deviated toward the posterolateral aspect of the spinal cord at the level corresponding to dermatomal distribution of preoperative pain, the lesion remained at the same position postoperatively, and improvement in pain was poor. On the other hand, enlarged-type syringes were the most frequently observed prior to surgery, exhibited diverse changes postoperatively, and improvement in pain status was difficult to predict. When postoperative MR imaging revealed a transformation to the deviated type, poor pain improvement was noted.

Conclusions. Neurons in the dorsal horn were thought to be involved in the development of pain as a result of the deafferentiation mechanism in cases of syringomyelia.

Restricted access

Morio Matsumoto, Kazuhiro Chiba, Masaya Nakamura, Yuto Ogawa, Yoshiaki Toyama and Jun Ogawa

Object. Structural interlaminar graft materials were used for atlantoaxial transarticular screw fixation (TSF), and its impact on the fusion status was investigated.

Methods. Forty-two patients (10 men, 32 women, mean age 51 years, mean follow-up period 45 months; 30 with rheumatoid arthritis, and 12 with os odontoideum) underwent TSF and modified Brooks posterior wiring involving titanium cables. As interlaminar graft materials, autologous bone from posterior iliac crest alone was used in 20 patients (Group A), and a structural spacer (13 ceramic spacers, nine titanium mesh cages) in 22 (Group B). Lateral radiographs were evaluated to determine bone fusion, alignment of the cervical spine, and wire loosening. Solid osseous fusion was obtained in 95% of Group A and 96% of Group B patients. The mean atlantoaxial angle was 19.1 ± 9.7° and 16.7 ± 10.4° before surgery (p = 0.45), and 27.4± 7.8° and 22.1 ± 5.5° after surgery (p = 0.02) in Groups A and B, respectively. Atlantoaxial hyperlordosis (atlantoaxial angle ≥ 30°) was observed in 32% of Group A and 18% of Group B patients (p = 0.26). Postoperative kyphosis occurred in 40% of Group A and 23% of Group B patients (p = 0.28). Loosening of the cable was demonstrated in 50% of Group A and 36% of Group B patients (p = 0.37). In Group B patients maintenance of cervical lordosis was more likely than in those in Group A, although the differences did not reach statistical significance.

Conclusions. These results indicate that structural interlaminar spacers can maintain proper cervical alignment without a decease in the fusion rate; the authors recommend their use in conjunction with TSF.

Restricted access

Morio Matsumoto, Kota Watanabe, Takashi Tsuji, Ken Ishii, Masaya Nakamura, Kazuhiro Chiba and Yoshiaki Toyama

Object

The object of this study was to investigate failures after spinal reconstruction following total en bloc spondylectomy (TES), related factors, and sequelae arising from such failures in patients with malignant spinal tumors.

Methods

Fifteen patients (12 males and 3 females, with a mean age of 46.5 years) with malignant spinal tumors who underwent TES and survived for more than 1 year were included in this analysis (mean follow-up 41.5 months). Seven patients had primary tumors, including giant cell tumors in 4 patients, chordoma in 2, and Ewing sarcoma in 1. Eight patients had metastatic tumors, including thyroid cancer in 6 and renal cell cancer and malignant fibrous histiocytoma in 1 patient each. Seven patients without prominent paravertebral extension of the tumor were treated using a posterior approach alone, and 8 patients who exhibited prominent anterior or anterolateral extension of the tumors into the thoracic or abdominal cavity were treated using a combined anterior and posterior approach. Spinal reconstruction after tumor resection was performed using a combination of anterior structural support and posterior instrumentation. The relationship between instrumentation failure and clinical and radiographic factors, including age, sex, history of previous surgery, preoperative radiotherapy, tumor histology, tumor level, surgical approach, number of resected vertebrae, rod diameter, number of instrumented vertebrae, and cage subsidence, was investigated.

Results

Six patients (40%) with spinal instrumentation failure were identified: rod breakage occurred in 3 patients, and breakage of both the rod and the cage, combined cage breakage and screw back-out, and endplate fracture arising from cage subsidence occurred in 1 patient each. All of these patients experienced acute or chronic back pain, but only 1 patient with a tumor recurrence experienced neurological deterioration upon instrumentation failure. Cage subsidence (≥ 5 mm), preoperative irradiation, and the number of instrumented vertebrae (≤ 4 vertebrae) were significantly related to late instrumentation failure.

Conclusions

Late instrumentation failure was a frequent complication after TES. Although patients with instrumentation failure experienced back pain, the neurological sequelae were not catastrophic. For prevention, meticulous preparation of the graft site and a longer posterior fixation should be considered.

Restricted access

Masaya Nakamura, Kazuhiro Chiba, Morio Matsumoto, Eiji Ikeda and Yoshiaki Toyama

✓ The authors present clinical, radiological, and pathological features in a patient with a pleomorphic xanthoastrocytoma (PXA) of the spinal cord. To their knowledge, this is only the second report of a spinal cord PXA. In addition they perform a review of the literature on these tumors.

Restricted access

Kenya Nojiri, Morio Matsumoto, Kazuhiro Chiba, Hirofumi Maruiwa, Masaya Nakamura, Takashi Nishizawa and Yoshiaki Toyama

Object

The aim of this study was to establish standard values for the normal alignment of the upper cervical spine and to clarify its relationship with the lower cervical spine in terms of alignment.

Methods

Three hundred thirteen asymptomatic volunteers (155 men and 158 women) participated in this study. Lateral radiographs were obtained with the neck in neutral position, and the angles formed by the occiput (Oc) and the axis, the atlas and the axis, and C-2 to C-7 were measured. The mean Oc—C2 angle was 14.5 ± 8° in men and 16 ± 8.5° in women; the mean C1–2 angle was 26.5 ± 7° and 28.9 ± 6.7°, respectively; and the mean C2–7 angle was 16.2 ± 12.9° and 10.5 ± 10.3°, respectively. Although weak, statistically significant negative correlation was observed between Oc—C2 and C2–7 angles (r = −0.31 in men and −0.37 in women), and between C1–2 and C2–7 angles (r = −0.22 in men and −0.22 in women). The correlation coefficient between the Oc—C2 and C2–7 angles was greater than that between the C1–2 and C2–7 angles.

Conclusions

Such relationships between alignment of the upper and lower cervical spines should be taken into consideration when performing occipitocervical fusion.

Restricted access

Soya Kawabata, Kota Watanabe, Naobumi Hosogane, Ken Ishii, Masaya Nakamura, Yoshiaki Toyama and Morio Matsumoto

Severe cervical kyphosis requiring surgical treatment is rare in patients with neurofibromatosis Type 1 (NF1). When it occurs, however, dystrophic changes in the vertebrae make surgical correction and fusion of the deformity extremely difficult.

The authors report on 3 cases of severe cervical kyphosis associated with NF1 that were successfully treated with combined anterior and posterior correction and fusion. All patients underwent halo-gravity traction for approximately 1 month prior to surgery to correct the deformity gradually. Posterior correction and fusion were performed with segmental spinal instrumentation consisting of lateral mass screws, lamina screws, pedicle screws, and polyethylene tape for sublaminar wiring. Anterior spinal fusion was performed using a fibula strut to induce solid bone fusion. All patients used a halo vest for postoperative external fixation.

Preoperative CT scans showed dystrophic cervical spine changes, and MR images demonstrated extensive neurofibromas outside the cervical spine in all 3 patients. The preoperative kyphotic angles were as follows: Case 1, 140°; Case 2, 81°; and Case 3, 72°; after halo-gravity traction, the kyphosis angles improved to 50°, 55°, and 51°, respectively; and after surgery, they were 50°, 15°, and 27°, respectively. Solid bone union was observed in all patients at the latest follow-up. All three patients experienced postoperative complications consisting of superficial infection, severe pneumonia, and partial dislocation of the distal fibula graft after removing the halo vest, in one patient each.

Although dystrophic cervical vertebral changes in these patients with NF1 complicated the correction of severe cervical kyphosis, the use of preoperative halo-gravity traction, a combination of spinal instrumentations, an anterior strut bone graft, and postoperative halo-vest fixation made it possible to correct the kyphosis, maintain the correction, and achieve solid bone fusion.

Restricted access

Morio Matsumoto, Kota Watanabe, Ken Ishii, Takashi Tsuji, Hironari Takaishi, Masaya Nakamura, Yoshiaki Toyama and Kazuhiro Chiba

Object

In this paper, the authors' goal was to elucidate the clinical features and results of decompression surgery for extraforaminal stenosis at the lumbosacral junction.

Methods

Twenty-eight patients with severe leg pain caused by extraforaminal stenosis at the lumbosacral junction (18 men and 10 women; mean age 68.2 ± 8.9 years) were treated by posterior decompression without fusion using a microendoscope in 19 patients and a surgical microscope or loupe in 9 patients. The decompression procedures consisted of partial resection of the sacral ala, the L-5 transverse process, and the L5–S1 facet joint along the L-5 spinal nerve. The following items were investigated: 1) preoperative neurological findings; 2) preoperative radiological findings, including plain radiographs, CT scans, selective radiculography of L-5; 3) surgical outcome as evaluated using the Japanese Orthopaedic Association scale for low-back pain (JOA score); and 4) need for revision surgery.

Results

All patients presented with neurological deficits compatible with a diagnosis of L-5 radiculopathy such as weakness of the extensor hallucis longus muscle and sensory disturbance in the L-5 area together with neurogenic claudication. On plain radiographs, 21 patients (75%) and 17 patients (60.7%) exhibited lumbar scoliosis (≥ 5°) and wedging of the L5–S1 intervertebral space (≥ 3°), respectively. The CT scans demonstrated marked osteophyte formation at the posterolateral margin of the L5–S1 vertebral bodies, and a selective L-5 nerve root block was effective in all patients. All patients reported pain relief immediately after surgery. The mean JOA scores were 11.3 ± 3.8 before surgery and 24.3 ± 3.4 at the time of the final follow-up examination; the recovery rate was 68.6 ± 16.5%. The mean estimated blood loss was 66.6 ± 98.6 ml, and the mean surgical time was 135.3 ± 46.5 minutes. No significant difference in the recovery rate of the JOA scores or in the surgical time and blood loss was observed between the 2 surgical approaches. Four patients underwent revision posterior interbody fusion for the recurrence of radicular pain as a result of intraforaminal stenosis in 3 patients and insufficient decompression of the extraforaminal area in the remaining patient at an average of 19.5 months after surgery.

Conclusions

Extraforaminal stenosis at the lumbosacral junction is a rare but distinct pathological condition causing L-5 radiculopathy. Decompression surgery without fusion using a microendoscope or a surgical microscope/ loupe is a feasible and less invasive surgical option for elderly patients with extraforaminal stenosis at the lumbosacral junction.

Full access

Tomohiro Hikata, Kota Watanabe, Nobuyuki Fujita, Akio Iwanami, Naobumi Hosogane, Ken Ishii, Masaya Nakamura, Yoshiaki Toyama and Morio Matsumoto

OBJECT

The object of this study was to investigate correlations between sagittal spinopelvic alignment and improvements in clinical and quality-of-life (QOL) outcomes after lumbar decompression surgery for lumbar spinal canal stenosis (LCS) without coronal imbalance.

METHODS

The authors retrospectively reviewed data from consecutive patients treated for LCS with decompression surgery in the period from 2009 through 2011. They examined correlations between preoperative or postoperative sagittal vertical axis (SVA) and radiological parameters, clinical outcomes, and health-related (HR)QOL scores in patients divided according to SVA. Clinical outcomes were assessed according to Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores. Health-related QOL was evaluated using the Roland-Morris Disability Questionnaire (RMDQ) and the JOA Back Pain Evaluation Questionnaire (JOABPEQ).

RESULTS

One hundred nine patients were eligible for inclusion in the study. Compared to patients with normal sagittal alignment prior to surgery (Group A: SVA < 50 mm), those with preoperative sagittal imbalance (Group B: SVA ≥ 50 mm) had significantly smaller lumbar lordosis and thoracic kyphosis angles and larger pelvic tilt. In Group B, there was a significant decrease in postoperative SVA compared with the preoperative SVA (76.3 ± 29.7 mm vs 54.3 ± 39.8 mm, p = 0.004). The patients in Group B with severe preoperative sagittal imbalance (SVA > 80 mm) had residual sagittal imbalance after surgery (82.8 ± 41.6 mm). There were no significant differences in clinical and HRQOL outcomes between Groups A and B. Compared to patients with normal postoperative SVA (Group C: SVA < 50 mm), patients with a postoperative SVA ≥ 50 mm (Group D) had significantly lower JOABPEQ scores, both preoperative and postoperative, for walking ability (preop: 36.6 ± 26.3 vs 22.7 ± 26.0, p = 0.038, respectively; postop: 71.1 ± 30.4 vs 42.5 ± 29.6, p < 0.001) and social functioning (preop: 38.7 ± 18.5 vs 30.2 ± 16.7, p = 0.045; postop: 67.0 ± 25.8 vs 49.6 ± 20.0, p = 0.001), as well as significantly higher postoperative RMDQ (4.9 ± 5.2 vs 7.9 ± 5.7, p = 0.015) and VAS scores for low-back pain (2.68 ± 2.69 vs 3.94 ± 2.59, p = 0.039).

CONCLUSIONS

Preoperative sagittal balance was not significantly correlated with clinical or HRQOL outcomes after decompression surgery in LCS patients without coronal imbalance. Decompression surgery improved the SVA value in patients with preoperative sagittal imbalance; however, the patients with severe preoperative sagittal imbalance (SVA > 80 mm) had residual imbalance after decompression surgery. Both clinical and HRQOL outcomes were negatively affected by postoperative residual sagittal imbalance.

Restricted access

Masaya Nakamura, Osahiko Tsuji, Kanehiro Fujiyoshi, Kota Watanabe, Takashi Tsuji, Ken Ishii, Morio Matsumoto, Yoshiaki Toyama and Kazuhiro Chiba

Object

The optimal management of malignant astrocytomas remains controversial, and the prognosis of these lesions has been dismal regardless of the administered treatment. In this study the authors investigated the surgical outcomes of cordotomy in patients with thoracic malignant astrocytomas to determine the effectiveness of this procedure.

Methods

Cordotomy was performed in 5 patients with glioblastoma multiforme (GBM) and 2 with anaplastic astrocytoma (AA). A Kaplan-Meier survival analysis was performed, and the associations of the resection level with survival and postoperative complications were retrospectively examined.

Results

Cordotomy was performed in a single stage in 2 patients with GBM and in 2 stages in 3 patients with GBM and 2 patients with AA. In the 2 patients with GBM, cordotomy was performed 2 and 3 weeks after a partial tumor resection. In the 2 patients with AA, the initial treatment consisted of partial tumor resection and subtotal resection combined with radiotherapy, and rostral tumor growth and progressive paralysis necessitated cordotomy 2 and 28 months later. One patient with a secondary GBM underwent cordotomy; the GBM developed 1 year after subtotal resection and radiotherapy for a WHO Grade II astrocytoma. Four patients died 4, 5, 24, and 42 months after the initial operation due to CSF dissemination, and 3 patients (2 with GBM and 1 with AA) remain alive (16, 39, and 71 months). No metastasis to any other organs was noted.

Conclusions

One-stage cordotomy should be indicated for patients with thoracic GBM or AA presenting with complete paraplegia preoperatively. In patients with thoracic GBM, even if paralysis is incomplete, cordotomy should be performed before the tumor disseminates through the CSF. Radical resection should be attempted in patients with AA and incomplete paralysis. If the tumor persists, radiotherapy and chemotherapy are indicated, and cordotomy should be reserved for lesions growing progressively after such second-line treatments.