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  • Journal of Neurosurgery: Spine x
  • By Author: Nakamura, Masaya x
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Sanjeev Ariyandath Sreenivasan, Kanwaljeet Garg, Manmohan Singh and Poodipedi Sarat Chandra

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Satoshi Nori, Akio Iwanami, Akimasa Yasuda, Narihito Nagoshi, Nobuyuki Fujita, Tomohiro Hikata, Mitsuru Yagi, Takashi Tsuji, Kota Watanabe, Suketaka Momoshima, Morio Matsumoto, Masaya Nakamura and Ken Ishii

OBJECTIVE

A number of studies have reported that surgery for cervical intramedullary tumors via the posterior approach can result in postoperative sagittal malalignment of the cervical spine; however, the risk factors remain unclear. The purpose of this study was to investigate the changes in cervical spinal alignment after surgery for cervical intramedullary tumors in adults and to elucidate the risk factors for cervical spinal sagittal misalignment.

METHODS

Data for the period from April 2001 to December 2011 for all adults who had undergone surgery for cervical intramedullary spinal cord tumors at a single institution were retrospectively analyzed to determine the postoperative changes in cervical spine alignment. Patients younger than 20 years of age and those who required postoperative radiotherapy were excluded from the study. Patients were divided into 2 groups according to tumor location: upper tumor (U) group, in which the central region of the tumor was above the C-5 level; and lower tumor (L) group, in which the central region of the tumor was at or below the C-5 level. Changes in alignment of the cervical spine were measured on plain lateral radiographs. Data on atrophy of the deep extensor muscles (DEMs), tumor location, detachment of the DEMs from the C-2 spinous process, the C2–7 angle before surgery, patient age at surgery, tumor histology, patient sex, tumor size, and number of laminae affected were reviewed for each patient, and the correlation of each of these factors with cervical spinal malalignment was evaluated using statistical analysis.

RESULTS

The 54 adults eligible for analysis had a mean age of 49.1 years. Ependymoma was the most common cervical intramedullary tumor (63.0%) in this series. In the tumor location U group, the kyphotic angle of the C2–7 spinal segments increased after surgery (−5.8° ± 2.8°). In contrast, in the L group, the C2–7 lordotic angle increased after surgery (6.4° ± 2.6°). In the univariate analysis, atrophy of the DEMs, detachment of the DEMs from the C-2 spinous process, and an upper cervical location of the tumor were identified as factors significantly correlated with the development of cervical spinal kyphosis after surgery. Multiple linear regression analysis revealed the following as risk factors for kyphotic change of the cervical spine after surgery: 1) atrophy of the DEMs after surgery (β = −0.54, p < 0.01), and 2) detachment of the DEMs from the C-2 spinous process (β = −0.37, p < 0.01).

CONCLUSIONS

Atrophy of the DEMs after surgery and detachment of the DEMs from the C-2 spinous process are directly related to the risk of cervical spinal kyphosis after surgery for cervical intramedullary tumors in adults. Therefore, preservation of the DEMs, especially those attached to the C-2 spinous process, is important for the prevention of kyphotic malalignment of the cervical spine after surgery for intramedullary tumors.

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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.

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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.

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Masaya Nakamura, Kanehiro Fujiyoshi, Osahiko Tsuji, Tsunehiko Konomi, Naobumi Hosogane, Kota Watanabe, Takashi Tsuji, Ken Ishii, Suketaka Momoshima, Yoshiaki Toyama, Kazuhiro Chiba and Morio Matsumoto

Object

This study was conducted to determine whether postoperative changes in the fractional anisotropy (FA) value and diffusion tensor imaging of the cervical spinal cord can predict functional outcome for patients with cervical compressive myelopathy (CCM).

Methods

Twenty patients with CCM were treated by laminoplasty from 2008 to 2009. Both T2-weighted MRI and diffusion tensor imaging were performed before and after surgery. The FA values were analyzed and fiber tracking was performed. The fiber tract (FT) ratio was calculated according to the following formula: (number of fibers at the compressed level)/(number of fibers at the C-2 level) × 100%. The Japanese Orthopaedic Association scoring system for cervical myelopathy was used to determine pre- and postoperative neurological status of the patients, and the Hirabayashi method was used to calculate the recovery rate.

Results

There was no significant difference in recovery rates between patients with and those without intramedullary high signal intensity on preoperative T2-weighted images. Substantial differences in FA value among spinal cord, bone, and CSF made it difficult to obtain a precise FA value for the compressed spinal cord. There was a significant correlation between the preoperative FT ratio and the recovery rate (p = 0.0006). A poor outcome (recovery rate < 40%) could be anticipated for CCM patients with preoperative FT ratios below 60%.

Conclusions

The preoperative FT ratio correlated significantly with the recovery rates in CCM patients. Preoperative diffusion tensor tractography can be a new prognostic predictor for neurological recovery in CCM patients after laminoplasty.

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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.

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Kota Watanabe, Morio Matsumoto, Takeshi Ikegami, Yuji Nishiwaki, Takashi Tsuji, Ken Ishii, Yuto Ogawa, Hironari Takaishi, Masaya Nakamura, Yoshiaki Toyama and Kazuhiro Chiba

Object

To reduce intraoperative damage to the posterior supporting structures of the lumbar spine during decompressive surgery for lumbar canal stenosis (LCS), lumbar spinous process–splitting laminectomy (LSPSL or split laminectomy) was developed. This prospective, randomized, controlled study was conducted to clarify whether the split laminectomy decreases acute postoperative wound pain compared with conventional laminectomy.

Methods

Forty-one patients with LCS were enrolled in this study. The patients were randomly assigned to either the LSPSL group (22 patients) or the conventional laminectomy group (19 patients). Questionnaires regarding wound pain (intensity, depth, and duration) and activities of daily living (ADL) were administered at postoperative days (PODs) 3 and 7. Additionally, the authors evaluated the pre- and postoperative serum levels of C-reactive protein and creatine phosphokinase, the amount of pain analgesics used during a 3-day postoperative period, and the muscle atrophy rate measured on 1-month postsurgical MR images.

Results

Data obtained in patients in the LSPSL group and in 16 patients in the conventional laminectomy group were analyzed. The mean visual analog scale for wound pain on POD 7 was significantly lower in the LSPSL group (16 ± 17 mm vs 34 ± 31 mm, respectively; p = 0.04). The mean depth-of-pain scores on POD 7 were significantly lower in the LSPSL group than in the conventional group (0.9 ± 0.6 vs 1.7 ± 0.8, respectively; p = 0.013). On POD 3, the mean serum creatine phosphokinase level was significantly lower in the LSPSL group (126 ± 93 U/L) than in the other group (207 ± 150 U/L) (p = 0.02); on POD 7, the mean serum C-reactive protein level was significantly lower in the LSPSL group (1.1 ± 0.6 mg/dl) than in the conventional laminectomy group (1.9 ± 1.5 mg/dl) (p = 0.04). The number of pain analgesics taken during the 3-day postoperative period was lower in the LSPSL group than in the conventional laminectomy group (1.7 ± 1.3 tablets vs 2.3 ± 2.4 tablets, respectively; p = 0.22). The mean muscle atrophy rate was also significantly lower in the LSPSL group (24% ± 15% vs 43% ± 22%; p = 0.004).

Conclusions

Lumbar spinous process–splitting laminectomy for the treatment of LCS reduced acute postoperative wound pain and prevented postoperative muscle atrophy compared with conventional laminectomy, possibly because of minimized damage to the paraspinal muscles.

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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.

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

Object

The aim in this study was to evaluate the efficacy of the ball tip technique in placing thoracic pedicle screws (TPSs), as compared with the conventional freehand technique, in both a cadaveric study and a clinical study of patients with adolescent idiopathic scoliosis. Although posterior spinal surgery using TPSs has been widely applied, these screws are associated with the potential risk of vascular, pulmonary, or neurological complications. To further enhance the accuracy and safety of TPS placement, the authors developed the ball tip technique.

Methods

After creating an appropriate starting point for probe insertion, a specially designed ball tip probe consisting of a ball-shaped tip with a flexible metal shaft is used to make a guide hole into the pedicle. Holding the probe with the fingertips while using an appropriate amount of pressure or by tapping it gently and continuously with a hammer, one can safely insert the ball tip probe into the cancellous channel in the pedicle.

In a cadaveric study, 5 spine fellows with similar levels of experience in placing TPSs applied the ball tip or the conventional technique to place screws in 5 cadavers with no spinal deformities. The incidence of misplaced screws was evaluated by dissecting the spines. In a clinical study, 40 patients with adolescent idiopathic scoliosis underwent posterior surgery with TPS placement via the ball tip or conventional technique (20 patients in each treatment group). The accuracy of the TPS placements was evaluated on postoperative axial CT scanning.

Results

In the cadaveric study, 100 TPSs were evaluated, and the incidence of misplaced screws was 14% in the ball tip group and 34% in the conventional group (p = 0.0192). In the clinical study, 574 TPSs were evaluated. One hundred seventy-one intrapedicular screws (67%) were recognized in the conventional group and 288 (90%) in the ball tip group (p < 0.01). In the conventional and ball tip groups, the respective numbers of TPSs with a pedicle breach of ≤ 2 mm were 20 (8%) and 15 (5%), those with a pedicle breach of > 2 mm were 32 (13%) and 9 (3%; p < 0.01), and those located in the costovertebral joints were 32 (13%) and 7 (2%).

Conclusions

In both cadaveric and clinical studies the ball tip technique enhanced the accuracy of TPS placement as compared with the conventional freehand technique. Thus, the ball tip technique is useful for the accurate and safe placement of TPSs in deformed spines.

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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.