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Toshimi Aizawa, Toshimitsu Eto, Ko Hashimoto, Haruo Kanno, Eiji Itoi, and Hiroshi Ozawa

OBJECTIVE

Thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) remains one of the most difficult-to-treat disorders for spine surgeons. In Japan, approximately 75% of patients with this condition are treated using posterior decompression with instrumented spinal fusion (PDF). In contrast, anterior decompression is the most effective method for relieving spinal cord compression. The authors treated nonambulatory patients with thoracic OPLL by either PDF or by their technique using anterior decompression through a posterior approach. In this study the surgical results of these procedures are compared.

METHODS

This was a retrospective case series. From 2008 to 2018, 9 patients with thoracic OPLL who could not walk preoperatively were treated surgically. Three patients were treated by PDF (the PDF group) and 6 patients were treated by anterior decompression through a posterior approach (the modified Ohtsuka group). The degree of surgical invasion and the neurological conditions of the patients were assessed.

RESULTS

The PDF group had a shorter operative duration (mean 477 ± 122 vs 569 ± 92 minutes) and less intraoperative blood loss (mean 613 ± 380 vs 1180 ± 614 ml), although the differences were not statistically significant. The preoperative Japanese Orthopaedic Association (JOA) score was almost identical between the two groups; however, the latest JOA score and the recovery rate were significantly better in the modified Ohtsuka group than in the PDF group (8.8 ± 1.5 vs 5.0 ± 1.7 and 71.3% ± 23.7% vs 28.3% ± 5.7%, respectively). The walking ability was evaluated using the modified Frankel scale. According to this scale, 3 patients showed three grade improvements, 2 patients showed two grade improvements, and 1 patient showed one grade improvement in the modified Ohtsuka group. Three patients in the modified Ohtsuka group could walk without any support at the final follow-up.

CONCLUSIONS

The present study clearly indicated that the surgical outcomes of the authors’ modified Ohtsuka procedure were significantly better than those of PDF for patients who could not walk preoperatively.

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Toshimi Aizawa, Toshimitsu Eto, Ko Hashimoto, Haruo Kanno, Eiji Itoi, and Hiroshi Ozawa

OBJECTIVE

Thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) remains one of the most difficult-to-treat disorders for spine surgeons. In Japan, approximately 75% of patients with this condition are treated using posterior decompression with instrumented spinal fusion (PDF). In contrast, anterior decompression is the most effective method for relieving spinal cord compression. The authors treated nonambulatory patients with thoracic OPLL by either PDF or by their technique using anterior decompression through a posterior approach. In this study the surgical results of these procedures are compared.

METHODS

This was a retrospective case series. From 2008 to 2018, 9 patients with thoracic OPLL who could not walk preoperatively were treated surgically. Three patients were treated by PDF (the PDF group) and 6 patients were treated by anterior decompression through a posterior approach (the modified Ohtsuka group). The degree of surgical invasion and the neurological conditions of the patients were assessed.

RESULTS

The PDF group had a shorter operative duration (mean 477 ± 122 vs 569 ± 92 minutes) and less intraoperative blood loss (mean 613 ± 380 vs 1180 ± 614 ml), although the differences were not statistically significant. The preoperative Japanese Orthopaedic Association (JOA) score was almost identical between the two groups; however, the latest JOA score and the recovery rate were significantly better in the modified Ohtsuka group than in the PDF group (8.8 ± 1.5 vs 5.0 ± 1.7 and 71.3% ± 23.7% vs 28.3% ± 5.7%, respectively). The walking ability was evaluated using the modified Frankel scale. According to this scale, 3 patients showed three grade improvements, 2 patients showed two grade improvements, and 1 patient showed one grade improvement in the modified Ohtsuka group. Three patients in the modified Ohtsuka group could walk without any support at the final follow-up.

CONCLUSIONS

The present study clearly indicated that the surgical outcomes of the authors’ modified Ohtsuka procedure were significantly better than those of PDF for patients who could not walk preoperatively.

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Kenichiro Yahata, Haruo Kanno, Hiroshi Ozawa, Seiji Yamaya, Satoshi Tateda, Kenta Ito, Hiroaki Shimokawa, and Eiji Itoi

OBJECTIVE

Extracorporeal shock wave therapy (ESWT) is widely used to treat various human diseases. Low-energy ESWT increases expression of vascular endothelial growth factor (VEGF) in cultured endothelial cells. The VEGF stimulates not only endothelial cells to promote angiogenesis but also neural cells to induce neuroprotective effects. A previous study by these authors demonstrated that low-energy ESWT promoted expression of VEGF in damaged neural tissue and improved locomotor function after spinal cord injury (SCI). However, the neuroprotective mechanisms in the injured spinal cord produced by low-energy ESWT are still unknown. In the present study, the authors investigated the cell specificity of VEGF expression in injured spinal cords and angiogenesis induced by low-energy ESWT. They also examined the neuroprotective effects of low-energy ESWT on cell death, axonal damage, and white matter sparing as well as the therapeutic effect for improvement of sensory function following SCI.

METHODS

Adult female Sprague-Dawley rats were divided into the SCI group (SCI only) and SCI-SW group (low-energy ESWT applied after SCI). Thoracic SCI was produced using a New York University Impactor. Low-energy ESWT was applied to the injured spinal cord 3 times a week for 3 weeks after SCI. Locomotor function was evaluated using the Basso, Beattie, and Bresnahan open-field locomotor score for 42 days after SCI. Mechanical and thermal allodynia in the hindpaw were evaluated for 42 days. Double staining for VEGF and various cell-type markers (NeuN, GFAP, and Olig2) was performed at Day 7; TUNEL staining was also performed at Day 7. Immunohistochemical staining for CD31, α-SMA, and 5-HT was performed on spinal cord sections taken 42 days after SCI. Luxol fast blue staining was performed at Day 42.

RESULTS

Low-energy ESWT significantly improved not only locomotion but also mechanical and thermal allodynia following SCI. In the double staining, expression of VEGF was observed in NeuN-, GFAP-, and Olig2-labeled cells. Low-energy ESWT significantly promoted CD31 and α-SMA expressions in the injured spinal cords. In addition, low-energy ESWT significantly reduced the TUNEL-positive cells in the injured spinal cords. Furthermore, the immunodensity of 5-HT–positive axons was significantly higher in the animals treated by low-energy ESWT. The areas of spared white matter were obviously larger in the SCI-SW group than in the SCI group, as indicated by Luxol fast blue staining.

CONCLUSIONS

The results of this study suggested that low-energy ESWT promotes VEGF expression in various neural cells and enhances angiogenesis in damaged neural tissue after SCI. Furthermore, the neuroprotective effect of VEGF induced by low-energy ESWT can suppress cell death and axonal damage and consequently improve locomotor and sensory functions after SCI. Thus, low-energy ESWT can be a novel therapeutic strategy for treatment of SCI.

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Seiji Yamaya, Hiroshi Ozawa, Haruo Kanno, Koshi N. Kishimoto, Akira Sekiguchi, Satoshi Tateda, Kenichiro Yahata, Kenta Ito, Hiroaki Shimokawa, and Eiji Itoi

Object

Extracorporeal shock wave therapy (ESWT) is widely used for the clinical treatment of various human diseases. Recent studies have demonstrated that low-energy ESWT upregulates the expression of vascular endothelial growth factor (VEGF) and promotes angiogenesis and functional recovery in myocardial infarction and peripheral artery disease. Many previous reports suggested that VEGF produces a neuroprotective effect to reduce secondary neural tissue damage after spinal cord injury (SCI). The purpose of the present study was to investigate whether lowenergy ESWT promotes VEGF expression and neuroprotection and improves locomotor recovery after SCI.

Methods

Sixty adult female Sprague-Dawley rats were randomly divided into 4 groups: sham group (laminectomy only), sham-SW group (low-energy ESWT applied after laminectomy), SCI group (SCI only), and SCI-SW group (low-energy ESWT applied after SCI). Thoracic spinal cord contusion injury was inflicted using an impactor. Low-energy ESWT was applied to the injured spinal cord 3 times a week for 3 weeks. Locomotor function was evaluated using the Basso, Beattie, and Bresnahan (BBB) Scale (open field locomotor score) at different time points over 42 days after SCI. Hematoxylin and eosin staining was performed to assess neural tissue damage in the spinal cord. Neuronal loss was investigated by immunostaining for NeuN. The mRNA expressions of VEGF and its receptor, Flt-1, in the spinal cord were assessed using real-time polymerase chain reaction. Immunostaining for VEGF was performed to evaluate VEGF protein expression in the spinal cord.

Results

In both the sham and sham-SW groups, no animals showed locomotor impairment on BBB scoring. Histological analysis of H & E and NeuN stainings in the sham-SW group confirmed that no neural tissue damage was induced by the low-energy ESWT. Importantly, animals in the SCI-SW group demonstrated significantly better locomotor improvement than those in the SCI group at 7, 35, and 42 days after injury (p < 0.05). The number of NeuN-positive cells in the SCI-SW group was significantly higher than that in the SCI group at 42 days after injury (p < 0.05). In addition, mRNA expressions of VEGF and Flt-1 were significantly increased in the SCI-SW group compared with the SCI group at 7 days after injury (p < 0.05). The expression of VEGF protein in the SCI-SW group was significantly higher than that in the SCI group at 7 days (p < 0.01).

Conclusions

The present study showed that low-energy ESWT significantly increased expressions of VEGF and Flt-1 in the spinal cord without any detrimental effect. Furthermore, it significantly reduced neuronal loss in damaged neural tissue and improved locomotor function after SCI. These results suggested that low-energy ESWT enhances the neuroprotective effect of VEGF in reducing secondary injury and leads to better locomotor recovery following SCI. This study provides the first evidence that low-energy ESWT can be a safe and promising therapeutic strategy for SCI.

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Hiroshi Ozawa, Takashi Kusakabe, Toshimi Aizawa, Takeshi Nakamura, Yushin Ishii, and Eiji Itoi

The authors describe 2 patients with C-2 nerve root tumors in whom the lesions were located bilaterally in the lateral portions of the C1–2 interlaminar space and compressed the spinal cord when the atlantoaxial joint was rotated.

The patients were adult men with neurofibromatosis. Each presented with clumsiness of both hands and motor weakness of the extremities accompanied by spastic gait. Magnetic resonance imaging of the cervical spine performed with the neck in the neutral position showed tumors at the bilateral lateral portion of the C1–2 interlaminar space without direct compression of the spinal cord. The spinal cord exhibited an I-shaped deformity at the same level as the tumors in one case and a trapezoidal deformity at the same level as the tumors in the other case. Computed tomography myelography and MRI on rotation of the cervical spine revealed bilateral intracanal protrusion of the tumors compressing the spinal cord from the lateral side. The tumors were successfully excised and occipitocervical fusion was performed.

The tumors were pushed out into the spinal canal from the bilateral lateral portion of the interlaminar spaces due to rotation of the atlantoaxial joint. This was caused by a combination of posteromedial displacement of the lateral mass on the rotational side of the atlas and narrowing of the lateral portion of the interlaminar space on the contralateral side due to the coupling motion of the lateral bending and extension of the atlas. The spinal cord underwent compression from both lateral sides in a one-way rotation. Without sustained spinal cord compression, intermittent long-term dynamic spinal cord compression from both lateral sides should induce a pathognomonic spinal cord deformity and the onset of paralysis. To the authors' knowledge, there have been no reports of the present conditions—that is, the bilateral protrusion of tumors from the bilateral lateral portion of the C1–2 interlaminar spaces into the spinal canal due to atlantoaxial rotation.

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Haruo Kanno, Toshimi Aizawa, Hiroshi Ozawa, Takeshi Hoshikawa, Eiji Itoi, and Shoichi Kokubun

The authors report a rare case of tethered cord syndrome with low-placed conus medullaris complicated by a vertebral fracture that was successfully treated by a spine-shortening vertebral osteotomy. The patient was a 57-year-old woman whose neurological condition worsened after a T-12 vertebral fracture because a fracture fragment and the associated local kyphotic deformity directly compressed the tethered spinal cord. An osteotomy of the T-12 vertebra was performed in order to correct the kyphosis, remove the fracture fragment, and reduce the tension on the spinal cord. Postoperative radiographs showed the spine to be shortened by 22 mm, and the kyphosis between T-11 and L-1 improved from 23° to 0°. Two years after the surgery, the patient's neurological symptoms were resolved. The bone union was complete with no loss of correction.

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Toshimi Aizawa, Tetsuro Sato, Hiroshi Ozawa, Naoki Morozumi, Fujio Matsumoto, Hirotoshi Sasaki, Takeshi Hoshikawa, Chikashi Kawahara, Shoichi Kokubun, and Eiji Itoi

Object

The increased kyphosis after thoracic laminectomy in adult patients was retrospectively evaluated and various factors affecting this spinal deformity were analyzed.

Methods

The authors conducted a retrospective study of 58 cases in which laminectomy was performed and more than half of the facet joints were left intact. The study group included 44 men (mean age 59 years) and 14 women (mean age 61 years) with thoracic myelopathy due to ossifications of the ligamentum flavum and/or the posterior longitudinal ligament or due to posterior bone spurs. Patients were followed up for a minimum of 2 years. Their neurological condition was evaluated using the Japanese Orthopaedic Association (JOA) scale (a full score is 11), and the magnitude of local kyphosis in the laminectomized area was determined using the Cobb angle method.

Results

The mean preoperative JOA score was 5.4; the mean postoperative score was 8.3. No relationship was found between postoperative JOA score and increased kyphotic angle. The mean preoperative kyphotic angle was 7.0°. The mean postoperative kyphotic angle was 10.8°. Thus local kyphosis in the treated area increased by only 3.8°. The mean increase in kyphosis per spinal segment, calculated by dividing the kyphotic angle of the surgically decompressed area by the number of resected laminae, was 1.9°. Female patients with ≥ 3-level laminectomies showed a significant increase of kyphosis in both the laminectomized area and each spinal segment.

Conclusions

The increase in kyphosis after thoracic laminectomy is not large and thus spinal fusion is usually not necessary. In cases involving female patients who undergo long-segment laminectomies, however, careful radiographic follow-up is recommended.

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Toshimi Aizawa, Tetsuro Sato, Hirotoshi Sasaki, Fujio Matsumoto, Naoki Morozumi, Takashi Kusakabe, Eiji Itoi, and Shoichi Kokubun

Object

Thoracic myelopathy is uncommon compared with cervical myelopathy. In this study, data obtained in patients with thoracic myelopathy caused by degenerative processes of the spine were retrospectively analyzed to clarify the surgical outcomes and to examine the various factors affecting the postoperative improvement.

Methods

Between 1988 and 2002, 132 patients with thoracic myelopathy underwent surgery and a minimum 2-year observation period. Clinical data were collected from medical and operative records, and sagittal alignment of the spine was measured on radiographs. The patients were evaluated pre- and postoperatively using the modified Japanese Orthopaedic Association (JOA) scale (maximum score 11). The relationships among various factors affecting the preoperative severity of myelopathy and postoperative improvement were also examined.

Results

The population consisted of 97 men (mean age at surgery was 58 years) and 35 women (mean age at surgery 62 years). Myelopathy was caused by ossification of the ligamentum flavum (OLF) in 73 patients, ossification of the posterior longitudinal ligament (OPLL) in 21, combined OLF–OPLL in 10, intervertebral disc herniation (IDH) in 15, posterior bone spur in 11, and OLF with IDH or posterior bone spur in one patient each. The surgical outcome was relatively good: a mean preoperative JOA score of 5.3 improved to a mean score of 7.8 at the last follow-up, 50 months on average after surgery. Thoracic myelopathy caused by OPLL, however, was associated with lower postoperative scores and recovery rates. In more than half of the patients the authors documented an increase of kyphosis of less than 2°.

Conclusions

Patients with a shorter preoperative duration of symptoms and milder myelopathy experienced significantly better postoperative neurological conditions, which indicated that those who present earlier with fewer disabilities should be recommended to undergo surgery in time, although the surgical treatment for OPLL still involves many problems.

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Yoichi Shimada, Yuji Kasukawa, Naohisa Miyakoshi, Michio Hongo, Shigeru Ando, and Eiji Itoi

✓ The thoracic spine is stabilized in the anteroposterior direction by the rib cage and the facet joints. Spondylolisthesis of the thoracic spine is less common than that of the lumbar spine. The authors describe a rare case of thoracic spondylolisthesis in which the patient suffered back pain and myelopathy. The patient was a 44-year-old woman. Plain radiography revealed Grade I T11–12 spondylolisthesis. The pedicle–facet joint angle at T-11 was 118°, greater than that of T-10 or T-12. Postmyelography computerized tomography scanning revealed posterior compression of the dural sac as well as enlargement of and degenerative changes in the facet joint at T-11. Magnetic resonance imaging showed anterior and posterior compression of the spinal cord at the level of the spondylolisthesis. To achieve posterior T10–12 decompression, the surgeons performed a laminectomy and posterolateral fusion in which a pedicle screw fixation system was placed. The patient’s back pain disappeared immediately after the operation. The authors conclude that the enlargement of the pedicle–facet joint angle and the degenerative changes of the facet joint caused the thoracolumbar spondylolisthesis.

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Yoshinori Ishikawa, Yoichi Shimada, Naohisa Miyakoshi, Tetsuya Suzuki, Michio Hongo, Yuji Kasukawa, Kyoji Okada, and Eiji Itoi

Object

Idiopathic symptomatic spinal epidural lipomatosis (SEL) is a rare condition, and few reports have discussed diagnostic imaging criteria. To evaluate factors relating to its clinical symptoms, correlations between clinical features and the presence of spinal epidural fat were investigated, and the literature concerning idiopathic SEL was reviewed.

Methods

Morphological gradings of epidural fat were evaluated in seven patients with idiopathic SEL by using magnetic resonance (MR) imaging. In addition, body mass index (BMI), the number of involved vertebral levels, grade, and preoperative Japanese Orthopaedic Association (JOA) score were analyzed. Surgery resulted in symptomatic relief, with a mean JOA score recovery rate of 67.4%. Grading of epidural fat tended to display a slight negative correlation with preoperative JOA score, whereas a strong significant positive correlation was found between the number of involved vertebral levels and BMI.

Conclusions

The number of involved vertebral levels and obesity are strongly correlated, whereas severity of dural compression is not always significantly associated with neurological complications. These results indicate that epidural fat of the lumbar spine contributes to neurological deficits. In addition, weight-reduction therapy appears to decrease the number of vertebral levels involved. Magnetic resonance imaging–based grading is helpful for the diagnosis and evaluation of idiopathic lumbar SEL. Moreover, symptoms and neurological findings are important for determining the surgical approach.