Tadayoshi Kobayashi

STUDY DESIGN: A new surgical strategy for treatment of patients with spinal metastases was designed, and 61 patients were treated based on this strategy. OBJECTIVES: To propose a new surgical strategy for the treatment of patients with spinal metastases. SUMMARY OF BACKGROUND DATA: A preoperative score composed of six parameters has been proposed by Tokuhashi et al for the prognostic assessment of patients with metastases to the spine. Their scoring system was designed for deciding between excisional or palliative procedures. Recently, aggressive surgery, such as total en bloc spondylectomy for spinal metastases, has been advocated for selected patients. Surgical strategies should include various treatments ranging from wide or marginal excision to palliative treatment with hospice care. METHODS: Sixty-seven patients with spinal metastases who had been treated from 1987-1991 were reviewed, and prognostic factors were evaluated retrospectively (phase 1). A new scoring system for spinal metastases that was designed based on these data consists of three prognostic factors: 1) grade of malignancy (slow growth, 1 point; moderate growth, 2 points; rapid growth, 4 points), 2) visceral metastases (no metastasis, 0 points; treatable, 2 points: untreatable, 4 points), and 3) bone metastases (solitary or isolated, 1 point; multiple, 2 points). These three factors were added together to give a prognostic score between 2-10. The treatment goal for each patient was set according to this prognostic score. The strategy for each patient was decided along with the treatment goal: a prognostic score of 2-3 points suggested a wide or marginal excision for long-term local control; 4-5 points indicated marginal or intralesional excision for middle-term local control; 6-7 points justified palliative surgery for short-term palliation; and 8-10 points indicated nonoperative supportive care. Sixty-one patients were treated prospectively according to this surgical strategy between 1993-1996 (phase 2). The extent of the spinal metastases was stratified using the surgical classification of spinal tumors, and technically appropriate and feasible surgery was performed, such as en bloc spondylectomy, piecemeal thorough excision, curettage, or palliative surgery. RESULTS: The mean survival time of the 28 patients treated with wide or marginal excision was 38.2 months (26 had successful local control). The mean survival time of the 13 patients treated with intralesional excision was 21.5 months (nine had successful local control). The mean survival time of the 11 patients treated with palliative surgery and stabilization was 10.1 months (eight had successful local control). The mean survival time of the patients with terminal care was 5.3 months. CONCLUSIONS: A new surgical strategy for spinal metastases based on the prognostic scoring system is proposed. This strategy provides appropriate guidelines for treatment in all patients with spinal metastases.

STUDY DESIGN: Seven patients with angular kyphotic deformity of the thoracic or thoracolumbar spine were treated by closing-opening wedge osteotomy using a single posterior approach. OBJECTIVES: To examine the safety and efficacy of closing-opening wedge osteotomy for angular kyphosis. SUMMARY OF BACKGROUND DATA: Correction osteotomy of severe kyphosis is a challenging operation. A two-stage operation has been commonly used: anterior release and decompression followed by posterior correction and fusion. METHODS: Seven patients with angular kyphosis were treated. The apex level of kyphosis was T5 in one patient, T11 in one, and T12 in five. There was old fracture in five patients, congenital deformity in one, and neurofibromatosis in one. The first 30-35 degrees of kyphosis are corrected using the closing wedge technique with the hinge of the anterior longitudinal ligament after veretebrectomy and circumspinal decompression of the spinal cord. Then the hinge is moved posteriorly to the spinal cord and the remainder of the requisit angle of osteotomy is corrected using the opening-wedge technique (closing-opening wedge osteotomy). Spinal curvature is stabilized using posterior instrumentation and graft. RESULTS: Localized kyphosis was reduced from an average of 67 degrees to 18 degrees at 2.2 to 7.5 years' follow-up. Sagittal alignment from T1 to the sacrum became more physiologic than before. There were no neurologic complications. Bony fusion was achieved in all patients, and there was no correction loss. CONCLUSIONS: Satisfactory correction is safely performed by closing-opening wedge osteotomy with a direct visualization of the circumferentially decompressed spinal cord. Although the performance is technically laborious, it offers good correction without jeopardizing the integrity of the spinal cord.

STUDY DESIGN: Morphometric changes of the spinal cord and influence on spinal cord-evoked potentials and spinal cord blood flow and postoperative function of hind limbs were studied in various degrees of acute spinal column shortening in dogs. OBJECTIVES: To study the morphometric and physiologic effects of acute spinal column shortening on the spinal cord. SUMMARY OF BACKGROUND DATA: The technique of acute spinal column shortening is sometimes applied for correction of spinal deformity, total en bloc spondylectomy operation, or other diseases. However, safe limits and physiologic effects of acute spinal column shortening have not yet been described. METHODS: Total spondylectomy of T13 was performed in dogs after spinal instrumentation placed 2 levels above and 2 levels below the spondylectomy level. Spinal column was gradually shortened until the lower endplate of T12 contacted the L1 upper endplate (maximum of 20 mm). When any morphologic change of the dural sac or the spinal cord was observed, the length of shortening was measured. Spinal cord-evoked potentials were recorded on the exposed dura mater following epidural stimulation at the C7 level in 8 dogs. Spinal cord blood flow was measured during shortening in 6 dogs. Hindlimb function was evaluated 2 weeks after operation in 10 dogs. RESULTS: No morphometric changes occurred in the dural sac and the spinal cord until shortening of 7.2 +/- 1.7 mm (n = 6). From 7.2 +/- 1.7 to 12.5 +/- 1.1 mm shortening, the dural sac was deformed, whereas the spinal cord maintained its shape. Shortening more than 12.5 +/- 1.1 mm buckled the dural sac, and the spinal cord kinked itself and was compressed by the buckled dura in its concave side (n = 6). No changes could be detected in spinal cord-evoked potentials in 5 or 10 mm of shortening. Spinal cord-evoked potential changes were recorded in the 2 of 6 dogs with 15 mm of shortening. At 20 mm of shortening, spinal cord-evoked potential abnormality was observed in 4 of 6 dogs. At shortening of 5, 10, 15, and 20 mm, spinal cord blood flow was 146 +/- 10%, 160 +/- 21%, 102 +/- 17%, and 93 +/- 7% of the control (29.2 +/- 7.9 mL/100 g/min, n = 6), respectively. All 3 dogs with 10 mm ofshortening had normal hindlimb function 2 weeks after operation. One of the 3 dogs with 15 mm of shortening had paraparesis. Three of the 4 dogs with 20 mm of shortening had also paraparesis after operation. CONCLUSIONS: Acute spinal column shortening can be characterized into 3 phases. Phase 1, safe range: occurred during shortening within one-third of the vertebral segment and is characterized by no deformity of the dural sac or the spinal cord. Phase 2, warning range: occurred during spinal shortening between one-third and two-thirds of the vertebral segment and is characterized by shrinking and buckling of the dural sac and no deformity of the spinal cord. Phase 3, dangerous range: occurred after shortening in excess of two-thirds of the vertebral segment and is characterized by spinal cord deformity and compression by the buckled dura. Spinal shortening within the safe range increases spinal cord blood flow.

BACKGROUND: The recurrence of lumbar disk herniation (LDH) is a major problem in the treatment of LDH. The purpose of this study was to investigate the risk factors for recurrent LDH. METHODS: Between April 2005 and March 2008, 298 patients with LDH, who underwent surgical treatment, were enrolled in this study. The patients were divided into a nonrecurrent group (N group) and a recurrent group (R group). We compared their clinical parameters including age, sex, body mass index, smoking, alcohol, sports activity, occupational lifting, and occupational driving. The relationships between the variables and recurrent LDH were evaluated by univariate analysis and multiple logistic regression analysis. RESULTS: The N group had 266 patients (89.3%) and the R group had 32 patients (10.7%). Univariate analysis showed that current smoking (P<0.001) and occupational lifting (P=0.02) significantly correlated with recurrent LDH. Multivariate analysis showed that current smoking significantly related with recurrent LDH (OR, 3.47; 95% CI, 1.55-7.80; P=0.003). CONCLUSIONS: Our study suggests that smoking cessation and restraining from lifting may significantly decrease the incidence of recurrent LDH.

STUDY DESIGN: A prospective study of patients whose spinal cord tumors were managed surgically with a unique posterior method of removing and replacing the posterior spinal elements using T-saw ("recapping T-saw laminoplasty"). OBJECTIVES: To examine the safety and efficacy of the recapping T-saw laminoplasty technique for spinal canal surgery. SUMMARY OF BACKGROUND DATA: Laminectomy, laminoplasty, and/or laminotomy typically are used to approach intraspinal lesions. When removal and replacement of the posterior elements have been attempted, the effectiveness of the technique has been limited by the amount of bone sacrificed when using burrs or osteotomes. The authors thought to adapt a unique "threadwire saw" (T-saw) in these cases, because its use results in minimal bone loss. METHODS: Patients underwent recapping T-saw laminoplasty in the thoracic or lumbar spine for extirpation of spinal cord tumors. The T-saw was used for division of the posterior elements. After resection of the lesion, the excised laminae were replaced exactly in situ to their original anatomic position. The mean follow-up period was 47 months (range, 31-71 months). Patients were observed neurologically and radiologically. RESULTS: One to eight laminae were excised and replaced in 24 patients. Findings on computed tomography scans confirmed primary bony union in 23 patients by 6 months after surgery, and in one patient by 12 months after surgery. No complications such as postoperative spinal canal stenosis, facet arthrosis, or kyphosis were observed. CONCLUSIONS: Recapping laminoplasty afforded anatomic reconstruction of the vertebral arch after excision of spinal cord tumors. This procedure appears to warrant further evaluation as an alternative to wide laminectomies for exposure of intraspinal tumors.