STUDY DESIGN: Prospective comparative study. PURPOSE: To compare the incidence and severity of adverse reactions associated with myelography performed in outpatients vs. in inpatients and report the safety and usefulness of outpatient myelography in Japanese patients. OVERVIEW OF LITERATURE: Myelography is normally performed as an inpatient procedure in most hospitals in Japan. No studies have reported the usefulness and adverse effects of outpatient myelography in Japanese patients. METHODS: We performed 221 myelography procedures. Eighty-five of the 221 patients underwent outpatient myelography using our new protocol. The incidence and severity of adverse reactions were compared with the other 136 patients, who underwent conventional inpatient myelography. We further compared the cost of outpatient and inpatient myelography. RESULTS: The overall rate of adverse effects was 9.4% in outpatients, as compared with 7.4% in inpatients. Overall, 1.2% of outpatients and 0.74% inpatients experienced "severe" adverse effects (requiring hospitalization). There were no significant differences between the 2 groups in either the overall rate of adverse effects or the rate of "severe" adverse effects. Moreover, the average outpatient procedure cost was only one-third to one-half that of the inpatient procedure. CONCLUSIONS: This was the first study to address the safety and usefulness of outpatient myelography in Japanese patients. If selected according to proper inclusion criteria for outpatient procedure, no significant differences were observed in the adverse effects between inpatients and outpatients. The outpatient procedure is more economical and has the added benefit of being more convenient and time-efficient for the patient.
Asian Continental Ancestry Group ; Health Care Costs ; Humans ; Incidence ; Inpatients* ; Japan* ; Myelography* ; Outpatients* ; Prospective Studies*

We describe successful vertebrectomy from a posterior approach using a computed tomography (CT)-based navigation system (O-arm) in a 53-year-old man with adenocarcinoma of the posterior apex of the right lung with invasion of the adjacent rib, thoracic wall, and T2 and T3 vertebral bodies. En bloc partial vertebrectomy for lung cancer adjacent to the thoracic spine was planned using O-arm. First, laminectomy was performed from right T2 to T3, and pedicles and transverse processes of T2 to T3 were resected. O-arm was used to confirm the location of the cutting edge in the T2 to 3 right vertebral internal body, and osteotomy to the anterior cortex was performed with a chisel. Next, the patient was placed in a left decubitus position. The surgical specimen was extracted en bloc. This case shows that O-arm can be used reliably and easily in vertebrectomy from a posterior approach and can facilitate en bloc resection.
Adenocarcinoma ; Humans ; Laminectomy ; Lung Neoplasms* ; Lung* ; Middle Aged ; Osteotomy ; Ribs ; Spine* ; Thoracic Wall

STUDY DESIGN: Animal study. PURPOSE: To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. OVERVIEW OF LITERATURE: Little is known about correlation palesis and amplitude of spinal cord monitoring. METHODS: After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morphology change of the CMAP wave and locomotor scale were evaluated for one month. RESULTS: Four different types of wave morphology changes were observed: no change, amplitude decrease only, morphology change only, and amplitude and morphology change. Amplitude and morphology changed simultaneously and significantly as the injury force increased (p<0.05) Locomotor scale in the amplitude and morphology group worsened more than the other groups. CONCLUSIONS: Amplitude and morphology change of the CMAP wave exists and could be the key of the alarm point in CMAP.
Action Potentials* ; Animals* ; Contusions ; Gravitation ; Laminectomy ; Models, Animal* ; Spinal Cord

Thoracic ossification of the ligamentum flavum (T-OLF) is a relatively rare spinal disorder that generally requires surgical intervention, due to its progressive nature and the poor response to conservative therapy. The prevalence of OLF has been reported at 3.8%-26%, which is similar to that of cervical ossification of the posterior longitudinal ligament (OPLL). The progression of OPLL after cervical laminoplasty for the treatment of OPLL is often shown in long-term follow-up. However, there have been no reports on the progression of OLF following surgery. We report a case of thoracic myelopathy secondary to the progressive relapse of OLF following laminectomy.
Follow-Up Studies ; Laminectomy ; Ligamentum Flavum* ; Longitudinal Ligaments ; Prevalence ; Recurrence* ; Spinal Cord Diseases

Struma ovarii is a rare tumor that is defined as an ovarian teratoma with a thyroid tissue component exceeding 50%. Most of these tumors are benign, with malignant struma ovarii occurring in <1% of patients. Here, we describe the case of a 49-year-old female patient with malignant struma ovarii who developed thoracic spine metastasis. She had undergone an oophorectomy and was diagnosed with struma ovarii 10 years previously. She had remained recurrence-free thereafter. At 49 years of age, she developed low back pain and was admitted to our hospital for evaluation of a spinal tumor at the Th7 level. An emergency bone biopsy led to a diagnosis of metastasis from malignant struma ovarii. External beam radiotherapy inhibited further tumor growth and there was no resulting muscle weakness. This is the first report of spinal metastasis occurring 10 years after resection of struma ovarii, indicating the need for long-term follow-up.
Biopsy ; Diagnosis ; Emergencies ; Female ; Humans ; Low Back Pain ; Middle Aged ; Muscle Weakness ; Neoplasm Metastasis* ; Ovariectomy ; Radiotherapy ; Recurrence ; Spinal Neoplasms ; Spine ; Struma Ovarii* ; Teratoma ; Thyroid Gland

STUDY DESIGN: Retrospective case–control study. PURPOSE: To compare surgical invasiveness and radiological outcomes between posterior lumbar interbody fusion (PLIF) and lateral lumbar interbody fusion (LLIF) for degenerative lumbar kyphosis. OVERVIEW OF LITERATURE: LLIF is a minimally invasive interbody fusion technique; however, few reports compared the clinical outcomes of conventional PLIF and LLIF for degenerative lumbar kyphosis. METHODS: Radiographic data for patients who have undergone lumbar interbody fusion (≥3 levels) using PLIF or LLIF for degenerative lumbar kyphosis (lumbar lordosis [LL] <20°) were retrospectively examined. The following radiographic parameters were retrospectively evaluated preoperatively and 2 years postoperatively: segmental lordotic angle, LL, pelvic tilt (PT), pelvic incidence (PI), C7 sagittal vertical axis, and T1 pelvic angle. RESULTS: Nineteen consecutive cases with PLIF and 27 cases with LLIF were included. There were no significant differences in patients' backgrounds or preoperative radiographic parameters between the PLIF and the LLIF groups. The mean fusion level was 5.5±2.5 levels and 5.8±2.5 levels in the PLIF and LLIF groups, respectively (p=0.69). Although there was no significant difference in surgical times (p=0.58), the estimated blood loss was significantly greater in the PLIF group (p<0.001). Two years postoperatively, comparing the PLIF and LLIF groups, the segmental lordotic angle achieved (7.4°±7.6° and 10.6°±9.4°, respectively; p=0.03), LL (27.8°±13.9° and 39.2°±12.7°, respectively; p=0.006), PI–LL (19.8°±14.8° and 3.1°±17.5°, respectively; p=0.002), and PT (22.6°±7.1° and 14.2°±13.9°, respectively; p=0.02) were significantly better in the LLIF group. CONCLUSIONS: LLIF provided significantly better sagittal alignment restoration in the context of degenerative lumbar kyphosis, with less blood loss.
Animals ; Humans ; Incidence ; Kyphosis ; Lordosis ; Minimally Invasive Surgical Procedures ; Operative Time ; Retrospective Studies

STUDY DESIGN: Prospective cohort study. PURPOSE: This study aimed to identify risk factors for unplanned second-stage decompression for postoperative neurological deficit after indirect decompression using lateral lumbar interbody fusion (LLIF) with posterior fixation. OVERVIEW OF LITERATURE: Indirect lumbar decompression with LLIF has been used as a minimally invasive alternative to direct decompression to treat degenerative lumbar diseases requiring neural decompression. However, evidence on the prevalence of neurological deficits caused by spinal canal stenosis after indirect decompression is limited. METHODS: This study included 158 patients (mean age, 71.13±7.98 years; male/female ratio, 67/91) who underwent indirect decompression with LLIF and posterior fixation. Indirect decompression was performed at 271 levels (mean level, 1.71±0.97). Logistic regression analysis was used to identify the risk factors for postoperative neurological deficits. The variables included were age, sex, body mass index, presence of primary diseases, diabetes mellitus, preoperative motor deficit, levels operated on, preoperative severity of lumbar stenosis, and preoperative Japanese Orthopedic Association (JOA) score. RESULTS: Postoperative neurological deficit due to spinal canal stenosis occurred in three patients (1.9%). Spinal stenosis due to hemodialysis (p<0.001), ligament ossification (p<0.001), presence of preoperative motor paralysis (p<0.001), low JOA score (p=0.004), and severe canal stenosis (p=0.02) were significantly more frequent in the paralysis group. CONCLUSIONS: Severe preoperative canal stenosis and neurological deficit were identified as risk factors for postoperative neurological deterioration caused by spinal canal stenosis. Additionally, uncommon diseases, such as spinal stenosis due to hemodialysis and ligament ossification, increased the risk of postoperative neurological deficit; therefore, in such cases, indirect decompression is contraindicated.
Asian Continental Ancestry Group ; Body Mass Index ; Cohort Studies ; Constriction, Pathologic ; Decompression ; Diabetes Mellitus ; Humans ; Ligaments ; Logistic Models ; Orthopedics ; Paralysis ; Prevalence ; Prospective Studies ; Renal Dialysis ; Risk Factors ; Spinal Canal ; Spinal Stenosis

STUDY DESIGN: Prospective cohort study. PURPOSE: To identify factors that affect sagittal alignment correction in lateral lumbar interbody fusion (LIF) surgery for adult spinal deformity (ASD) and to investigate the degree of correction in each condition. OVERVIEW OF LITERATURE: LIF is a useful procedure for ASD, but the degree of correction can be affected by posterior osteotomy, intraoperative endplate injury, or anterior longitudinal ligament (ALL) rupture. METHODS: Radiographical data for 30 patients who underwent LIF for ASD were examined prospectively. All underwent two-stage surgery (LIF followed by posterior fixation). Radiographical parameters were measured preoperatively, after LIF, and after posterior fixation; these included the segmental lordotic angle, lumbar lordosis (LL), and other sagittal alignment factors. RESULTS: LL was corrected from 16.5°±16.7° preoperatively to 33.4°±13.8° after LIF (p<0.001) and then to 52.1°±7.9° following posterior fixation (p<0.001). At levels where Schwab grade 2 osteotomy was performed, the acquired segmental lordotic angles from the preoperative value to after posterior fixation and from after LIF to after posterior fixation were 19.5°±9.2° and 9.9°±3.9°, respectively. On average, 12.4° more was added than in cases without osteotomy. Endplate injury was identified at 21 levels (19.4%) after LIF, with a mean loss of 3.4° in the acquired segmental lordotic angle (5.3°±8.4° and 1.9°±5.9° without and with endplate injury, respectively). ALL rupture was identified at seven levels (6.5%), and on average 19.3° more was added in these cases between the preoperative and postoperative values than in cases without ALL rupture. CONCLUSIONS: LIF provides adequate sagittal alignment restoration for ASD, but the degree of correction is affected by grade 2 osteotomy, intraoperative endplate injury, and ALL rupture.

STUDY DESIGN: Retrospective case-control study.PURPOSE: We aimed to compare radiologic outcomes between posterior (PLIF) and lateral lumbar interbody fusion (LLIF) in short-level spinal fusion surgeries.OVERVIEW OF LITERATURE: Although LLIF enables surgeons to insert large lordotic cages, it is unknown whether LLIF more effectively corrects local and global sagittal alignments compared with PLIF in short-level spinal fusion surgeries.METHODS: Radiographic data acquired from patients with lumbar interbody fusion (≤3 levels) using PLIF or LLIF for degenerative lumbar diseases were analyzed. The following radiographic parameters were evaluated preoperatively and at 2 years postoperatively: segmental lordotic angle, disk height, lumbar lordosis (LL), pelvic tilt (PT), C7 sagittal vertical axis, and thoracic kyphosis (TK).RESULTS: In total, 144 patients with PLIF (193 fused levels) and 101 with LLIF (159 fused levels) were included. Patients’ backgrounds and preoperative radiographic parameters for any level of fusion did not differ significantly between PLIF and LLIF procedures. The LLIF group exhibited significantly greater changes at 1-level fusion compared to the PLIF group in the parameters of segmental lordotic angle (5.1°±5.8° vs. 2.1°±5.0°, p<0.001), disk height (4.2±2.3 mm vs. 2.2±2.0 mm, p<0.001), LL (7.8°±7.6° vs. 3.9°±8.6°, p=0.004), and PI–LL (−6.9°±6.8° vs. −3.6°±10.1°, p=0.03). While, a similar trend was observed regarding 2-level fusion, significantly greater changes were only observed in LL (12.1°±11.1° vs. 4.2°±9.1°, p=0.047) and PI–LL (−11.2°±11.3° vs. −3.0°±9.3°, p=0.043), PT (−6.4°±4.9° vs. −2.5°±5.3°, p=0.049) and TK (7.8°±11.8° vs. −0.3°±9.7°, p=0.047) in the LLIF group at 3-level fusion.CONCLUSIONS: LLIF provides significantly better local sagittal alignment than PLIF in 1- or 2-level fusion cases and improves spinopelvic alignment and local alignment for 3-level fusion cases. Thus, LLIF was demonstrated to be a useful lumbar interbody fusion technique, constituting a powerful tool for achieving sagittal realignment with minimal surgical invasiveness.
Animals ; Case-Control Studies ; Humans ; Kyphosis ; Lordosis ; Retrospective Studies ; Spinal Fusion ; Surgeons

Methods: This retrospective study included 35 patients (mean age, 72.8±8.0 years; male, 10; female, 25) who underwent lumbosacral fixation using SAI screws with at least 2 years of follow-up. SAI screw loosening and L5–S bony fusion were assessed using computed tomography. The period for which the screws appeared loose and the risk factors for SAI screw loosening were investigated 2 years after surgery. Results: A total of 70 SAI screws and 70 S1 pedicle screws were inserted. Loosening was observed 0.5, 1, and 2 years after surgery in 17 (24.3%), 35 (50.0%), and 35 (50.0%) SAI screws, respectively. Bony fusion rate at L5–S was significantly lower in patients with SAI screw loosening than in those without screw loosening (65.0% vs. 93.3%, p =0.048). The score for SAI screw contact with the iliac cortical bone and the bony fusion rate at L5–S were significantly lower in the loosening group than in the non-loosening group (1.8±0.5 vs. 2.2±0.3, p <0.001, respectively). Postoperative pelvic incidence–lumbar lordosis was significantly higher in the loosening group than in the non-loosening group (7.9°±15.4° vs. 0.5°±8.7°, p =0.02, respectively). Conclusions SAI screw loosening is closely correlated with pseudoarthrosis at L5–S. Appropriate screw insertion and optimal lumbar lordosis restoration are important to prevent postoperative complications related to SAI screws.