Hiroki Hirabayashi

Clinical outcome and survival after palliative surgery for spinal metastases: palliative surgery in spinal metastases.

The authors sought to identify treatment‐related factors that influenced survival after surgical treatment for metastatic spinal tumors and to evaluate the relationship between survival and postoperative ambulation time as a factor related to quality of life.

Usefulness of white blood cell differential for early diagnosis of surgical wound infection following spinal instrumentation surgery.

Study Design. The white blood cell (WBC) count and WBC differential were measured prospectively in patients after spinal instrumentation surgery with or without surgical wound infection. Objectives. To investigate the usefulness of WBC differential for early diagnosis of surgical wound infection after spinal instrumentation surgery. Summary of Background Data. Renewed elevation of C-reactive protein (CRP) or WBC, gallium scan, and CRP/transthyretin mass concentration ratio were reported for early diagnosis of surgical wound infection. Methods. A total of 39 patients were enrolled in this study: 13 patients who developed wound infection within 2 weeks after spinal instrumentation surgery (infection group) and 26 patients who were comparable with those patients included in the infection group with regard to age, sex, and surgical techniques used (control group). The WBC count and WBC differential were determined before and after surgery. Results. In both groups, WBC and percentage and number of neutrophils showed nearly same change until postoperative 4 days (day 4). However, in the infection group, these parameters had increased after day 4. In both groups, the percentage and number of lymphocytes decreased to 10% or less and 1,000/&mgr;L or less on day 1, respectively. These lymphocyte parameters began to gradually normalize on day 4 and returned to the preoperative level 3 weeks after surgery in the control group. On the other hand, these parameters remained 10% or less and 1,000/&mgr;L or less until day 11 in the infection group. In patients with infection, the percentage and number of lymphocytes significantly decreased as early as on day 4. Conclusion. Lymphopenia represents immunodepression status, thus indicating the increased susceptibility to infection, which may lead to the development of postoperative infection. If lymphopenia is diagnosed as early as possible, surgical wound infection can be treated promptly without removing the instruments.

Preoperative CT examination for accurate and safe anterior spinal instrumentation surgery with endoscopic approach.

The purpose of this article is to introduce a new procedure for the surgical planning of thoracic anterior spinal instrumentation via endoscopy. For accurate and safe anterior screw insertion via the endoscopic approach, we devised a surgical plan based on the preoperative chest computed tomography (CT) findings obtained with radiographic markers. Using this method, we performed endoscopic thoracic spinal instrumentation surgery in 14 patients. Nine patients underwent anterior endoscopic correction and fusion of idiopathic scoliosis by Cotrel-Dubousset instrumentation, and five patients underwent anterior endoscopic spinal fixation with instrumentation. The accuracy of screw insertion was evaluated postoperatively by CT scanning. One interbody fusion cage and 53 screws were inserted in the 14 patients using endoscopy. Postoperative CT scans revealed that the screws were all accurately inserted without any neurologic complications. In conclusion, using this novel procedure for surgical planning based on CT findings obtained with radiographic markers, anterior screws can be inserted safely and accurately via an endoscopic approach.

Assessment of cervical myelopathy using transcranial magnetic stimulation and prediction of prognosis after laminoplasty

Study Design. This study investigated the clinical usefulness of motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation of the brain for cervical myelopathy patients. Objective. The purpose of this study was to determine the usefulness of MEPs for the assessment of the severity of myelopathy and prediction of the outcome of laminoplasty. Summary of Background Data. Magnetic stimulation has been widely used for examination of the descending excitatory motor pathways in the central nervous system, but little attention has been paid to cervical myelopathy. Methods. We measured the MEPs of 56 patients who underwent surgery for cervical myelopathy. The MEPs from the abductor pollicis brevis, abductor digiti minimi, tibialis anterior, and abductor hallucis muscle were evoked by transcranial magnetic brain stimulation. The latency from the anterior horn cell of the spinal cord to the hand or foot muscles was also measured, with the F-value [(F + M − 1)/2] calculated. This was followed by estimation of the central motor conduction time (CMCT). Severity of clinical disability was scored on the basis of symptoms according to a modified ADL scale for cervical myelopathy of the Japanese Orthopedic Association (JOA) score. Results. The average CMCT of the symptomatic side significantly correlated with the preoperative JOA score. The average CMCT of the symptomatic side significantly correlated with the 1-year postoperative JOA score. The average CMCT for patients with poor outcome was significantly longer than that for patients with good outcome. CMCT of 15 milliseconds or more in the upper extremities or that of 22 milliseconds or more in the lower extremities indicated poor prognosis. Conclusion. In patients with cervical myelopathy, the CMCT significantly correlated with the results of clinical assessment. These findings regarding the duration of CMCT may be useful parameters in spinal pathology for prediction of the outcome of surgical treatment.

Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability

Study Design A retrospective study. Purpose To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system. Overview of Literature We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerls procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion. Methods Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawats pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion. Results The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system. Conclusions It was demonstrated that the CT-based navigation system is an effective support device for Magerls procedure.

A neurofibromatosis type 1 patient with severe kyphoscoliosis and intrathoracic meningocele.

The patient presented with neurofibromatosis and a dystrophic kyphoscoliosis around the cervico-thoracic junction. When the patient was 59 years old, he started to suffer from dyspnea caused by an intrathoracic meningocele in the upper left thoracic cavity. A wide laminectomy from T2 to T5 was performed and the meningocele was resected. Although the dyspnoea disappeared postoperatively, the patient started to neurologically deteriorate. Laminectomy alone caused instability around the apex of the kyphosoliosis and spinal cord compression. Halo cast was applied and brought remarkable recovery of neurologic deficits. This result encouraged us to perform posterior fusion in situ from C3 to L2 with bone graft from the iliac crests and the Luque technique in conjunction with the Isola system. This resulted in the patient being able to walk again. The removal of the posterior element predisposes the patient to unstable postlaminectomy kyphosis and removes valuable bone stock required for posterior spinal fusion. For this reason, spinal fusion should have been conducted during surgery for the patients meningocele.

Long-term Results of Computer-assisted Posterior Occipitocervical Reconstruction

BACKGROUND Instability of the occipitocervical junction can present challenging surgical problems because of the unique anatomic and biomechanical characteristics of this region. The purpose of this study was to evaluate the long-term surgical results and usefulness of a computed tomography (CT)-based navigation system for the occipitocervical reconstruction. METHODS Twenty-three patients (10 men, 13 women; mean age at surgery 57.9 years; mean follow-up periods 52.9 months) with occipitocervical junction disorders were treated by occipitocervical reconstruction using pedicle screws, aided by a CT-based navigation system. Roentgenologic measurement and clinical evaluation were performed before surgery and at final follow-up. Postoperative CT and plane radiographs were used to determine the accuracy of screw placement. RESULTS Mean atlantodental interval and Ranawat value were significantly improved (P<.05), and mean clivoaxial angle was increased after surgery and maintained at final follow-up. Mean Japanese Orthopedic Association score before and at final follow-up was 7.1 ± 4.4 and 11.3 ± 3.5 points, showing significant improvement (P = .005). Fourteen patients (61%) improved more than one Ranawat grade. Six of nine patients (67%) in class IIIB were improved. On the other hand, nine patients (39 %) remained at the same class at final follow-up. A total of 88 pedicle screws were inserted into cervical and upper thoracic pedicles using the navigation system, and only one screw (1.1 %) showed major pedicle wall perforation. Solid union was achieved in all 23 patients. CONCLUSIONS Occipitocervical reconstruction using pedicle screws provided a high fusion rate and maintained alignment in the occipitocervical region. The computer-assisted navigation system was a useful tool for accurate and safe pedicle screw insertion.

A case of mucopolysaccharidosis IV with lower leg paresis due to thoraco-lumbar kyphoscoliosis

We treated a patient of type IV mucopolysaccharidosis (Morquios disease) with lower leg paresis due to kyphoscoliosis. A 65-year-old woman presented with Morquios disease. A lateral radiograph demonstrated the classic bullet-shaped vertebrae and a 65 degrees thoraco-lumbar kyphosis. After the age of 60, she suffered from numbness in both lower legs and walking disturbance. Bilateral patellae-tendon reflexes were exaggerated. MRI showed compression of the spinal cord around T12 to L2 with a highlighted area of change inside the spinal cord. Myelography and computed tomography after the myelography showed narrowing of the sub-arachnoidal space and deformation of the spinal cord around the T12 to L2 levels. Severe vertebral osteoporosis made it necessary to first perform posterior correction of the kyphosis and fusion. The curve was stabilised with the Luque method from T7 to L4. Her neurological condition markedly recovered, but 1 year after surgery her neurological condition again began to deteriorate, resulting in walking disturbance. For this reason, anterior decompression and fusion through a lateral thoracotomy was undertaken. Decompression of the spinal cord and a bone graft from the iliac crest were attained. The patients neurological condition again improved, but not as much as immediately after the first operation.

Pedicle morphology using computed tomography-based navigation system in adolescent idiopathic scoliosis.

Study Design/Setting: Retrospective study. Objective: The purpose of this study was to use multidimensional analysis with a computed tomography (CT)-based navigation system to measure the outer cortical diameter and the maximum screw trajectory length of the pedicle of the thoracic and lumbar regions of the spine in adolescent idiopathic scoliosis (AIS) patients. Another objective was to identify pedicles that require cautious insertion of screws. Summary of Background Data: Pedicle diameter in AIS patients was narrower on the concave side of the scoliotic curve. Many researchers have measured pedicle diameter and length of AIS patients by using standard CT or magnetic resonance imaging (MRI), but only few have used 3-dimensional imaging, especially CT-based navigation. Methods: Fifteen patients with right-side thoracic AIS who underwent pedicle screw fixation were studied. A CT-based navigation system was used to measure the pedicle diameter, defined as the widest outer cortical diameter at the narrowest part of the pedicle. Moreover, the maximum pedicle screw trajectory length was measured as the distance between the posterior cortical entry point of the pedicle screw and the anterior vertebral cortex in line with the axis of the pedicle between T1 and L5. In addition, the values of each parameter taken using the CT navigation system and the standard axial CT were compared. Results: Pedicles on the concave side of the main thoracic curve apex and proximal thoracic curve tended to have the narrowest diameters. The mean length of the longest screw that could be fixed was longer on the right side, except for T8 and T9. Our data showed screw size feasibility as follows: 25 or 30 mm screws were feasible from T1 to T5; 30 or 35 mm screws, from T6 to T12; and 35 or 40 mm screws, from L1 to L5. Pedicle diameter measured by the CT navigation system was larger than that measured by standard axial CT. Left-side pedicle length measured by the CT navigation system was lesser than that measured by standard axial CT. Conclusions: Pedicle diameter in patients with AIS is narrower on the concave side of the scoliotic curve, and therefore, caution should be exercised during screw insertion on the concave side.

Comparison of Clinical and Radiological Results of Posterolateral Fusion and Posterior Lumbar Interbody Fusion in the Treatment of L4 Degenerative Lumbar Spondylolisthesis

Study Design Multicenter analysis of two groups of patients surgically treated for degenerative L4 unstable spondylolisthesis. Purpose To compare the clinical and radiographic outcomes of posterolateral fusion (PLF) and posterior lumbar interbody fusion (PLIF) for degenerative L4 unstable spondylolisthesis. Overview of Literature Surgery for lumbar degenerative spondylolisthesis is widely performed. However, few reports have compared the outcome of PLF to that of PLIF for degenerative L4 unstable spondylolisthesis. Methods Patients with L4 unstable spondylolisthesis with Meyerding grade II or more, slip of >10° or >4 mm upon maximum flexion and extension bending, and posterior opening of >5 degree upon flexion bending were studied. Patients were treated from January 2008 to January 2010. Patients who underwent PLF (n=12) and PLIF (n=19) were followed-up for >2 years. Radiographic findings and clinical outcomes evaluated by the Japanese Orthopaedic Association (JOA) score were compared between the two groups. Radiographic evaluation included slip angle, translation, slip angle and translation during maximum flexion and extension bending, intervertebral disc height, lumbar lordotic angle, and fusion rate. Results JOA scores of the PLF group before surgery and at final follow-up were 12.3±4.8 and 24.1±3.7, respectively; those of the PLIF group were 14.7±4.8 and 24.2±7.8, respectively, with no significant difference between the two groups. Correction of slip estimated from postoperative slip angle, translation, and maintenance of intervertebral disc height in the PLIF group was significantly (p<0.05) better than those in the PLF group. However, there was no significant difference in lumbar lordotic angle, slip angle and translation angle upon maximum flexion, or extension bending. Fusion rates of the PLIF and PLF groups had no significant difference. Conclusions The L4–L5 level posterior instrumented fusion for unstable spondylolisthesis using both PLF and PLIF could ameliorate clinical symptoms when local stability is achieved.