Hiroki Matsui

Bone union rate with autologous iliac bone versus local bone graft in posterior lumbar interbody fusion.

Study Design. A retrospective clinical study with a long-term follow-up in a single facility. Objective. The purpose of this study is to compare bone union rate between autologous iliac crest bone graft and local bone graft in patients treated by posterior lumbar interbody fusion (PLIF) using carbon cage for single-level interbody fusion. Summary of Background Data. Recently, a number of authors have reported on local bone grafting using bone that is obtained from laminectomy, and have indicated that the achieved fusion rate is similar to that of autologous iliac bone grafting. However, there is no report comparing the fusion rates between autologous iliac bone and local bone graft with a detailed follow-up of fusion progression. Methods. The subjects were 101 patients whose course could be observed for at least 2 years. The diagnosis was lumbar spinal canal stenosis in 14 patients, herniated lumbar disc in 19 patients, and degenerative spondylolisthesis in 68 patients. Single interbody PLIF was performed using iliac bone graft in 54 patients and local bone graft in 47 patients. Existence of pseudarthrosis on X-P (anteroposterior and lateral view) was investigated during the same follow-up period. Results. No significant differences were found in operation time and blood loss. Significant differences were also not observed in fusion grade at any follow-up period or in fusion progression between the 2 groups. Donor site pain continued for more than 3 months in 6 cases (11%). The final fusion rate was 94.5% versus 95.8%. Conclusion. Fusion results from the local bone group and the autologous iliac bone group were nearly identical. Furthermore, fusion progression was nearly identical. Complications at donor sites were seen in 17% of the cases. From the aforementioned results, it was concluded that local bone graft is as beneficial as autologous iliac bone graft for PLIF at a single level.

The cutoff amplitude of transcranial motor-evoked potentials for predicting postoperative motor deficits in thoracic spine surgery.

Study Design. Prospective clinical study of intraoperative transcranial motor-evoked potentials (TcMEP) amplitudes and postoperative motor deficits. Objective. To determine the cutoff amplitude during intraoperative TcMEP monitoring for predicting postoperative motor deficits after thoracic spine surgery. Summary of Background Data. Several alarm points when monitoring with TcMEP have been advocated, but there have been no reports on an actual cutoff amplitude of TcMEP for predicting the occurrence of postoperative motor deficits. Methods. Among 80 consecutive surgical cases, 28 had a deterioration in TcMEP amplitude in at least 1 monitored muscle during surgery. We examined intraoperative electrophysiological changes and postoperative motor deficits in 270 monitorable muscles in those 28 patients. Through receiver operating characteristic curve analysis, we identified the cutoff amplitudes at the intraoperative point of deterioration and at the end of surgery for predicting postoperative motor deficits in both relative and absolute values. Results. The relative and the absolute cutoff amplitudes of TcMEP at the intraoperative point of deterioration and at the end of thoracic spine surgery were 12% of control amplitude and 1.9 &mgr;V and 25% of control amplitude and 3.6 &mgr;V, respectively. Sensitivity/specificity for those cutoff points are 88%/64%, 69%/83%, 90%/64%, and 70%/82%, respectively. Conclusion. We determined the cutoff amplitude for predicting postoperative motor deficits in thoracic spine surgery. The results may help establish the alarm criteria for thoracic spine surgery.

Differentiation of Spinal Schwannomas and Myxopapillary Ependymomas: MR Imaging and Pathologic Features

Study Design: Retrospective clinical study. Objective: The objective of this study is to evaluate magnetic resonance imaging and pathologic features of spinal schwannomas (SCHs) and myxopapillary ependymomas (MPEs) with focus on differentiating 2 disease entities. Summary of Background Data: Few studies have reported on the differentiation of SCHs and MPEs. Methods: Fifty-three patients were retrospectively reviewed with histologically confirmed spinal SCHs (41 patients) or MPEs (12 patients) of the cauda equina and/or conus medullaris. We evaluated neurological deterioration after surgery in association with the intraoperative findings of the tumor, as well as with the preoperative magnetic resonance images and postoperative histologic findings. Results: Patients in the SCH group had a greater mean age at surgery and a greater mean disease duration. In the SCH group, all 24 tumors that were homogeneously hyperintense on the T2-weighted (T2W) images showed rim enhancement on the postcontrast T1-weighted (T1W) images. Moreover, all 14 of the SCHs with homogeneous enhancement on the postcontrast T1W images were isointense on the T2W images. However, in the MPE group, all 8 of the tumors that were homogeneously hyperintense on T2W images showed homogeneous enhancement on their postcontrast T1W images. Conclusions: It is very important to differentiate SCHs and MPEs before surgery, because there are reported cases of dissemination of MPEs through cerebrospinal fluid throughout the neuraxis; the tumor must be removed en block to prevent this. Although MPEs and SCHs may have similar imaging characteristics, detailed examination of the magnetic resonance T2W image and postcontrast T1W image facilitates their differentiation.

Clinical Outcome of Treatments for Spinal Dural Arteriovenous Fistulas : Results of Multivariate Analysis and Review of the Literature

Study Design. This study was a case series study using a prospective single-institute database for the treatment of spinal dural arteriovenous fistulas (SDAVFs). Objective. To evaluate clinical factors that influence the neurological outcomes of treatment for SDAVFs, which were obtained from the analysis of 21 patients treated in our institution, and to provide management recommendations based on the review of former major clinical studies including our own reported over the past 2 decades. Summary of Background Data. Since 1977, when Kendall and Logue described the etiology of SDAVFs as hyperpressure of intrathecal veins due to an abnormal shunting from the arteries, treatment strategies have improved dramatically along with developments in neuroimaging, endovascular techniques and materials, and microsurgery based on the underlying pathophysiological process. However, therapeutic guidelines remain controversial. Methods. Patients treated for SDAVFs from 2000 to 2008 were eligible. Age, sex, level of shunting, initial symptom, duration of symptom, the treatment method, and clinical symptoms before and 6 months after treatment were investigated. Results. There were a total of 30 patients (18 male and 12 female), with a mean age of 59 years; 21 of them underwent treatment for the first time. We conducted a univariate analysis using a logistic regression model, on age, sex, the level of SDAVFs, duration of symptoms, symptom (sensory or paralysis), and gait function and micturition before treatment, and the intervention method were set as variables to investigate the risk factors for motor deficit 6 months after the treatment. Only gait function before treatment was correlated with the motor deficit 6 months after treatment (odds ratio = 10.0; 95% confidence interval = 1.28–78.11, P = 0.03). From these results, intervention at an early stage would be the key to a preferable outcome of the treatment for SDAVFs. Conclusion. The clinical status before treatment significantly influenced the clinical outcome after the treatment.

Keratan sulfate expression in microglia is diminished in the spinal cord in experimental autoimmune neuritis

Experimental autoimmune neuritis (EAN) is an animal model of Guillain–Barré syndrome, an inflammatory demyelination disease of the peripheral nervous system. Although this disease has been extensively studied on peripheral nerves, the pathology of the central nervous system has not been fully understood. Previous studies demonstrate that expression of keratan sulfate (KS), the sugar chain of proteoglycan, is associated with activated microglia/macrophages accumulated after neuronal injuries. Unexpectedly, we found here that KS is rather diminished in rat EAN. KS was restrictively expressed in microglia in the spinal cord of normal rats. KS was positive in 50% microglia in the ventral horn and 20% in the dorsal horn. In EAN, microglia increased in number and expressed the activation marker CD68, but KS expression was abolished. Concomitantly, pro-inflammatory cytokines, i.e., interferon (IFN)-γ, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α, were increased in the spinal cord of EAN rats, whereas anti-inflammatory cytokines, such as IL-4 and IL-10, were decreased. In addition, silencing of KSGal6ST attenuated KS expression on the primary cultured microglia and upregulated expression of some activation markers (TNF-α, IL-1β, and iNOS) under the stimulation with lipopolysaccharide and IFN-γ. This study demonstrates for the first time a close association of EAN and disappearance of KS on microglia. KS expression could be a useful marker to evaluate the status of polyneuropathy.

Surgical treatment for chronic atlantoaxial rotatory fixation in children.

Six consecutive pediatric patients with chronic atlantoaxial rotatory fixation (AARF) underwent posterior fixation. All patients were first treated conservatively such as with a neck collar, traction, Minerva jacket, or halo-vest; however, they failed to achieve successful reduction because of the C2 facet deformity or C1–2 facet fusion. We performed C1–2 fusion using a C1 lateral mass screw and a C2 pedicle screw, a C1–2 transarticular screw, or an occipitocervical fusion using a rod and wiring system. Five patients achieved solid fusion with no torticollis or neck pain by the final follow-up. One patient had mild torticollis after surgery but no pain. Although we believe that with early diagnosis of AARF and appropriate conservative treatment we can avoid surgery, even with conservative treatment from the onset of symptoms, five patients in our series required surgery because conservative treatment did not lead to successful reduction. When conservative treatment for chronic AARF patients fails, C1–2 transarticular fixation, and C1 lateral mass screw and C2 pedicle screw fixation are reliable methods to treat these patients.

Single-stage removal of thoracic dumbbell tumors from a posterior approach only with costotransversectomy.

Purpose Thoracic dumbbell tumors are relatively rare, usually arising from neurogenic elements. Methods for surgical removal thereof remain controversial. The purpose of this study was to evaluate the surgical results of a single-stage posterior approach with laminectomy and costotransversectomy only for the management of thoracic dumbbell tumors. Materials and Methods Eight cases of thoracic large dumbbell tumor were analyzed retrospectively: seven men and one woman (mean age, 49 years). Pathologic findings included schwannoma in five patients, neurofibroma in two patients (Recklinghausen in one patient), and ganglioneuroma in one patient. All patients underwent single-stage removal of dumbbell tumors by a posterior approach followed by laminectomy and costotransversectomy combined with instrumentation. Clinical and radiologic outcomes were reviewed, thereafter. Results Operative time ranged from 185 to 420 minutes (mean, 313 minutes), with estimated blood loss ranging from 71 to 1830 mL (mean, 658 mL). Postoperative complications included atelectasis in one case. All patients had tumors successfully removed with no neurological deterioration. Spinal deformities were not observed in any patients at the last follow-up (mean, 52 months), with instrumentation. Conclusion Single-stage surgery with laminectomy and costotransversectomy may be useful for removing thoracic dumbbell tumors without a combined anterior approach.

Singularity categories and singular equivalences for resolving subcategories

Let

A case of split notochord syndrome: An adult with a spinal endodermal cyst mimicking an intramedullary tumor

\mathcal {X}