Takeshi Aoyama

A new ceramic interspinous process spacer for lumbar spinal canal stenosis.

OBJECTIVE Because surgery in elderly patients should be minimally invasive, interspinous process distraction has been widely used in this group to treat lumbar canal stenosis. We developed a new interspinous process distraction spacer composed of hydroxyapatite ceramic. In this work, we demonstrate the usefulness of this novel device. METHODS Since 2003, we operated on 19 elderly patients with lumbar canal stenosis, including 14 men and five women. Their mean age was 70.1 years. We compared the intervertebral angle, posterior disc height, and interspinous process distance on midsagittal magnetic resonance images obtained before and after the surgery. We also assessed clinical outcomes by using the Visual Analog Scale and the Zurich Claudication Questionnaire. RESULTS The average operation time per level was 44.7 minutes. Postoperatively, there were significant changes in the angle (from 12.5 to 8.6 degrees, P < 0.0001), the posterior disc height (from 10.6 to 13.1 mm, P < 0.0001), and the interspinous process distance (from 9.7 to 14.1 mm, P < 0.0001). The clinical outcomes, which we assessed by using the Visual Analog Scale and the Zurich Claudication Questionnaire, were considered satisfactory. (Visual Analog Scale, from 6.88 to 3.00; Zurich Claudication Questionnaire, symptom severity domain from 2.94 to 1.92, physical function from 2.51 to 1.73.) CONCLUSION Our ceramic spacer is useful in the treatment of elderly patients with lumbar canal stenosis. Treatment comprises an easy surgical procedure and produces no metal artifact on radiological evaluations, such as magnetic resonance imaging and computed tomographic scans.

Surgical Outcomes of High-Grade Spinal Cord Gliomas

Study Design A retrospective study. Purpose The purpose of this study was to obtain useful information for establishing the guidelines for treating high-grade spinal cord gliomas. Overview of Literature The optimal management of high-grade spinal cord gliomas remains controversial. We report the outcomes of the surgical management of 14 high-grade spinal glioma. Methods We analyzed the outcomes of 14 patients with high-grade spinal cord gliomas who were surgically treated between 1989 and 2012. Survival was charted with the Kaplan-Meier plots and comparisons were made with the log-rank test. Results None of the patients with high-grade spinal cord gliomas underwent total resection. Subtotal resection was performed in two patients, partial resection was performed in nine patients, and open biopsy was performed in three patients. All patients underwent postoperative radiotherapy and six patients further underwent radiation cordotomy. The median survival time for patients with high-grade spinal cord gliomas was 15 months, with a 5-year survival rate of 22.2%. The median survival time for patients with World Health Organization grade III tumors was 25.5 months, whereas the median survival time for patients with glioblastoma multiforme was 12.5 months. Both univariate and multivariate Cox proportional hazards models demonstrated a significant effect only in the group that did not include cervical cord lesion as a factor associated with survival (p=0.04 and 0.03). Conclusions The surgical outcome of patients diagnosed with high-grade spinal cord gliomas remains poor. Notably, only the model which excluded cervical cord lesions as a factor significantly predicted survival.

Clinical Factors for Prognosis and Treatment Guidance of Spinal Cord Astrocytoma

Study Design Retrospective study. Purpose To obtain information useful in establishing treatment guidelines by evaluating baseline clinical features and treatment outcomes of patients with spinal cord astrocytoma (SCA). Overview of Literature The optimal management of SCA remains controversial, and there are no standard guidelines. Methods The study included 20 patients with low-grade and 13 with high-grade SCA surgically treated between 1989 and 2014. Patients were classified according to the extent of surgical resection. Survival was assessed using Kaplan–Meier plots and compared between groups by log-rank tests. Neurological status was defined by the modified McCormick scale and compared between groups by Mann–Whitney U tests. Results Surgical resection was performed for 19 of 20 low-grade (95%) and 10 of 13 high-grade (76.9%) SCA patients. Only nine patients (27.3%) underwent gross total resection, all of whom had low-grade SCA. Of all patients, 51.5% showed deteriorated neurological status compared to preoperative baseline. Median overall survival was significantly longer for low-grade SCA than that (91 months, 78% at 5 years vs. 15 months, 31% at 5 years; p=0.007). Low-grade SCA patients benefited from more aggressive resection, whereas high-grade SCA patients did not. Multivariate analysis revealed histology status (hazard ratio [HR], 0.30; 95% confidence interval [CI], 0.09–0.98; p<0.05) and postoperative neurological status (HR, 0.12; CI, 0.02–0.95; p<0.05) as independent predictors of longer overall survival. Adjuvant radiotherapy had no significant impact on survival rate. However, a trend for increased survival was observed with radiation cordotomy (RCT) in high-grade SCA patients. Conclusions Aggressive resection for low-grade and RCT may prolong survival. Preservation of neurological status is an important treatment goal. Given the low incidence of SCA, establishing strong collaborative, interdisciplinary, and multi-institutional study groups is necessary to define optimal treatments.

Detection of Residual Disc Hernia Material and Confirmation of Nerve Root Decompression at Lumbar Disc Herniation Surgery by Intraoperative Ultrasound

The aim of lumbar disc herniation surgery is the removal of herniated disc material (HDM) and complete decompression of the nerve root. As some patients present with residual HDM, we examined the ability of intraoperative ultrasound (IOUS) to detect this material. Between February 2006 and June 2007, we used IOUS in 30 patients undergoing surgery for lumbar disc herniation. They were 17 men and 13 women; their ages ranged from 22 to 63 y (mean 44.0 y). The level surgically addressed was L3/4 in 1, L4/5 in 14 and L5/S1 in 15 patients; they were operated in the prone position. After placing a 3-4 cm midline skin incision, partial hemi-semilaminotomy was performed. HDM was removed through a bone window; a surgical microscope was used during the operation. After removal was judged as adequate, IOUS was performed; 17 patients also underwent IOUS before removal of the herniated disc. For the acquisition of IOUS images, we used LOGIQ 9 and 8c microconvex probes (GE Healthcare, Wauwatosa, WI, USA). The normal anatomical structures were well visualized. HDM was iso- to hyperechoic compared with normal nerve tissue. In three of 17 patients, the dural sac and nerve root could not be distinguished from HDM before removal, although in all 30, the decompressed dural sac, intradural cauda equina and nerve root were well visualized. We posit that the echogenicity of nerve tissue was raised due to compression, rendering it similar to that of the herniated disc. In two patients, IOUS detected residual disc material; the surgical procedure was resumed and sufficient removal was accomplished. IOUS monitoring is safe, convenient and inexpensive. It is also highly useful for the detection of residual HDM and the confirmation of adequate nerve root decompression.

Brain stem arteriovenous malformation with large venous varix.

The case of a patient with arteriovenous malformation (AVM) with a venous varix that occurred at the medulla oblongata is reported. The AVM bled twice in a short period. The AVM was fed by the small ramus, possibly the anterior spinal artery, originating from the right distal vertebral artery and draining into a large venous varix and then into the venous systems surrounding the brain stem. The obstruction of the feeding artery was performed, and the varix subsequently disappeared. The remaining abnormal vasculature was then treated with stereotactic radiosurgery. The treatment of an AVM at the medulla oblongata is still challenging, but the appropriate combination of modalities will improve the patient outcome.

Analysis of Radiological Factors Promoting Degeneration in Adjacent Disc Levels after Anterior Cervical Discectomy and Fusion

頚椎前方固定術における固定隣接椎間障害の画像的因子解析 矢野俊介 飛

Volume rendering for computer generated holograms

CT (Computer Tomography) and MRI (Magnetic Resonance Imaging) provide three-dimensional data of invisible objects, which is called volume data. Volume rendering technique shows us realistic 2D images from the 3D data. In this paper, we propose a new calculation method of computer generated holograms incorporating volume rendering technique in order to create autostereoscopic images. Using the method, the fringe pattern on the hologram is calculated from the 3D data directly without intermediate process. Optical experiments were done using phantom objects and the results show that the method represents full-parallax 3D images.