Tatsuro Aoyama

Description and first clinical application of AirWay Scope for tracheal intubation.

We have developed a novel airway apparatus, AirWay Scope, which we have used in the orotracheal intubation of 10 consecutive patients requiring general anesthesia before neurosurgical procedures. The characteristic shape of the introducer (INTLOCK), the tube guiding function and the sighting device of the AirWay Scope has possibility to facilitate tracheal intubation. Here, we report the first clinical application of this system and describe potential advantages of the apparatus.

Utility of nonpenetrating titanium clips for dural closure during spinal surgery to prevent postoperative cerebrospinal fluid leakage

OBJECT The nonpenetrating titanium clip has been successfully used in peripheral arterial bypass surgery. The purpose of this study was to evaluate the leakage pressures and patterns of nonpenetrating titanium clips using a simple model that mimicked spinal surgery. In addition, the authors describe their surgical experience with these clips and the follow-up results in 31 consecutive patients. METHODS The authors compared nonpenetrating titanium clips and expanded polytetrafluoroethylene (ePTFE) sutures in relation to the water pressure that could be tolerated by sutured ePTFE sheets, and the leakage pressure patterns were determined. The changes in leakage pressures at 5 minutes, 30 minutes, and 12 hours were examined when the clips and sutures were used in combination with the mesh-and-glue technique in an in vitro study. Thirty-one patients underwent spinal intradural procedures using nonpenetrating titanium clips to suture the dura maters using the meshand-glue technique, involving fibrin glue and polyglycolic acid-fibrin sheets. RESULTS A significant difference was apparent between the ePTFE suture group and the nonpenetrating titanium clip group, with the latter showing a leakage pressure that could be sustained and was 1508% higher than that of the former (p = 0.001). In relation to leakage patterns, the nonpenetrating titanium clips did not make any suture holes in the ePTFE sheet and fluid leakage occurred between the clips, whereas fluid leakage was associated with the pressure elevation that occurred at the suture holes made by the ePTFE sutures. Of the 31 patients who underwent spinal intradural procedures using nonpenetrating titanium clips, 1 (3.2%) experienced cerebrospinal fluid (CSF) leakage postoperatively. No other complications-for example, allergic reactions, adhesions, or infections--were encountered. CONCLUSIONS The interrupted placement of nonpenetrating titanium clips enables dural closure without creating any holes. These clips facilitate improvements in the initial leakage pressure and reduce postoperative CSF leakage following spinal surgery. The authors conclude that it is very beneficial to suture the spinal dura mater using nonpenetrating titanium clips given the anatomical characteristics of the spinal dura mater and the fact that the clips do not create suture holes.

Surgical strategy and results of treatment for dumbbell-shaped spinal neurinoma with a posterior approach.

Abstract Objective. Total removal of neurinomas is generally an achievable goal that yields good results; however, dumbbell-shaped neurinomas often present challenges for complete resection. Some extensive surgical approaches for complete removal have been reported to lead to severe complications. Therefore, the surgical strategy for dumbbell-shaped neurinomas is controversial. Methods. Twelve patients with dumbbell-shaped neurinomas were surgically treated in our hospital over 5 years. We adopted a posterior approach to remove the intracanalicular portion of the neurinomas as completely as possible, intentionally leaving the foraminal portion unresected to prevent bony and vascular insult. We investigated the postoperative surgical results and complications and the regrowth rate of the remnant lesions. Results. Postoperative residual tumours were identified in 6 of the 12 patients. The perioperative neurological findings between the two groups were almost the same. The recurrence rate was low. Severe surgery-related complications occurred in only one patient with mild and temporary motor weakness. Conclusion. Our strategy demonstrated low rates of recurrence and complications compared with those accompanying the extensive alternative approaches that have been reported previously. Our case series showed that subtotal removal of dumbbell-shaped neurinomas using a posterior approach is a safer, more effective, and more minimally invasive treatment.

Isolated primary malignant lymphoma arising from the optic chiasm.

Isolated primary malignant lymphoma rarely arises from the anterior visual pathway. A 59-year-old previously healthy man presented with progressive, painless, bilateral visual disturbance. Neurological imaging revealed an enhancing mass arising from the optic chiasm. Open biopsy was carried out under monitoring of visual evoked potentials and a histopathological diagnosis of diffuse large B-cell lymphoma was made. As systemic examination did not show any evidence of systemic lymphoma, we concluded that this patient had an isolated primary malignant lymphoma at the anterior visual pathway.

Bony surface registration of navigation system in the lateral or prone position: technical note

BackgroundNavigation systems have become essential tools in neurosurgery. Precise registration is indispensable for the accuracy of navigation. The rapid and precise registration by surface matching on the facial skin is possible using the landmarks of the face in the supine position. On the other hand, incomplete registration often occurs in the lateral or prone position due to the direction of the face and displacement of the skin by headpins and obscuring of the skin by the bispectral index monitor and many electrodes on the forehead as well as the eye patch. Surface matching on the occipital scalp is not suitable for registration because the shape of the occipital scalp is flat and it is compressed in the supine position when obtaining preoperative neuroimaging. To overcome this problem, the authors have developed a new method of registration designated as “bony surface registration” in which surface matching is achieved using the bony surface of the skull after exposure.MethodsBetween June and December 2014, this technique was used in 23 patients and its effectiveness was examined.ResultsRegistration time was markedly shortened and useful navigation was achieved due to accurate registration in all patients.ConclusionsThis is the first report of a registration methodology for a navigation system in the lateral or prone position. This bony surface registration method is useful for navigation system image-guided surgery in the lateral or prone position.

Investigation of radiofrequency-induced temperature elevation of aneurysm clips in a 3.0-tesla magnetic resonance environment.

OBJECTIVEBurn injuries associated with excessive heating of medical metallic devices have been reported, but a definite mechanism for magnetic resonance imaging-induced heating remains unresolved. The aim of this study is to evaluate temperature elevation of metallic wires, aneurysm clips, and clips attached to metallic wires under 3.0-T magnetic resonance imaging. METHODSThe temperature of the metallic wires, the aneurysm clips, and the clips attached to the metallic wires was measured with a fiber optic thermometer sensor system. RESULTSAlthough the specific absorption rate was less than that observed during standard use, the temperature rapidly increased in the metallic wire. Furthermore, temperature elevation was observed when the clips were attached to metallic wires. On the other hand, not all clips showed obvious temperature elevation when they were placed alone in a 3.0-T magnetic resonance imaging environment. CONCLUSIONAneurysm clips, when placed alone in a 3.0-T magnetic resonance imaging environment, are confirmed to be safe during temperature elevation.

Posterior Laminoplastic Laminotomy Combined with a Paraspinal Transmuscular Approach for Removing a Lumbar Dumbbell-shaped Schwannoma: A Technical Note

The surgical strategies and methods used to treat dumbbell-shaped tumors located in the lumbar-foraminal region are controversial. Although a total facetectomy and combined intra- and extraspinal canal approach provide a wide operative field, facet fusion is required, which can be rather invasive. Here, we report a successful removal of a lumbar dumbbell-shaped schwannoma using a combined laminoplastic laminotomy with Wiltse’s paraspinal surgical approach. This was performed under an operating microscope without a complete facetectomy, fusion, and posterior fixation. Briefly, we treated two patients with lumbar foraminal tumors, both dumbbell-shaped schwannomas located in the intra- and extradural portion. After a laminoplastic laminotomy, the intradural tumor was removed. The tumor located at the extracanalicular site was removed after drilling the pars interarticularis of the lamina, which was performed to enlarge the intervertebral foramen via Wiltse’s paraspinal surgical approach. During surgery, facetectomy with posterior fixation was not needed to remove the intraforaminal component. There was no lumbar instability or complication after surgery. Our results suggest that a combined posterior laminoplastic laminotomy and Wiltse’s paraspinal surgical approach is useful and less invasive for treating patients with lumbar foraminal tumors.

Radiographic measurements of C-2 in patients with atlas assimilation.

OBJECT The object of this study was to evaluate the radiographic characteristics of C-2 using multiplanar CT measurements for anchor screw placement in patients with C-1 assimilation (C1A). Insertion of a C-2 pedicle screw in the setting of C1A is relatively difficult and technically demanding, and there has been no report about the optimal sizes of the pedicles and laminae of C-2 for screw placement in C1A. METHODS An institutional database was searched for all patients who had undergone cervical CT scanning and cervical spine surgery between April 2006 and December 2012. Two neurosurgeons reviewed the CT scans from 462 patients who met these criteria, looking for C1A and other anomalies of the craniocervical junction such as high-riding vertebral artery (VA), basilar invagination, and VA anomaly. The routine axial images were reloaded on a workstation, and reconstruction CT images were used to measure parameters: the minimum width of bilateral pedicles and laminae and the length of bilateral laminae of the atlas. RESULTS Seven patients with C1A were identified, and 14 sex-matched patients without C1A were randomly selected from the same database as a control group. The mean minimum pedicle width was 5.21 mm in patients with C1A and 7.17 mm in those without. The mean minimum laminae width was 5.29 mm in patients with C1A and 6.53 mm in controls. The mean minimum pedicle and laminae widths were statistically significantly smaller in the patients with C1A (p < 0.05). CONCLUSIONS In patients with C1A, the C-2 bony structures are significantly smaller than normal, making C-2 pedicle screw or translaminar screw placement more difficult.

Expression of the JAK/STAT signaling pathway in the ligamentum flavum of patients with lumbar spinal canal stenosis

BACKGROUND Ligamentum flavum (LF) hypertrophy is an important cause of lumbar spinal canal stenosis (LSS), one of the most common spinal disorders in the elderly. Although many cytokines are reported to be associated with LF hypertrophy, the intracellular signaling system is rarely discussed. The purpose of this study was to identify the JAK/STAT signaling pathway and to examine the role of the JAK/STAT systems in the hypertrophied LF. METHODS The LF of 10 LSS patients was analyzed and the expression of JAK1, STAT3, phosphorylated (p)-STAT3, and actin was examined by Western blot analysis. The expression of p-STAT3 was also examined by immunostaining and its positive cell ratio was compared between LSS and non-LSS samples. We measured the thickness of the LF on magnetic resonance images and studied the relationship between its thickness and the expression of p-STAT3. RESULTS JAK1, STAT3, and p-STAT3 were detected in almost all samples by Western blot analysis. Immunoreactivity against p-STAT3 was observed mainly in endothelial- and fibroblast-like cells. The expression of p-STAT3 was significantly higher in LSS than non-LSS samples; it was significantly stronger on the dorsal than the dural side of the LF and positively correlated with the thickness of the LF on the dorsal side. CONCLUSIONS The JAK/STAT signaling pathway is positively correlated with the thickness of the LF. Our findings suggest that JAK1 and STAT3 molecules are involved in and regulate LF hypertrophy.

Relationship Between Muscle Dissection Method and Postoperative Muscle Atrophy in the Lateral Suboccipital Approach to Vestibular Schwannoma Surgery.

BACKGROUND Various techniques are available for occipital skull exposure with muscle dissection, as well as different types of skin incisions in the lateral suboccipital approach to vestibular schwannoma (VS) surgery. The skin incisions are generally classified as S-shaped, J-shaped, or C-shaped. In each method, the technique used for muscle dissection differs in terms of cut, single layer, and multiple layers. This study was performed to identify the relationships among muscle dissection method, skin incision type, and muscle atrophy in the lateral suboccipital approach to surgery for VS. METHODS Between 2002 and 2011, we performed surgical resection in 53 patients with VS at Shinshu University Hospital. Of these 53 patients, 35 with radiographic annual follow-up for >3 years after surgery were evaluated retrospectively. These patients included 14 who underwent an S-shaped incision, 6 with a J-shaped incision, and 15 with a C-shaped incision. Bilateral areas of the skin and occipital muscles were measured, and rates of atrophy were calculated and compared among the 3 methods. RESULTS Postoperative muscle atrophy was significantly advanced in the second postoperative year, but did not tend to develop further after the third year. The postoperative muscle atrophy ratio was significantly lower in the C-shaped incision group (mean ± SD, 4.0% ± 6.9%) compared with the S-shaped (17.1% ± 9.8%) and J-shaped (17.6% ± 10.0%) incision groups within 2 years after surgery (P < 0.05). CONCLUSIONS The C-shaped skin incision with multilayer muscle dissection was associated with significantly reduced postoperative muscle atrophy compared with the other methods.