Takashi Watanabe

Primary epithelioid hemangioendothelioma originating in the lower petroclival region: Case report

BACKGROUNDnWe report the first case of primary epithelioid hemangioendothelioma (EH) originating in the lower petroclival region.nnnCASE DESCRIPTIONnA 55-year-old female presented with a 45-year history of subclinical atrophy on the right side of her tongue and a 15-year history of hoarseness. Neuroimaging revealed an expansile, homogeneously enhanced intraosseous mass with bony shell and honeycomb configuration in the petroclival region. A right far lateral transcondylar approach was utilized for subtotal removal of the tumor, which demonstrated high vascularity in the petroclival bone. Histopathological and immunohistochemical examination confirmed the diagnosis of EH. Because of the intermediate malignancy, adjuvant gamma knife radiotherapy was performed for the residual mass 5 months after surgery.nnnCONCLUSIONnEH rarely occurs in the skull base region. The appearance of surrounding bony structure and rich vascularity are important findings for the differential diagnosis. A far lateral transcondylar approach provides sufficient exposure of the jugular tubercle and lower clivus. Additional radiotherapy may be recommended for residual tumors with a high MIB-1 labeling index.

Analysis of Impact Response of Sand Cushion for Rockfall by Distinct Element Method

In order to know efficiently the impact behavior of the actual size sand cushion under rock fall, to achieve a lot of impact experiments under various conditions or to analyze those phenomena by use of reliable accurate methods is generally required. However, there is difficulty in many cases to achieve experiments because of financial reason. Therefore, the analysis method to reproduce full-scale impact behavior is indispensable. From this point of view, we have developed Distinct Element Method. The method to model the body to collide like a rock fall by an assembly of many small elements and the method to present a sand cushion as an assembly of many elements which have different size with randomness were shown. The validity of this method was shown by the comparison with experimental results.

High incidence and spontaneous resolution of mastoid effusion after craniotomy on early postoperative magnetic resonance images.

Mastoid effusion is a poorly understood complication after craniotomy. The incidence and severity of postoperative mastoid effusion were retrospectively examined on postoperative magnetic resonance (MR) images to assess any association with craniotomy procedures, time course, and neuro-otological complications. We evaluated the early postoperative MR images (within 4xa0days of craniotomy) and medical records of 74 patients who underwent 77 operations for the treatment of various intracranial diseases from January 2000 to December 2001. Mastoid effusion was classified into four grades: none, partial, moderate, and severe diffuse effusion in the mastoid air cells. Thirty-three follow-up MR images from 26 patients were also reviewed. Postoperative mastoid effusion occurred ipsilateral to the craniotomy site in 62 cases and contralateral in 56 cases. Mastoid effusion was significantly more severe ipsilateral than contralateral to craniotomy with exposure of the mastoid air cells (P<0.0001). There was no significant difference in severity between the contralateral and ipsilateral sides after craniotomy without mastoid air cell opening (P=0.437). Mastoid effusion following craniotomy without exposure of mastoid air cells resolved within 3xa0months. However, otitis media with effusion developed in six patients with severe mastoid effusion ipsilateral to craniotomy with exposure of the mastoid air cells. Mastoid effusion frequently developed on both sides. Any grade of mastoid effusion on the ipsilateral side to craniotomy without exposure of mastoid air cells, or on the contralateral side, was asymptomatic or had a benign course, and disappeared within 3xa0months.

Reliable and convenient method for the fixation of recording electrodes on nonshaved scalp for intraoperative electrophysiological monitoring: Technical note

BACKGROUNDnDifficulties with the intraoperative monitoring of evoked responses sometimes occur because of displacement or dislodgment of the recording electrodes during surgery, especially if placed on nonshaved scalp.nnnMETHODSnAn alternative fixation method of the recording electrode on the nonshaved scalp was developed. The sterile subdermal needle electrode was attached on the scalp by application of a transparent dressing (Tegaderm) over the electrode followed by fixing with a skin stapler.nnnRESULTSnThe needle electrodes were easily, quickly, and firmly positioned even on the nonshaved scalp. The responses of the intraoperative evoked potentials were highly stable and reproducible throughout the operation.nnnCONCLUSIONnThis fixation method for subdermal needle electrodes on the scalp is safe, reliable, and convenient for intraoperative electrophysiological monitoring of evoked potentials, even if the scalp is not shaved.

Carbon-Supported PtRuRh Nanoparticles as a Catalyst for Direct Ethanol Fuel Cells

Carbon-supported PtRuRh nanoparticles, PtRuRh/C, were prepared by an impregnation method as a new anode catalyst with a high activity for ethanol oxidation in a direct ethanol fuel cell (DEFC). PtRuRh (2:1:1)/C, of which the metal loading and the metal particle diameter was 40 wt% and 6.7 nm, respectively, with the metal composition of 2:1:1 for Pt:Ru:Rh, showed a higher oxidation current at a certain electrode potential compared to that of PtRu (1:1)/C and Pt/C prepared in a similar manner. The DEFC with PtRuRh (2:1:1)/C as the anode catalyst generated about a 1.5 times and 3 times higher electric power compared to that of PtRu (1:1)/C and Pt/C, respectively, with 2M ethanol.

Computer aided simulation surgery as an educational tool.

Before treating patients with acoustic tumors, doctors must take into account the benefits and risks resulting from the treatment. Information regarding risks includes the associated mortality and morbidity, such as cerebellar dysfunction, facial nerve palsy, and hearing loss.