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Postoperative Spinal Subdural Lesions Following Lumbar Spine Surgery: Prevalence and Risk Factors
Yukitaka Nagamoto,Shota Takenaka,Hiroyuki Aono 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.5
Study Design: Retrospective case–control study Purpose: To clarify the prevalence and risk factors for spinal subdural lesions (SSDLs) following lumbar spine surgery. Overview of Literature: Because SSDLs, including arachnoid cyst and subdural hematoma, that develop following spinal surgery are seldom symptomatic and require reoperation, there are few reports on these pathologies. No study has addressed the prevalence and risk factors for SSDLs following lumbar spine surgery. Methods: We conducted a retrospective analysis of the magnetic resonance (MR) images and medical records of 410 patients who underwent lumbar decompression surgery with or without instrumented fusion for degenerative disorders. SSDLs were classified into three grades: grade 0, no obvious lesion; grade 1, cystic lesion; and grade 2, lesions other than a cyst. Grading was based on the examination of preoperative and postoperative MR images. The prevalence of SSDLs per grade was calculated and risk factors were evaluated using multivariate logistic regression analysis. Results: Postoperative SSDLs were identified in 123 patients (30.0%), with 50 (12.2%) and 73 (17.8%) patients being classified with grade 1 and 2 SSDLs, respectively. Among these, one patient was symptomatic, requiring hematoma evacuation because of the development of incomplete paraplegia. Bilateral partial laminectomy was a significantly independent risk factor for SSDLs (odds ratio, 1.52; 95% confidence interval, 1.20–1.92; p <0.001). In contrast, a unilateral partial laminectomy was a protective factor (odds ratio, 0.11; 95% confidence interval, 0.03–0.46; p =0.002). Conclusions: The prevalence rate of grade 1 SSDLs was 30%, with no associated clinical symptoms observed in all but one patient. Bilateral partial laminectomy increases the risk for SSDLs, whereas unilateral partial laminectomy is a protective factor.
Kowatari Munehiko,Nagamoto Keisuke,Nakagami Koich,Tanimura Yoshihiko,Moritake Takashi,Kunugita Naoki 대한방사선방어학회 2022 방사선방어학회지 Vol.47 No.1
Background: For proper monitoring of the eye lens dose, an appropriate calibration factor of a dosimeter and information about the mean energies of X-rays are indispensable. The scattered X-ray energy spectra should be well characterized in medical practices where eye lenses of medical staffs might be high.Materials and Methods: Scattered X-ray energy spectra were experimentally derived for three different types of X-ray diagnostic and therapeutic equipment, i.e., the computed tomography (CT) scan, the angiography and the fluoroscopy. A commercially available CdZnTe (CZT) spectrometer with a lead collimator was employed for the measurement of scattered X-rays, which was performed in the usual manner.Results and Discussion: From the obtained energy spectra, the mean energies of the scattered X-rays lied between 40 and 60 keV. This also agreed with that obtained by the conventional half value layer method.Conclusion: The scattered X-rays to which medical workers may be exposed in the region around the eyes were characterized by means of spectrometry. The obtained mean energies of the scattered X-rays were found to match the flat region of the dosimeter response.
Delay Time of Propelling Force with Ship's Controllable Pitch Propeller(CPP)
Masayoshi Doi,Kazutoshi Nagamoto,Tetsuya Takehira,Yasuchika Mori 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
The purpose of this study is the identification of delay time of a design method that makes a controller for a system with a delay time in the case of a Controllable Pitch Propeller(CPP). A velocity response of CPPhas delay time until reaching the setting CPP"s angle and due to propeller"s slip. Especially, this study verifies the ship"s propelling force against the CPP"s angle and detects delay time by analyzing the data of the propelling force.
반지은,이현수,이대인,박환철,박재석,Yasutsugu Nagamoto,최종일,임홍의,박상원,김영훈 대한심장학회 2013 Korean Circulation Journal Vol.43 No.12
Background and Objectives: The electrophysiological properties associated with favorable outcome of radiofrequency catheter ablation (RFCA) for idiopathic ventricular arrhythmia (VA) originating from the papillary muscle (PM) remain unclear. The purpose of this study was to investigate the relationships of electrophysiological characteristics and predictors with the outcome of RFCA in patients with VAs originating from PM in the left ventricle (LV). Subjects and Methods: Twelve (4.2%) of 284 consecutive patients with idiopathic VAs originating from LV PM were assessed. The electrophysiological data were compared between the patients in the successful group and patients in the recurrence group after RFCA. Results: In 12 patients with PM VAs, non-sustained ventricular tachycardias (VTs, n=6), sustained VTs (n=4) and premature ventricular complexes (n=2) were identified as the presenting arrhythmias. Seven of eight patients showing high-amplitude discrete potentials at the ablation site had a successful outcome (85.7%), while the remaining four patients who showed low-amplitude fractionated potentials at the ablation site experienced VA recurrence. The mean duration from onset to peak downstroke (Δt) on the unipolar electrogram was significantly longer in the successful group than in the recurrence group (58±8 ms vs. 37±9 ms, p=0.04). A slow downstroke >50 ms of the initial Q wave on the unipolar electrogram at ablation sites was also significantly associated with successful outcome (85.7% vs. 25.0%,p=0.03). Conclusion: In PM VAs, the high-amplitude discrete potentials before QRS and slow downstroke of the initial Q wave on the unipolar electrogram at ablation sites were related to favorable outcome after RFCA.
Experimental studies on the aerodynamic performance of two box girders with side openings
Jiaqi Wang,Tomomi Yagi,Jun Ushioda,Kyohei Noguchi,Naoki Nagamoto,Hiroyuki Uchibori 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.2
A butterfly web girder is a box-shaped girder with discretely distributed side openings along the spanwise direction. Until now, there have been few studies related to the aerodynamic performance of the butterfly web bridge. The objective of the current study was to clarify the effects of the side openings on the aerodynamic performance of the girder. Two butterfly web girders with side ratios B/D = 3.24 and 5, where B is the girder width and D is the depth, were examined through a series of wind tunnel tests. A comparison of the results for butterfly web girders and conventional box girders of the same shape confirmed that the side openings stabilized the vortex-induced vibration and galloping when B/D = 3.24, whereas the vortex-induced vibration and torsional flutter were stabilized when B/D = 5. The change in the flow field due to the side openings contributed to the stabilization against the vibration. These findings not only confirmed the good aerodynamic performance of the butterfly web bridge but also provided a new method to stabilize the box girder against aerodynamic instabilities via discretely distributed side openings.
Kazuya Oshima,Motoki Iwasaki,Hironobu Sakaura,Takahito Fujimori,Yukitaka Nagamoto,Hideki Yoshikawa 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.1
Study Design: Prospective cohort study. Purpose: To identify differences in time-dependent perioperative changes between the Japanese Orthopaedic Association (JOA) score and the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) score in patients with cervical spondylotic myelopathy (CSM) and posterior longitudinal ligament (OPLL) who underwent cervical laminoplasty. Overview of Literature: The JOA score does not take into consideration patient satisfaction or quality of life. Accordingly, the JOACMEQ was designed in 2007 as a patient-centered assessment tool. Methods: We studied 21 patients who underwent cervical laminoplasty. We objectively evaluated the time-dependent changes in JOACMEQ scores and JOA scores for all patients before surgery and at 2 weeks, 3 months, 6 months, and 1 year after surgery. Results: The average total JOA score and the recovery rate improved significantly after surgery in both groups, with a slightly better recovery rate in the OPLL group. Cervical spine function improved significantly in the CSM group but not in the OPLL group. Upper- and lower-extremity functions were more stable in the CSM group than in the OPLL group. The effectiveness rate of the JOACMEQ for measuring quality of life was quite low in both groups. In both groups, the Spearman contingency coefficients were dispersed widely except for upper- and lower-extremity function. Conclusions: Scores for upper- and lower-extremity function on the JOACMEQ correlated well with JOA scores. Because the JOACMEQ can also assess cervical spine function and quality of life, factors that cannot be assessed by the JOA score alone, the JOACMEQ is a more comprehensive evaluation tool.