ABSTRACT
Objective To study the influence of noise under normal and high pressure environment on the cochlea, so as to make up for the defect caused by the lack of testing means to study the noise effect on behavioral characteristics of cochlear hearing by using numerical simulation method. Methods Based on CT scan images of healthy cochlea, and combined with self-programming, the three-dimensional finite element model of the cochlear spiral was established by using PATRAN software. Analysis on flow solid coupling frequency response and transient response was conducted by using NASTRAN software, and the impact of noise under normal and high pressure environment on the cochlea was numerically simulated. Results The calculated results were in agreement with the experimental results reported in the literature, which verified the correctness of the model. When the frequency was lower than 5 kHz, the basement membrane displacement by noise excitation under normal and high pressure environment was basically the same; when the frequency was higher than 5 kHz, the basement displacement by noise excitation under normal environment decreased gradually. Conclusions Under high pressure environment, the high-frequency noise shows a more obvious effect on the basilar membrane. The numerical simulation results can make up for the deficiency in studies about noise effect on characteristics of human cochlear hearing due to the lack of experimental methods, and provide new ideas and theoretical support for targeted experimental study of the cochlea in the future.
ABSTRACT
Objective To study the influence of noise under normal and high pressure environment on the cochlea,so as to make up for the defect caused by the lack of testing means to study the noise effect on behavioral characteristics of cochlear hearing by using numerical simulation method.Methods Based on CT scan images of healthy cochlea,and combined with self-programming,the three-dimensional finite element model of the cochlear spiral was established by using PATRAN software.Analysis on flow solid coupling frequency response and transient response was conducted by using NASTRAN software,and the impact of noise under normal and high pressure environment on the cochlea was numerically simulated.Results The calculated results were in agreement with the experimental results reported in the literature,which verified the correctness of the model.When the frequency was lower than 5 kHz,the basement membrane displacement by noise excitation under normal and high pressure environment was basically the same;when the frequency was higher than 5 kHz,the basement displacement by noise excitation under normal environment decreased gradually.Conclusions Under high pressure environment,the high-frequency noise shows a more obvious effect on the basilar membrane.The numerical simulation results can make up for the deficiency in studies about noise effect on characteristics of human cochlear hearing due to the lack of experimental methods,and provide new ideas and theoretical support for targeted experimental study of the cochlea in the future.
ABSTRACT
Objective To study the influence of noise under normal and high pressure environment on the cochlea,so as to make up for the defect caused by the lack of testing means to study the noise effect on behavioral characteristics of cochlear hearing by using numerical simulation method.Methods Based on CT scan images of healthy cochlea,and combined with self-programming,the three-dimensional finite element model of the cochlear spiral was established by using PATRAN software.Analysis on flow solid coupling frequency response and transient response was conducted by using NASTRAN software,and the impact of noise under normal and high pressure environment on the cochlea was numerically simulated.Results The calculated results were in agreement with the experimental results reported in the literature,which verified the correctness of the model.When the frequency was lower than 5 kHz,the basement membrane displacement by noise excitation under normal and high pressure environment was basically the same;when the frequency was higher than 5 kHz,the basement displacement by noise excitation under normal environment decreased gradually.Conclusions Under high pressure environment,the high-frequency noise shows a more obvious effect on the basilar membrane.The numerical simulation results can make up for the deficiency in studies about noise effect on characteristics of human cochlear hearing due to the lack of experimental methods,and provide new ideas and theoretical support for targeted experimental study of the cochlea in the future.
ABSTRACT
<p><b>OBJECTIVE</b>To review our experience in surgical management of proximal anterior cerebral artery (A1) aneurysms in 23 patients.</p><p><b>METHODS</b>Between January, 2004 and December, 2014, 23 patients (1.6%) with A1 aneurysms diagnosed by CTA or DSA were treated surgically. The "3H" therapy was adopted for postoperative prevention of cerebrovascular spasm. All the patients were followed up and examined with cerebrovascular CTA at 6, 12, 48 and 60 months after the operation with their Glasgow Outcome Scale score recorded.</p><p><b>RESULTS</b>The patients consisted of 15 men and 8 women with an age range of 16 to 72 years (mean 51.3 years). The average diameter of the aneurysms was 5.8 mm, ranging from 3.2 to 9.7 mm. Twenty-two saccular aneurysms were found in these patients; 21 patients presented with SAH and two had vascular malformation. All the A1 aneurysms were managed through the pterional approach, and the mean postoperative Glasgow Outcome Scale score was 4.8.</p><p><b>CONCLUSION</b>Thorough analysis of the angiographic data is essential for the diagnosis and treatment of A1 aneurysms. Preservation of the perforators and prevention of aneurysm rupture are critical during the surgery. Full exposure of the Sylvian fissure and temporary occlusion of the parent artery ensures safe and effective dissection of A1 aneurysms.</p>