| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 102 === Diabetes mellitus is one of the most common diseases in the world and can cause many types of neuropathies, and even mortality. It is therefore important to understand how diabetes mellitus alters the mechanical properties of nerve tissues and their blood vessels. This study is to examine the dilatation of vasa nervorum inside the nerve trunk by using circular compression test and Doppler OCT, then proposes a biomechanical model to explain how vasa nervorum interact with the compression force and compare the simulated results with images captured by Doppler OCT. In this study, in situ compression-and-hold circular compression tests were applied to the sciatic nerves of both diabetic rats and normal rats. Doppler optical coherence tomography (Doppler OCT) was then utilized to monitor the configuration of the vasa nervorum in two groups of rats. The force data acquired in the compression tests were fitted by using Fung’s quasi-linear viscoelastic model (QLV) to determine the viscoelasticity of the nerves. The results show that the nerves in the diabetic group had a longer relaxation time but lower stress responses than those in the normal group. Consequently, the Doppler OCT observations reveal that in contrast to the normal vasa nervorum, the diabetic vasa nervorum did not dilate in the relaxation phase. This study also provides that the biomechanical properties of vasa nervorum may be described as shell model and confirms the autoregulatory responses of blood vessels. In summary, the diabetic nerve is friable and its vasa nerverom is fragile and may explain why the diabetic patients are more prone to carpal tunnel syndrome.
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