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以磁振造影觀察腦幹之瓦勒氏退化
MR Imaging of Wallerian Degeneration in the Brain Stem
摘要
瓦勒氏退化(Wallerian degeneration)指神經細胞本身壞死，或其神經軸(axon)近端受到傷害時，其遠端的神經軸及髓鞘(myelin sheath)就逐漸溶解、破壞，這種退化現象可見於週邊神經，亦可見於中樞神經系統。 腦幹的瓦勒氏退化在磁振造影(MRI)中，可以觀察到不尋常的訊號改變，亦相當於皮質脊髓徑的部位上出現T1及T2弛緩時間(relaxation time)延長，且可能合併同側大腦脚(cerebral peduncle)及橋腦(pons)萎縮。 本文報告台中榮民總醫院從1989年元月至1991年4月間，在MRI檢查中，共發現18個腦幹有半邊萎縮的病例，回溯到運動皮質或放射冠都可找到陳舊性病灶，包括陳舊梗塞性中風7例，陳舊出血性中風3例，大腦半邊萎縮合併孔洞腦5例，大腦運動皮質區手術性破壞3例。因此可以診斷為腦幹的瓦勒氏退化。
並列摘要
Anterograde disintegration of axons and their myelin sheath, whether secondary to injury to the axon proximally or after death of its cell body, has been called Wallerian degeneration. It can be observed in not only peripheral nerve but also central nerve system. On MR imaging, Wallerian degeneration of the pyramidal tract can be demonstrated as an abnormal signal intensity, showing prolonged T1 and T2 relaxation times that correspond to the corticospinal tract, with or whithout shrinkage of the ipsilateral cerebral peduncle and pons. From January 1989 to April 1991, 18 patients were found to have atrophy of the brain stem demonstrated on MR imaging in Department of Radiology, VGH-Taichung. All these patients could be traced to have primary lesions in cerebral motor cortex or corona radiata. Seven cases had old infarction, 3 cases had old hemorrhagic CVA, 5 cases had cerebral hemiatrophy and porencephaly, and 3 cases had surgical damage.