沃勒变性在中枢神经系统的MRI表现

目的 回顾沃勒变性及继发跨神经元退变的病理学改变,分析其在中枢神经系统的MRI表现。方法 根据沃勒变性的影像学标准,选择1995～1999年经MRI确诊的沃勒变性患者20例,年龄16～70岁,平均52岁。其中脑梗死11例,脑出血4例,创伤手术后2例,肿瘤术后1例,脑膜瘤1例,脑白质病1例。回顾性分析其MRI表现。结果 20例患者原发病灶均位于幕上,16例于原发病灶同侧出现条带样连续或不连续长T_1或等T_1、长T_2改变,位于皮质脊髓束通路。FLAIR及DWI扫描均显示高信号病灶。3例仅见原发灶同侧大脑脚萎缩,但未见异常信号。7例见局限性胼胝体萎缩,T_2加权像信号略显增高。2例患者出现交叉性小脑萎缩,示皮质脑桥小脑通路退变。结论 对中枢神经系统的沃勒变性和继发跨神经元退变描述的是分子水平的病理学变化,因变性是沿着已知的神经通路的、且存在特定信号改变,故MRI可在活体中对其进行观察和诊断。

MRI of Wallerian degeneration in central nervous system

Objective To review the pathologic changes of Wallerian degeneration (WD) and secondary transneuronal degeneration (TD) and evaluate their MRI in central nervous system. Methods Twenty patients aged 16-70 years (mean 52 years) definitely diagnosed WD by MRI during 1995-1999 according to the criterion of WD and TD were enrolled in this study. Their primary lesions were cerebral infarction (n=11), cerebral hemorrhage (n=4), after operation of intracranial trauma (n=2), after operation of neoplasm (n=1), meningioma (n=1) and demyelinating disease (n=1). their MRI were retrospectively analyzed. Results The primary focuses were located at supratentorium. MRI in 16 patients demonstrated a thin band-like long T| or isometric T1 and long T2 abnormal changes in corticospinal tract, continuous or discontinuous. Such changes showed high intensify signals on FLAIR and DWI. MRI in 3 patients showed only shrinkage of the ipsilateral cerebral peduncle but abnormal signal was not found. Regional atrophy of callosum with slightly increased signal intensity on T2 WI was found in 7 patients and crossed cerebellar atrophy indicating the degeneration in the corticopontocerebellar pathway were seen in 2 patients. Conclusion The WD and secondary TD of central nervous system are the terms describing pathological changes at molecular level. Such degenerations situate along the known neural pathways and exist specific signal characteristics. Thus it can be observed and diagnosed by MRI in vivo.