MRI对脑梗死继发皮质脊髓束华勒变性的动态研究

Dynamic Study of Corticospinal Tract Wallerian Degeneration After Cerebral Infarction with MRI

目的利用MRI观察脑梗死继发皮质脊髓束华勒变性的变化规律,探讨早期华勒变性扩散加权成像（DWI）信号特点与预后的关系,为临床认识华勒变性提供影像学依据。资料与方法回顾性分析30例大脑中动脉、颈内动脉狭窄闭塞致脑梗死患者,依据脑梗死后所致皮质脊髓束变性DWI呈高信号和等信号分为两组,所有患者于发病后1 d、1个月、6个月、12个月均行常规MRI及DWI检查,测量患侧与健侧大脑脚宽度比,采用美国国立卫生研究院卒中量表（NIHSS）评估病情严重程度,比较两组大脑脚宽度比及NIHSS评分。结果随访1个月、6个月、12个月,急性期皮质脊髓束华勒变性DWI高信号组NIHSS评分均高于等信号组,差异有统计学意义（P〈0.01）,两组发病后1 d NIHSS评分差异无统计学意义（P〉0.05）。随访12个月,急性期皮质脊髓束华勒变性DWI高信号组患侧大脑脚宽度比小于等信号组,差异有统计学意义（P〈0.05）,DWI高信号组大脑脚萎缩更明显;两组发病后1 d、随访1个月、6个月患侧大脑脚宽度比差异无统计学意义（P〉0.05）。结论皮质脊髓束华勒变性1~6个月以轴突肿胀、髓鞘崩解、T2WI高信号为特征,6~12个月以有髓纤维容积减少、脑干不对称萎缩、胶质增生为特征。皮质脊髓束华勒变性DWI早期高信号提示预后较差。

Purpose To discuss the relationship between the features of early corticospinal tract（CST） Wallerian degeneration（WD） signals in DWI and its prognosis by observing characteristics of CST WD after cerebral infarction with MRI.This will provide imaging basis for a better clinical understanding in CST WD.Materials and Methods In this retrospective study,we assessed images and clinic data for 30 patients with acute middle cerebral/internal carotid artery stroke,and divided them into CST hyperintensity group and isointensity group in DWI at day 1.Then all the patients underwent MRI and DWI examinations at day 1,30,180,and 360 after stroke onset.The ratio of the cross-sectional width of the ipsilateral cerebral peduncle to the width of the contralateral cerebral peduncle were measured and the severity of dysfunction patients were assessed according to national institute of health stroke scale（NIHSS）.The NIHSS scores and cerebral peduncle width ratio were compared between the two groups.Results The NIHSS scores were statistically higher in CST DWI hyperintensity group than in the isointensity group at day 30,180,360（P0.01）,but there were no statistical differences in the NIHSS scores at day 1 between the two groups（P0.05）.The cerebral peduncle width ratio was significantly lower in CST DWI hyperintensity at acute stage compared with that in the isointensity group only at day 360（P0.05）,and the cerebral peduncle atrophy was more obvious in the DWI hyperintensity group;there were no statistically differences in the cerebral peduncle width ratio at day 1,30,and 180 between the two groups（P0.05）.Conclusion The corticospinal tract WD is characterized by axonal swelling,breakdown of myelin sheath and hyperintense on T2-weighted MRI during 1 to 6 months;and during 6 to 12 months,it is characterized by volume loss of myelinated fibres,unilateral brainstem atrophy and gliosis on MRI.At the same time,the hyperintense on DWI predicts unsatisfactory prognosis in corticospinal tract WD poststroke onset.