光滑脑的MRI表现及其分级

MRI appearances and grades of lissencephaly

目的分析光滑脑的临床表现及MRI表现,为早期诊断和治疗提供参考依据。方法回顾性分析20例光滑脑的临床表现及MRI表现,同时进行MRI分级。结果光滑脑包括无脑回、巨脑回及皮层下带状灰质异位,20例光滑脑临床表现为不同程度的运动障碍、精神发育迟滞,癫痫6例,小头畸形2例。无脑回MRI表现为正常的脑沟脑回消失,脑皮层增厚(>10mm),脑白质减少,大脑半球呈"8"字形;巨脑回表现为脑回增宽,脑皮层增厚,脑白质减少,灰白质交界清楚;皮层下灰质异位又称为双皮层,在侧脑室侧脑白质和脑皮质之间出现一层带状异位的灰质,呈双侧对称分布,MRI图像显示从侧脑室到脑皮质表面出现4层结构:(1)正常脑室周围脑白质;(2)异位的脑灰质层;(3)一薄层皮层下脑白质;(4)正常的皮层灰质。按照Dobyns等的分级,光滑脑1级1例,2级2例,3级1例,4级12例,5级3例,6级1例。MRI分级与临床严重程度存在密切关系。结论光滑脑是一种严重神经元移行障碍,MRI表现及其分级结合临床表现可为早期诊断、治疗及预后判断提供重要参考。

Objective To analyze the clinical features and MRI characteristics of lissencephaly for its early diagnosis,treatment and prognosis judgment in clinical practice.Methods The clinical symptoms and signs and the findings in magnetic resonance imaging(MRI)of 20 cases of lissencephaly were investigated retrospectively.Its severity in MRI finding was graded.Results The spectrum of lissencephaly ranges from absent(agyria)or decreased(pachygyria)convolutions to less severe malformation known as subcortical band heterotopia.Of twenty patients,The clinical features were mainly manifested as mental retardation(twenty patients),and motor retardation(twenty patients),and epilepsy(six patients).In terms of MRI features,agyria displayed cerebral surface smooth,hourglass of cerebral contour,increased cortical gray and relatively small amount of white matter,while pachygyria displayed broad,flat gyri with thickened cortex,and reduced white matter,smooth border between the gray and white matter.subcortical band heterotopias displayed the characteristic isointensity of the heterotopic band with the cortex in all imaging sequences between the normal white matter and cortex gray.According to the Dobyns′graded,1 case in grade 1,2 cases in grade 2,1 case in grade 3,12 cases in grade 4,3 cases in grade 5,1 case in grade 6.Severity of clinical finding correlates well with the degree of lissencephaly.Conclusion Lissencephaly is a brain malformation caused by neuronal migration abnormality.The characteristics of MRI along with clinical findings could provide important evidence for early diagnosis,timely treatment and prognosis judgment of lissencephaly.