Abstract: ［Abstract］〓Objective〖HTSS〗〓To analyze the clinical features and MRI characteristics of lissencephaly for its early diagnosis，treatment and prognosis judgment in clinical practice.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓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.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓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.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓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.

Key words: lissencephaly, signs and symptoms, magnetic resonance imaging