Objectives:To determine the involvement of the midbrain and hindbrain (MHB) in the groups of classic (cLIS), variant (vLIS), and cobblestone complex (CBSC) lissencephalies and to determine whether a correlation exists between the cerebral malformation and the MHB abnormalities.Methods: MRI scans of 111 patients (aged 1 day to 32 years; mean 5 years 4 months) were retrospectively reviewed. After reviewing the brain involvement on MRI, the cases were reclassified according to known mutation (LIS1, DCX, ARX, VLDLR, RELN, MEB, WWS) or mutation phenotype (LIS1-P, DCX-P, RELN-P, ARX-P, VLDLR-P) determined on the basis of characteristic MRI features. Abnormalities in the MHB were then recorded. For each structure, a score was assigned, ranging from 0 (normal) to 3 (severely abnormal). The differences between defined groups and the correlation between the extent of brain agyria/pachygyria and MHB involvement were assessed using Kruskal-Wallis and 2 McNemar tests.
Results:There was a significant difference in MHB appearance among the three major groups of cLIS, vLIS, and CBSC. The overall score showed a severity gradient of MHB involvement: cLIS (0 or 1), vLIS (7), and CBSC (11 or 12). The extent of cerebral lissencephaly was significantly correlated with the severity of MHB abnormalities (p ϭ 0.0029).
Conclusion:
GLOSSARYA ϭ autosomal; ACC ϭ agenesis of corpus callosum; AD ϭ autosomal dominant; AP ϭ anteroposterior; AR ϭ autosomal recessive; CBL ϭ cerebellar; CBSC ϭ cobblestone complex; cLIS ϭ classic lissencephaly; CMD ϭ congenital muscular dystrophy; CSZ ϭ cell-sparse zone; DV ϭ dorsal-ventral; FCMD ϭ Fukuyama congenital muscular dystrophy; IVH ϭ inferior vermis hypoplasia; LV ϭ lateral ventricle; m ϭ medulla; M ϭ midbrain; MDS ϭ Miller-Dieker syndrome; MEB ϭ muscle-eyebrain; MHB ϭ midbrain and hindbrain; MR ϭ magnetic resonance; ND ϭ not determined; P ϭ pons; RC ϭ rostrocaudal; SCBH ϭ subcortical band heterotopia; SELH ϭ subependymal linear heterotopia; V ϭ vermis; vLIS ϭ variant lissencephaly; WI ϭ weighted image; WWS ϭ Walker-Warburg syndrome; XLD ϭ X-linked dominant; XLR ϭ X-linked recessive.The term lissencephaly (smooth outer brain surface) refers to a paucity of gyral and sulcal development. 1 It encompasses a spectrum of gyral malformations ranging from complete agyria to regional pachygyria and includes subcortical band heterotopia. Lissencephaly has been traditionally classified in two distinct groups: classic (cLIS, formerly called lissencephaly type 1) and cobblestone complex (CBSC, formerly called lissencephaly type 2) based on both brain imaging and pathology. To date, five genes have been identified as causing or contributing to human cLIS: LIS1, 14-3-3 in Miller-Dieker syndrome (MDS), DCX, RELN, and ARX. [1][2][3][4][5][6] A new classification has recently been proposed defining four groups of cLIS differing from each other by genetics and neuropathologic features of the cerebral cortex, cerebellum, and brainstem. 3 1)