Merosin-deficient congenital muscular dystrophy: the spectrum of brain involvement on magnetic resonance imaging

Children with merosin-deficient congenital muscular dystrophy (CMD) have st riking white matter changes on T-2 weighted brain magnetic resonance imagin g (MRI). There have been occasional cases with structural abnormalities, ma inly involving the occipital cortex. We report our brain imaging findings i n 14 children with merosin-deficient CMD. Ten cases had a severe reduction or absence of merosin on immunocytochemistry and four cases had partial red uction. All 14 cases had white matter changes, which appeared after the fir st 6 months of life and persisted with time. The changes were diffuse and t he oldest child scanned (14 years) also showed involvement of the U fibres. Five children with total absence of merosin also had structural abnormalit ies. One child had moderate menial retardation and epilepsy, mainly charact erised by complex partial seizures, with atypical absences, which had been difficult to treat. Brain MRI showed marked occipital agyria and pontocereb ellar hypoplasia. The gyral pattern of the rest of the brain looked normal. The four other cases, all with normal intelligence, also had cerebellar hy poplasia with variable involvement of the pens. They did not, however, have neuronal migration defects. It is recognised that several forms of congeni tal muscular dystrophy, namely Fukuyama CMD, muscle-eye-brain disease and W alker-Warburg syndrome, have structural brain abnormalities and associated severe mental retardation. Our cases demonstrate that a range of structural malformations can also be found in a significant number of children with m erosin-deficient CMD. (C) 1999 Elsevier Science B.V. All rights reserved.