The purpose of this article is to report brain MRI findings of
merosin-negative congenital muscular dystrophy (CMD) in two cases and to discuss its differentiation from other CMD subtypes. The cases were investigated by 1.5 Tesla MRI equipment using T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR), 3D fast spoiled gradient recalled (SPGR) and post-contrast
gadolinium enhanced sequences and the diagnosis was confirmed by muscle biopsy with immunohistochemical staining for
merosin. Magnetic resonance imaging showed bilateral subcortical U-fibre white matter changes with periventricular sparing in the first case. Though this imaging finding is non-specific and could be seen in other
white matter diseases like
Canavan disease, the absence of other distinguishing MRI and clinical features of those conditions allowed a proper diagnosis. The second case showed diffuse subcortical and deep white matter involvement and cerebellar
cysts. There was no brainstem involvement,
polymicrogyria or
cobblestone lissencephaly in both of our cases which allowed differentiation of
merosin-negative CMD from other CMDs. Muscle biopsy in both these patients showed dystrophic changes with absent staining for
merosin confirming the diagnosis.
Merosin-negative CMD should be considered in the imaging differential diagnosis of
white matter diseases. In a patient presenting with features of CMD, MRI can be of help in further differentiation of the various CMD subtypes.