Merosin-positive congenital muscular dystrophy, white matter abnormalities, and bilateral posterior occipital cortical dysplasia.

Abstract

Congenital muscular dystrophy (CMD) is one of the most frequent dystrophies of childhood, which is commonly characterized by neonatal muscle impairment with or without clinical evidence of central nervous system involvement. CMDs were classified into five clinically distinct forms: the two classical CMDs with and without deficit of the a2 laminin chain (merosin) caused by mutations on chromosome 6q2, the Fukuyama CMD (severe form, initially described in Japanese patients and recently linked to the chromosome 9q31-33), Walker-Warburg syndrome and the muscle-eye-brain disease described in Finnish patients. The majority of these forms have severe clinical and imagiological involvement of SNC. This aspect is rarely observed on classical CMD, particularly in the merosin-positive form. We describe a case of a 28 year-old woman, with clinical and histopathological signs of classical CMD merosin-positive (no deficient), without mental retardation, but with epilepsy. MRI T2 weighted images, revealed diffuse and symetrical high signal white matter of both cerebral hemispheres, affecting corpos calosum, posterior arms of internal capsules and the piramidal tract to mesencephalon. It also disclosed diffuse and symetrical high signal of basal ganglia, specially, the head of caudate nuclei. These were associated with bilateral occipital posterior cortical dysplasia. The observed imagiological pattern could represent a new subtype of CMD, hybrid between classical CMD and the severe forms, however it is not clear where it fits in the spectrum. This case denotes the possible envolvement of SNC in patients merosin-positives. Based on this findings we suggest doing MRI scans to all patients with CMD no deficient in merosin.