Alterations of the retino-cortical conduction in patients affected by Classical Congenital Muscular Dystrophy (Cl-CMD) with merosin deficiency

Immunocytochemical analysis of the laminin alpha-2 (merosin) chain in the m uscle of patients with Classic Congenital Muscular Dystrophy (Cl-CMD) diffe rentiates the types of the disease associated with a merosin deficit from t hose that are merosin positive. Patients with Central Nervous System involv ement in merosin negative Cl-CMD always present alterations of the white ma tter at RMI, but usually these are not clinically significant. While ocular malformations (microphthalmia, alterations of the anterior chamber, of the retina, or of the angle and cataract) and damage to the Central Nervous Sy stem are described in some subtypes of CMD (Muscle Eye Brain disease, Walke r Warburg Syndrome), ocular involvement and retino-cortical conduction in m erosin negative Cl-CMD are not well known. This study reports on four patie nts affected by merosin negative Cl-CMD. All these patients presented impor tant alterations of the white matter associated with ventricular enlargemen t and, in one case, with pachygyria and micropolygyria. Refraction, visual acuity, ocular motility, anterior segment and fundus were examined. ERG Max imal, Cone and Rod response, VEP transient pattern reversal was carried out as well. Significant alterations at the standard ophthalmologic examinatio n or of the electroretinogram responses were not registered while, in all c ases, important modifications in retino cortical conduction (reduction in a mplitude, increase in latency, reduction in amplitude on the lateral deriva tions) were observed, demonstrating involvement of the optic pathway at dif ferent levels during the course of this disease.