SOMATOSENSORY AND VISUAL-EVOKED POTENTIALS IN CONGENITAL MUSCULAR-DYSTROPHY - CORRELATION WITH MRI CHANGES AND MUSCLE MEROSIN STATUS

Congenital muscular dystrophy comprises a heterogeneous group of disor ders, that have in common an early onset and a dystrophic picture on t he muscle biopsy. The ''pure'' form of congenital muscular dystrophy i s not associated with severe mental retardation or structural changes in the brain, though white matter changes on brain imaging have been d etected in a significant proportion of cases. In this study we evaluat ed the incidence of sensory abnormalities (somatosensory and visual ev oked responses) in a group of 17 patients with ''pure'' congenital mus cular dystrophy and correlated the results of the evoked responses wit h the presence or absence of white matter changes on brain magnetic re sonance imaging. Our results show close correlation between the presen ce of MRI white matter changes and abnormalities in the sensory evoked potentials. Conversely, all patients with normal brain MRI had normal somatosensory evoked potentials (SEP). Visual evoked potentials were less sensitive than somatosensory evoked potentials in detecting abnor malities in children with white matter changes on MRT. With the recent discovery of deficiency in merosin expression in the skeletal muscle of a subgroup of patients with CMD, we also correlated the presence or absence of white matter changes and the SEP responses with the merosi n status. The results indicate that all merosin-negative patients had abnormal SEP as well as abnormal MRI, whilst no patient with normal me rosin expression had an abnormal scan or abnormal SEP. The study of ev oked potentials in CMD could therefore be of value not only for identi fying which patients are more likely to have white matter involvement, but also for subdividing different clinical groups within the CMD cat egory.