Usher syndrome type 1: Early detection of electroretinographic changes

Abstract

Background Usher syndrome type 1 needs to be diagnosed at early age in order to timely manage speech therapy, cochlear implantation, and genetic counseling. Few data are available regarding electroretinographic testing before the age of six years. Aim To describe electroretinographic changes in young children with Usher syndrome type 1. Methods Retrospective study of fourteen patients. Age at first neurophysiologic testing was between 17 months and 5 years 4 months. Electroretinogram was performed using flash stimulation in mesopic conditions in the conscious child. Analysis was focused on the amplitudes and latencies of a- and b-waves. Results Whatever the age, an abnormal fundus was always confirmed with an absent electroretinogram. The youngest patient with absent electroretinogram was 17 month-old. When recorded on and after the 29th month of age, electroretinogram was absent in all cases, including 6 patients with normal fundus. In three patients a low-amplitude electroretinogram was present at first recording within the 26th and 27th months. Conclusion Electroretinogram showed retinopathy in young children with Usher syndrome type 1, even in the absence of fundoscopic signs of retinal degeneration.