Electroretinogram assessment of children with sensorineural hearing loss: implications for screening

BACKGROUND The guidelines of the National Deaf Children's Society recommend that children with sensorineural hearing loss (SNHL) be routinely screened for ophthalmological problems and suggest electroretinography (ERG) to exclude Usher syndrome. The present study reports the nature and prevalence of abnormal ERG findings in a cohort of children with SNHL undergoing ERG with the aim of identifying risk factors for the diagnosis of Usher syndrome. METHODS The medical records of children (<18 years of age) with SNHL referred for ERG at Moorfields Eye Hospital, London, between January 2009 and December 2011 were retrospectively reviewed. Patients were included if they had been referred with SNHL by an audiological medicine consultant and the primary indication for electrodiagnostic testing was possible Usher syndrome. RESULTS A total of 84 cases met inclusion criteria of which 13 (15%) had ERG findings showing rodcone dysfunction consistent with a diagnosis of Usher syndrome. Two patients with retinal pigmentary changes had normal ERGs and were diagnosed with rubella retinopathy based on the clinical findings. Risk factor analysis showed that age of years at the time of ERG, sex, and bilateral hearing loss were not predictive of a diagnosis of Usher syndrome. However, the presence of or referral for cochlear implants, having relevant symptoms and/or clinical signs consistent with a retinal dystrophy, and profound hearing loss were all highly predictive. CONCLUSIONS ERG is a useful diagnostic tool in children with SNHL and should be performed in children with SNHL who have cochlear implants and/or have signs or symptoms of retinal dystrophy. A focused approach could have potential cost-saving benefit.