Cochlear implantation and audiological findings in a child with Zellweger spectrum disorder

Peroxisome Biogenesis Disorders in the Zellweger Spectrum (PBD-ZSD) are autosomal recessive disorders characterized by defects in functional peroxisomes. Clinical manifestations can range in severity and age at presentation and often include retinitis pigmentosa, neuroregression, and peripheral neuropathy. Although hearing loss is often associated with PBD-ZSD, the site of lesion is poorly understood. This study reports our experience with a child with a moderate form of PBD-ZSD who underwent successful bilateral cochlear implantation for progressive severe-to-profound hearing loss and performs well with the device. The audiological profile was characterized by severe sensorineural hearing loss bilaterally on auditory brainstem responses, reduced cochlear microphonic potentials with absent compound action potential and summating potential on electrocochleography, and clear neural responses on cochlear implant-evoked, electrical compound action potential testing after implantation. These findings suggest a cochlear-neural site of lesion rather than a true auditory neuropathy.