Inclusion Criteria:  Bilateral severe-to-profound sensorineural hearing loss who received cochlear implantation. Bilateral or unilateral enlarged vestibular aqueduct (EVA) with or without Mondini malformation (IP-II) on temporal bone computed tomography (CT) and/or magnetic resonance imaging (MRI).  Exclusion Criteria:  Hearing loss that is associated with symptoms which meet the criteria of already known syndromes. With other type of inner ear malformation.