re-evaluation and modification of the St Thomas' Hospital (STH) classification to improve cochlear implantation outcomes. STUDY DEIGN: a prospective cohort study. children (n=20) between 2 to 8 years old who received a unilateral cochlear implant, all had difficult round window visibility and/or accessibility for electrode insertion. 10 had a round window insertion through the endoscopic assisted cochlear implantation and the remaining 10 had the same insertion using the retro-facial approach. THE SURGERY: two alternative techniques were used to overcome the difficult cases of round window electrode insertion: 1Endoscopic assisted cochlear implantation 2Transmastoid retro-facial approach RESULTS: both techniques proved to be effective and practical to overcome cases with difficult round window visibility and/or accessibility for electrode insertion. Round window insertion is associated with superior cochlear implantation outcomes, so we recommend a new modification to the STH classification to bypass the cochleostomy insertion.