Comparison of Insertion Depth and Hearing Preservation Results between HiFocus 1j and HiFocus Mid-Scala Electrodes in Pediatric Population

Background Various electrodes are available with a range of features and designs to fulfil anatomical and geometrical variations of the cochlea. The HiFocus 1j (1j) electrode developed by Advanced Bionics LLC is a lateral wall electrode designed to cover up to 1.5 turns or approximately 540° of the cochlea. The HiFocus Mid-Scala (HFms) was recently introduced and designed for structure preservation with a target insertion depth of 420°. Objective To evaluate the average insertion depth and variation, and to assess the potential for hearing preservation with 1j and HFms electrodes in children. Method A group of prelingually deafened children with regular anatomy who received the HiRes90K implant (either 1j or HFms electrode) underwent a plain radiography investigation shortly after the surgery to determine the angular insertion depth. The median age in each group was 3.6 years (1j) and 4.3 years (HFms). The amount of residual hearing was measured through audiometry prior surgery and then monitored at device activation and 1,3, 6, and 12 months later. Results Seventeen subjects were included for calculation of insertion depth. The median insertion depth and the variation for the 1j electrode was higher than for the HFms electrode (1j 476°; 443°–540°, HFms 413°; 390°–468°). Only eleven subjects were assessed for hearing preservation. Complete hearing preservation was achieved in seven subjects (five HFms and two 1j) and partial loss was observed in two subjects (one HFms and one 1j). Conclusion Both 1j and HFms electrodes are suitable for young children. Their flexible design allows round window insertions. The HFms group showed higher rates of hearing preservation (HP) than the 1j group.