Performance with the 20+2L lateral wall cochlear implant

Objective: The purpose of this study was to investigate the operating chara cteristics of the Nucleus 20 + 2L lateral wall cochlear implant including s peech recognition results. Study Design: This was a prospective randomized study involving five differ ent modes of stimulation. Setting: This study was carried out in an academic, tertiary referral cente r. Patients: The patients included in this study were adult cochlear implant c andidates ages 44-74 years. Length of deafness ranged from 1 to 58 years wi th a variety of etiologies. Interventions: All patients were implanted with a 20 + 2L implant, which in cludes an intrascalar electrode array and an apically placed extracochlear, titanium encased ball electrode in contact with the endosteum of the apica l turn. All patients underwent psychophysical and speech recognition testin g in five different modes of electrode configuration. Main Outcome Measure(s): The main outcome measures included thresholds, com fort levels, dynamic ranges, and speech recognition results obtained in fiv e electrode configuration modes. Results: Thresholds were significantly lower (repeated measures ANOVA) in b oth monopolar conditions when compared to bipolar mode of stimulation. A bi nomial statistical analysis indicated that in five of nine patients activat ed in all five modes of stimulation, the monopolar modes of stimulation res ulted in improved speech recognition scores. Conclusions: The results of the study demonstrate the feasibility of the us e of an apical lateral cochlear wall electrode in conjunction with an intra scalar electrode array. It further demonstrated the superiority of monopola r stimulation in selected patients.