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Performance with the 20 + 2L lateral wall cochlear implant
P R Kileny1, T A Zwolan, S A Telian
1Department of Otolaryngology, University of Michigan Medical School, Ann Arbor 48109-0312, USA.
Objective:
The purpose of this study was to investigate the operating characteristics of the Nucleus 20 + 2L lateral wall cochlear implant including speech recognition results.
Study Design:
This was a prospective randomized study involving five different modes of stimulation.
Setting:
This study was carried out in an academic, tertiary referral center.
Patients:
The patients included in this study were adult cochlear implant candidates ages 44-74 years. Length of deafness ranged from 1 to 58 years with a variety of etiologies.
Interventions:
All patients were implanted with a 20 + 2L implant, which includes an intrascalar electrode array and an apically placed extracochlear, titanium encased ball electrode in contact with the endosteum of the apical turn. All patients underwent psychophysical and speech recognition testing in five different modes of electrode configuration.
Main Outcome Measure(S):
The main outcome measures included thresholds, comfort levels, dynamic ranges, and speech recognition results obtained in five electrode configuration modes.
Results:
Thresholds were significantly lower (repeated measures ANOVA) in both monopolar conditions when compared to bipolar mode of stimulation. A binomial statistical analysis indicated that in five of nine patients activated in all five modes of stimulation, the monopolar modes of stimulation resulted in improved speech recognition scores.
Conclusions:
The results of the study demonstrate the feasibility of the use of an apical lateral cochlear wall electrode in conjunction with an intrascalar electrode array. It further demonstrated the superiority of monopolar stimulation in selected patients.