Randomized Controlled Trial Comparing Outcomes for Adult Cochlear Implant Recipients Using a Lateral Wall or Perimodiolar Electrode Array.

Objective: The primary aim of this study was to compare outcomes of adult cochlear implant recipients receiving either perimodiolar or lateral wall electrode arrays.

Study design: A prospective randomized controlled study was conducted to investigate final electrode array position, speech perception, and vestibular symptoms.

Setting: Tertiary referral center.

Patients: One hundred forty-four adults were assessed for the study. Inclusion criteria were bilateral postlingual severe to profound sensorineural hearing loss, with 500-Hz threshold in the implant ear of 75 dB HL or greater.

Interventions: Subjects were randomized to receive either perimodiolar or lateral wall electrode arrays.

Main outcome measures: Postoperative electrode array position was assessed by cone-beam computed tomography. Speech perception was measured preoperatively in best-aided conditions, and 3 and 12 months postoperatively. Vestibular symptoms were assessed using two self-reported questionnaires and/or clinician reports.

Results: Postoperative speech perception results for 124 implants in 123 adults showed significant improvement from preoperative scores and from 3 to 12 months postoperatively. Multiple regression analysis indicated no significant effect of electrode array position for any speech perception results at 3 and 12 months postoperatively. Auditory alone, monosyllabic word, and phoneme scores at 12 months were 48.4 and 71.4% for lateral wall electrode arrays and 49.8% and 72.0% for perimodiolar electrode arrays, respectively. No relationships between angle (depth) of electrode array insertion and speech perception outcomes were detected. There was no significant difference in incidence of vestibular symptoms between the groups.

Conclusions: Correct scala tympani placement of either the perimodiolar or lateral wall electrode arrays used in this study provides excellent speech perception outcomes, with no significant difference demonstrated between groups.