Hearing Preservation With the Use of Flex20 and Flex24 Electrodes in Patients With Partial Deafness

To evaluate the impact of electrode length on hearing preservation (HP) in Partial Deafness Treatment-Electrical Complement (PDT-EC) subjects.

Retrospective case review.

Tertiary referral center.

Twenty-three PDT-EC patients (with preoperative air-conduction thresholds ≤30 dB up to 500 Hz) were divided into two groups: Flex20 electrode (Med-EL GmbH, Innsbruck, Austria) (12 patients) and Flex24 electrode (Med-EL GmbH, Innsbruck, Austria) (11 patients).

All participants were subjected to minimally invasive cochlear implantation using the round window approach.

Pure tone audiometry (125-8000 Hz) was performed preoperatively and at 1, 6, 12, and 24 months postoperatively. HP was established using the HEARRING group formula. Speech understanding was assessed preoperatively and at 12 and 24 months postoperatively.

Analysis of HP for every individual indicates that more than half the patients with Flex20 and Flex24 had complete HP at 6 months follow-up. None of the patients from either group had complete loss of hearing. At activation, average air-conduction thresholds for low frequencies (125-500 Hz) were slightly better for the short electrode (M = 29.03) than for the long (M = 39.10) but the difference was not statistically significant (p = 0.067). The effect of electrode (Flex20 versus Flex24) was not significant in terms of pure tone audiometry and speech recognition at long-term follow-up.

In the early postoperative period, complete HP was possible in a majority of patients from both groups, but slightly better HP outcomes were achieved by Flex20. In the long term, the length of the electrodes does not affect the degree of HP or speech understanding.