To evaluate long-term stability and residual hearing preservation after cochlear implantation with electric acoustic stimulation (EAS).
Long- and short-term hearing preservation (HP) of 18 EAS subjects (21 ears) was evaluated. Short-term was defined as follow-ups less than 12 months after surgery versus long-term outcomes longer than 12 months postsurgery.
Mean period of observation in the short-term group was 4 ± 3.0 months (range 0–7). In the long-term group the mean follow-up was 28.4 ± 15.0 months (range 12–58). Full insertion was possible in all 18 implanted subjects. In the short-term group, complete HP was achieved in 50%, partial HP in 33.3%, and minimal HP in 8.3% of the investigated subjects. One subject lost hearing completely. In the long-term group, complete HP was achieved in 50%, partial HP was observed in 40%, and minimal HP in 10% of the ears. No subject lost hearing completely. Subjects using EAS showed better word recognition scores after surgery (mean at 65 dB 55.3 ± 18.4; mean at 80 dB 68.1 ± 12.2) than subjects using electric stimulation only (mean at 65 dB 38.3 ± 18.1; mean at 80 dB 60.0 ± 16.4) with nonfunctional low-frequency hearing.
The study confirms that hearing can be preserved to a large extent. As a result, most subjects benefitted from EAS. Subjects with postoperative functional low-frequency hearing showed greater benefit in word speech tests. Furthermore, the outcomes show that EAS implantation is a safe, effective, and most importantly stable treatment option (longest follow-up with 58 mo).