[Cochlear implantation in patients with inner ear malformations, clinical analysis of 25 cases]

To explore the clinical experience of multi-channel cochlear implantation in patients with bilateral inner ear malformations.

Multi-channel cochlear implantation was conducted among 180 patients from 1997 to 2001. Twenty-five of them, being with inner ear malformations, were given hearing and speech rehabilitation including sound detection, word discrimination, auditory comprehension and spoken language skill development. A follow-up lasting 4 - 24 months was conducted after the operation. A retrospective analysis was performed among these 25 patients to observe the surgical outcomes and mapping characteristics after surgery.

(1) All patients restored their auditory sensations after the operation. (2) Stapedial gusher was found in 13 cases with inner ear malformations, especially those with Mondini malformation, much more frequently than among the patients with other malformations. (3) Most of the action electrodes were inserted in the "cochleostomy" in full length, only 2 pairs of them remained outside of the "cochleostomy". (4) No serious complications occurred after implantation. (5) The impedance of the electrodes, T level and C level were higher in the 25 cases than in the normal cochlear implantation, however, with the hearing similar hearing threshold. (6) After training, the abilities of speech discrimination and spoken language were improved in comparison with those before operation.

The cochlear implantation can be performed safely in patients with bilateral inner ear malformations. The primary outcome of cochlear implantation in hearing rehabilitation is similar for both the patients with inner ear malformations and those with normal cochlear structure.