[Cochlear implant in patients with congenital malformation of the inner ear]

To summarize the clinical experience with multi-channel cochlear implantation in patients with inner ear malformations and evaluate and the outcomes of speech rehabilitation.

A retrospective study was conducted in 295 patients receiving cochlear implantation from 1998 to 2007, including 25 patients with large vestibular aqueduct syndrome (LVAS), 9 with Modini malformation, and 5 with common cavity deformity. All the patients received the Nucleus24 cochlear implants. In LVAS cases, 4 had Nucleus 24R (ST) implants, 8 had Contuor implants, 10 had Contuor Advance, and the remaining cases used Nucleus24(M) straight-electrode implants.

Severe gusher appeared in 3 cases of LVAS, and perilymph fluctuation were seen in other 15 cases. Four patients with Mondini malformation and 2 with common cavity malformation also experienced severe gusher, but the electrodes were inserted smoothly in all the patients without postoperative facial paralysis or cerebrospinal fluid leakage. The hearing threshold in these patients was similar to that in patients with normal cochlear structure. After speech rehabilitation for over 6 months, the abilities of speech discrimination and spoken language improved in all the cases in comparison with the preoperative lingual functions.

Multi-channel cochlear implantation can be performed in patients with inner ear malformation, but should not be attempted in patients with poor cochlear and cochlear nerve development. A comprehensive pre-operative radiographic and audiological evaluation is essential.