New approach for cochlear implantation: Cochleostomy through the middle fossa

The middle fossa approach was used in 11 patients with profound bilateral h earing loss for insertion of a cochlear implant. Fibroadhesive otitis media (n = 1), bilateral cavity radical mastoidectomy (n = 1), autoimmune inner ear disease (n = 2), previous cranial trauma (n = 1), genetic prelingual de afness (n = 5), and otosclerosis (n = 1) were the causes of deafness. A coc hleostomy was performed on the most superficial part of the basal turn, and the electrode array was inserted up to the cochlear apex. Speech perceptio n tests (1-9 months after cochlear implant activation) yielded better resul ts in these patients compared with a homogeneous group of postlingually dea f patients operated on through the traditional transmastoid route. Insertio n of the implant through the middle fossa cochleostomy furnishes the possib ility of stimulating areas of the cochlea (ie, the middle and apical turns) where a greater survival rate of spiral ganglion cells is known to occur, with improvement of information regarding the formants relevant for speech perception.