Cochlear implantation trough the middle cranial fossa : a novel approach to access the basal turn of the cochlea

Aline Gomes Bittencourt, Robinson Koji Tsuji, João Paulo Ratto Tempestini, Alfredo Luiz Jacomo, Ricardo Ferreira Bento, Rubens de Brito 1 Doctoral student in the Department of Otorhinolaryngology, Medical School, University of São Paulo, São Paulo, Brazil (Fellow in Otological and Skull Base Surgery at Hospital das Clínicas, University of São Paulo, São Paulo, Brazil). 2 PhD in Sciences (Associate Physician in the Department of Otorhinolaryngology, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil). 3 Medical student (Medical student, Medical School, University of São Paulo, São Paulo, Brazil). 4 Associate Professor (Professor in the Human Structural Topography Course at the Department of Surgery, Medical School, University of São Paulo, São Paulo, Brazil). 5 Associate Professor (Professor in the Otorhinolaryngology Course, Medical School, University of São Paulo, São Paulo, Brazil). 6 Associate Professor (Associate Professor in the Otorhinolaryngology Course, Medical School, University of São Paulo, São Paulo, Brazil). Federal University of São Paulo, São Paulo, Brazil. Send correspondence to: Aline Gomes Bittencourt. Departamento de Otorrinolaringologia, Hospital das Clínicas, Universidade de São Paulo. Av. Dr. Enéas de Carvalho Aguiar, no 255, 6o andar/sala 6167. São Paulo SP. Brazil. CEP: 05403-000. Tel/Fax: (11) 3088-0299. E-mail: [email protected] Paper submitted to the BJORL-SGP (Publishing Management System Brazilian Journal of Otorhinolaryngology) on November 27, 2011; and accepted on January 13, 2013. cod. 8925. The classic approach for cochlear implant surgery includes mastoidectomy and posterior tympanotomy. The middle cranial fossa approach is a proven alternative, but it has been used only sporadically and inconsistently in cochlear implantation. Objective: To describe a new approach to expose the basal turn of the cochlea in cochlear implant surgery through the middle cranial fossa. Method: Fifty temporal bones were dissected in this anatomic study of the temporal bone. Cochleostomies were performed through the middle cranial fossa approach in the most superficial portion of the basal turn of the cochlea, using the meatal plane and the superior petrous sinus as landmarks. The lateral wall of the internal acoustic canal was dissected after the petrous apex had been drilled and stripped. The dissected wall of the inner acoustic canal was followed longitudinally to the cochleostomy. Results: Only the superficial portion of the basal turn of the cochlea was opened in the fifty temporal bones included in this study. The exposure of the basal turn of the cochlea allowed the visualization of the scala tympani and the scala vestibuli, which enabled the array to be easily inserted through