Estudo anatômico da cóclea para confecção de instrumental para a cirurgia de implante coclear com 2 feixes de eletrodos em cócleas ossificadas / Cochlear anatomy study used to design surgical instruments for cochlear implants with two bundles of electrodes in ossified cochleas

A ossificação da cóclea, decorrente principalmente de meningite, impede a inserção completa do implante coclear convencional. Os implantes com 2 feixes de eletrodos mais curtos do que o convencional foram desenvolvidos especialmente para cócleas ossificadas. Porém, durante essa cirurgia há um grande risco de lesão da artéria carótida interna (ACI). Portanto, a medida da profundidade das cocleostomias para inserir os dois feixes de eletrodos aumentaria a segurança desse procedimento. OBJETIVOS: 1) Obter as distâncias entre as cocleostomias e a ACI em ossos temporais de cadáver; 2) Confeccionar instrumento que possa ser usado na cirurgia de implante coclear com 2 feixes de eletrodos. FORMA DE ESTUDO: Experimental prospectivo. MATERIAL E MÉTODO: Em 21 ossos de cadáveres foi realizada: 1) mastoidectomia cavidade aberta; 2) cocleostomias nos giros basal e médio da cóclea; 3) identificação da ACI; 4) medida da distância entre as cocleostomias e a artéria. RESULTADOS: A medida média ± desvio padrão obtida para o túnel superior foi 8,2 ± 1,1mm e para o túnel inferior foi 8,1± 1,3mm. A menor distância encontrada foi 6,5mm para o túnel superior e 6,0mm para o túnel inferior. CONCLUSÃO: Apesar dos parâmetros calculados concluímos que a melhor medida para ser considerada na confecção do instrumento cirúrgico serão as mínimas medidas obtidas em cada um dos giros cocleares, pois é a maneira mais segura para evitar a lesão da ACI, que pode ser fatal.

Cochlear ossification, mainly secondary to meningitis, prevents the complete conventional cochlear implant insertion. Implants with two electrode bundles shorter than the conventional ones were specifically developed for ossified cochleas. However, during surgery there is a high risk of damaging the internal carotid artery (ICA). Therefore, measuring cochleostomy depth in order to insert the two electrode bundles would greatly increase the procedure's safety. AIMS: 1) Find the distances between cochleostomies and ICA in cadaver temporal bones. 2) Design an instrument that can be used in cochlear implant surgery to introduce an implant with two bundles of electrodes. STUDY DESIGN: Experimental prospective. MATERIALS AND METHODS: In 21 temporal bones from cadavers we performed: 1) canal wall down mastoidectomy; 2) cochleostomy in the cochlear basal and middle turns; 3) ICA identification; 4) Length determination between the cochleostomies and the artery. RESULTS: the average distance ± standard deviation obtained for the upper tunnel was of 8.2 ± 1.1 mm and for the lower tunnel it was of 8.1± 1.3 mm. The shortest distance found was of 6.5 mm for the upper tunnel and 6.0 mm for the lower tunnel. CONCLUSION: Despite the values calculated, we concluded that the best value to be considered in creating a surgical instrument are the minimum lengths obtained for each one of the cochlear turns, because this is the safest way to avoid damaging the ICA, that can be fatal.

Pediatric cochlear implantation: experience in Thai patients.

OBJECTIVE: This study was to evaluate the result of cochlear implantation in Thai pediatric patients from 1999-2003. DESIGN: A prospective, open-labeled study. SETTING: University teaching hospital. MATERIAL AND METHOD: Long term surgical and audiologic results comparison after cochlear implantation in 2 cases with Mondini anomality, 7 normal cochlea cases and a case of post meningitis post lingual child. MAIN OUTCOME MEASURES: Speech perception tests battery. RESULTS: Among 10 children, 8 were implanted with Nucleus 22/24; the other two were implanted with Med-el device system. The pre-operated cochlea in 2 cases showed Mondini deformity; both had gushers during the operation with a good outcome. The other 8 cases had normal cochlea although one was deaf from bacterial meningitis. There were 3 re-implantations. Speech production and perception was improved faster in the two children implanted with Med-el than those implanted with Nucleus devices. CONCLUSION: Cochlear implantation in Mondini cases can be successful in speech production and perception. Speech perception ability depended on the age of implantation and preoperative rehabilitation.

A displasia de Mondini / The Mondini dysplasia

Os autores apresentam e discutem alguns aspectos histológicos e fisiopatológicos da Displasia de Mondini e as possibilidades diagnósticas e terapêuticas atuais