RESUMEN
HYPOTHESIS: To test whether there are significant differences in pediatric and adult temporal bone anatomy as related to cochlear implant (CI) surgery. BACKGROUND: Surgeons rely upon anatomic landmarks including the round window (RW) and facial recess (FR) to place CI electrodes within the scala tympani. Anecdotally, clinicians report differences in orientation of such structures in children versus adults. METHODS: Institutional review board approval was obtained. High-resolution computed tomographic scans of 24 pediatric patients (46 ears) and 20 adult patients (40 ears) were evaluated using software consisting of a model-based segmentation algorithm that automatically localizes and segments temporal bone anatomy (e.g., facial nerve, chorda tympani, external auditory canal [EAC], and cochlea). On these scans, angles pertinent anatomy were manually delineated and measured blinded as to the age of the patient. RESULTS: The EAC and FR were more parallel to the basal turn (BT) of the cochlea in children versus adults ([symbol in text] EAC:BT 20.55 degrees versus 24.28 degrees, p = 0.003; [symbol in text] FR:BT 5.15 degrees versus 6.88 degrees, p = 0.009). The RW was more closely aligned with the FR in children versus adults ([symbol in text] FR:RW 30.43 degrees versus 36.67 degrees, p = 0.009). Comparing the lateral portion of the EAC (using LatEAC as a marker) to the most medial portion (using [symbol in text] TM as a marker), the measured angle was 136.57 degrees in children and 172.20 degrees in adults (p < 0.001). CONCLUSION: There are significant differences in the temporal bone anatomy of children versus adults pertinent to CI electrode insertion.
Asunto(s)
Cóclea/anatomía & histología , Cóclea/crecimiento & desarrollo , Implantación Coclear/métodos , Implantes Cocleares , Oído Medio/anatomía & histología , Oído Medio/crecimiento & desarrollo , Adolescente , Adulto , Anciano , Envejecimiento , Niño , Preescolar , Cóclea/diagnóstico por imagen , Conducto Auditivo Externo/anatomía & histología , Conducto Auditivo Externo/crecimiento & desarrollo , Oído Medio/diagnóstico por imagen , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Lactante , Masculino , Persona de Mediana Edad , Procedimientos Quirúrgicos Otológicos , Ventana Redonda/anatomía & histología , Ventana Redonda/crecimiento & desarrollo , Tomografía Computarizada por Rayos X , Membrana Timpánica/anatomía & histología , Membrana Timpánica/crecimiento & desarrolloRESUMEN
The round window niche is a bony pouch of the tympanic cavity and clinically frequently explored, therefore its topography has fundamental impact on microsurgery. A total of 783 macerated and formalin-fixed temporal bones were used to study the normal anatomy of the round window and its development. The ossification of the niche starts in the 16th fetal week and is complete at birth. A process of the otic capsule, called the cartilage bar, forms the inferior wall of the round window niche. The anterior and superior walls of the niche form by intramembranous ossification, whereas the posterior and inferior walls predominantly form by enchondral ossification. The uneven growth of different walls of the round window niche can alter the shape of the entrance, which results in eight different types of niches: extremely narrow, descending tegmen, anterior septum, bony membrane, open fundus, exostosis, jugular dome and trabeculae.
Asunto(s)
Ventana Redonda/anatomía & histología , Ventana Redonda/crecimiento & desarrollo , Adolescente , Adulto , Anciano , Niño , Preescolar , Humanos , Lactante , Persona de Mediana Edad , Ventana Redonda/embriología , Ventana Redonda/cirugíaRESUMEN
A silicone impression method to study the anatomy of the round window region was used in 102 temporal bones belonging to individuals aged from 4 months of fetal life to 3-year-old children as well as adults. A total of 2,142 measurements of the round window, oval window and round window fossula was made in the molds. The data demonstrate that the round window shows a diameter from 1.21 mm (average for the short axis) to 1.74 mm (average for the long axis) and the circular shape was present in 55% of the adult temporal bones and in 18.18% of the fetal and infantile ones. The adult dimensions of the measured structures are reached during fetal development.