New aspects in the histopathology of the cochlear aqueduct in children

Objective: To study the histoanatomy and pattern of growth of the cochlear aqueduct in children of different ages. Background: Since Du Verney described the cochlear aqueduct in 1684, its fo rm, pattern of growth, patency, and function have been controversial. As mo st of the previous studies of the aqueduct were performed on adults, none h ad looked at its pattern of growth from the neonate to 9 years of age. In a ddition, previous histologic studies had suggested an age-dependent patency , but recent investigations had not statistically correlated patency with a ge. Method: Histologic sections of 137 temporal bones from 79 infants and child ren were studied by light microscopy. From this: group, we selected 32 temp oral bones from 18 infants, newborn to 9 years (average age 9.1 months, med ian 0.5 months),in whom the entire length of the cochlear aqueduct was visi ble on one histologic section. We measured the width of the orifices at the scala tympani (external aperture) and the subarachnoid space (internal ape rture) and the length of the aqueduct, and noted the contents of the lumen. Results: The measurements of the cochlear aqueduct were: length 4.19 mm (ra nge 1.7-10.7 mm), width of the external aperture 435 mu m (range 225-869 mu m). width of the internal aperture 1,323 pm (range 699-2344 mu m), mean di ameter of the narrowest part (isthmus) 138 pm (range 68-244 mu m), intralum inal mononucleated cells 6%, and erythrocytes 15%. Conclusions: Our findings demonstrate that, in the newborn, the cochlear aq ueduct is short and patent. After birth, the duct lengthens significantly p rimarily by growth of the medial periosteal portion. There was no statistic ally significant change in the diameter of the external and internal apertu res and the isthmus with age. With one exception, the cochlear aqueduct was always present and patent.