THE COCHLEAR AQUEDUCT IN PEDIATRIC TEMPORAL BONES

The cochlear aqueduct is a bony channel which contains the fibrous per iotic duct and connects the perilymphatic space of the basal turn of t he cochlea with the subarachnoid space of the posterior cranial cavity . Previous histological studies suggested that patency depended on age , whereas a more recent study showed no statistical correlation betwee n age and patency. To clarify patency in pediatric cochlear aqueducts, we selected 21 temporal bones from 12 infants and children, varying i n age from birth to 9 years, in which the cochlear aqueduct was fully visible on one histological section. Photographs were taken for docume ntation and the length and width of the orifice of the external apertu re of the aqueduct at the scala tympani were measured and followed to the internal aperture at the subarachnoid space. The lumen of the duct was examined for mononucleated cells, blood cells and fibrous tissue. Measurements revealed that the mean length of the cochlear aqueduct w as 4.6 mm (range, 2.4-10.7 mm), mean width of the external aperture wa s 484 mu m (range, 225-869 mu m), and mean width of the internal apert ure was 1293 mu m (range, 699-2344 mu m). The mean diameter of the nar rowest part (isthmus) was 151 mu m (range, 75-244 mu m). In all tempor al bones the cochlear aqueduct was patent, with one exception. This: l atter temporal bone was from a 2-month-old girl with multiple intralab yrinthine anomalies, with the missing cochlear aqueduct believed to be due to an aplasia. Our results support prior measurements of the coch lear aqueduct and demonstrate a short and patent cochlear aqueduct in newborns. With growth. a significant increasing length of the duct was found.