Cochlear Aqueduct in Infants

Abstract

In six infant ears the cochlear aqueduct had an average length of 3.5 mm while that of adults was earlier found to measure 6.2 mm. The width of the aqueduct was relatively large being at least 150 μm at the narrowest point, 0.5–1 mm from scala tympani. The canal lumen was filled with arachnoid meshwork allowing the passage of erythrocytes into the scala tympani. No barrier membrane appeared at the scala tympani opening and at the meningeal side the dural sheet maintained a tubular canal which opened into the subarachnoid space adjacent to the glossopharyngeal nerve near the jugular bulb. Corpora amylacea were not seen. The arachnoid meshwork thus provides a patient pathway for fluid transport between CSF and perilymph. The relatively large size of the short aqueduct explains why infectious meningeal processes in childhood may reach the inner ear while protection apparently occurs by soft tissue swelling at the meningeal side of the aqueduct.