Most potential route for spread of infection from CNS to inner ear

Cochlear aqueduct is most potential route for spread of infection from CNS to inner earQ Cochlear aqueduct & vestibular aqueduct are 2 bony channels (canals) that connect inner ear (cochlea & vestibule respectively) to intracranial sub arachnoid space. Vestibular aqueduct contains endolymphatic duct filled with endolymph, which does not communicate freely with CSF as it ends in a cul de sac and forms a closed space. Whereas perilymph filled cochlear aqueduct is in direct continuation with the CSF which makes it a most potential route of infection. Hyle's fissure is present in early embryonic life that normally obliterates by 24 weeks of gestation. When persistent it provides a connection from middle ear to subarachnoid space.