Through which of the following route can infection of CNS spread?

There are four routes for the spread of CNS infection into the inner ear: Hematogenous route ( through blood supply to the labrynth) Through direct extension along the meninges and auditory nerve Through fluid pathways from the CNS either, from CSF to perilymphatic compament along the cochlear duct or alternatively into the endolymphatic compament through the endolymphatic duct Through the oval or round window afte establishing a middle ear infection.