Blockage of the Cochlear Aqueduct

Abstract

An experiment was performed on guinea pigs to determine whether blockage of their cochlear aqueducts would cause any morphological changes in their inner ears and, in particular, whether it would cause endolymphatic hydrops. In 17 animals in which the cochlear aqueducts were successfully blocked without injury to other structures, there were no histological changes as determined by light microscopy after postoperative survival times of 1 to 7 months. Even by electron microscopy, fine structural alterations were not found. In 5 animals, with postoperative survival times of 2 to 5 months, in which both the cochlear aqueducts and vestibular aqueducts were blocked, there was endolymphatic hydrops and degeneration of sensory and neural structures in the same anatomical pattern and magnitude as that observed in previous experiments in which only the vestibular aqueducts were blocked. It is concluded therefore that the function of the cochlear aqueduct, in providing a wide communication between the cerebrospinal fluid and perilymph in most lower mammals and some humans, can be sacrificed with no ill effect on the normal inner ear. Other possible sources for perilymph are from the cerebrospinal fluid of the subarachnoid space of the internal auditory canal, and as a filtrate from the blood vessels of the inner ear.