Minimally-invasive access into the cochlea for electrode insertion and fluid delivery

Abstract

A threaded grommet, having an axial passageway therethrough, and made from a biocompatible material, such as titanium, is screwed into a cochleostomy made in the bony tissue adjacent the round window in order to provide a minimally-invasive access port into the cochlea. The threads included on the outside of the grommet engage the bony tissue and form a tight seal that holds the grommet securely in position. Such tight seal prevents cochlear fluids from escaping from inside of the cochlea. The axial passageway through the center of the grommet provides an opening, i.e., mechanical access, into the base end (the end of the cochlea nearest the round window) of the cochlea. Drugs, steroids, tissue-growth-inhibiting fluids, and the like, may be controllably delivered through the access hole into the cochlea, which access hole may be plugged when not needed. Additionally, an electrode array, e.g., a relatively short electrode array may, be inserted into the cochlea through the access hole. A preferred electrode array has from four to eight electrode contacts spaced apart along a flexible carrier. The flexible carrier is about 6-8 mm in length. The electrode contacts may be connected, in conventional manner, to suitable implantable cochlear stimulator (ICS), or equivalent pulse generator. Neither the grommet nor the short electrode array interfere with the normal hearing processes within the cochlea. Hence, both electrical stimulation and normal hearing processes may occur simultaneously within the cochlea.