ALZET pump implantation in mice for chronic drug delivery to the cochlea

Drugs, chemical compounds, and other elements are often delivered to the ears of experimental animals to manipulate cochlear function, study how the ear works, identify drugs that prevent hearing loss, and test for ototoxicity. Delivery procedures for acute studies have been described in the literature. However, detailed information on methods that allow weeks of continuous drug delivery to the mouse cochleae is sparse. This paper describes a method for chronic drug delivery to the mouse cochlea. We illustrate the steps for the surgical implantation of an ALZET infusion pump and the placement of its catheter. We propose a ventral approach to the cochlea, using a surgical laser to make the cochleostomy and the placement of the pumps' delivery ports into scala tympani with an orientation toward the cochlear apex. The catheter's orientation toward the cochlear base often affects the vestibular system and is not favored for placement.