Sound-induced drug distribution in the cochlea, how close are we? A PRISMA scoping review.

Objective: To evaluate the efficacy of sound stimulation for enhancing drug distribution in the cochlea's perilymph, crucial for treating one of the most inaccessible organs and a major disability factor worldwide.

Design: A systematic scoping review following PRISMA guidelines was conducted, analysing studies on cochlear fluid dynamics influenced by sound stimulation. Data were collected from PubMed and Google Scholar using both MeSH and non-MeSH terms, with exclusions for unrelated topics.

Study sample: Thirteen studies met the inclusion criteria, providing insights into the mechanics of cochlear perilymphatic flow and its potential enhancement through sound stimulation.

Results: The review highlights two primary mechanisms capable of inducing significant perilymphatic flow from the base towards the apex: complex audible sound stimulation creating a "streaming channel" and low-frequency stimulation at high intensity. Despite the theoretical potential, the clinical applicability of these techniques remains unproven, and the safety of low-frequency, high-intensity stimulation for the cochlea and vestibular system should be demonstrated.

Conclusions: Sound stimulation appears to be a viable method for inducing perilymphatic movements, potentially improving drug delivery to remote cochlear regions. Future research should focus on the clinical safety and efficacy of these stimulations to fully utilise this approach in therapeutic applications.