Microneedle Intracochlear Delivery Round Window Perforation
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Solution Overview
Problem
Current methods for intracochlear drug delivery, such as implants, are often permanent and invasive, causing trauma to the round window membrane (RWM) and leading to hearing loss and perilymphatic leakage, necessitating a minimally traumatic and effective method for RWM perforation and drug administration.
Innovation Solution
A microneedle system with a sharpened distal tip and a shaft of 75-150 microns outer diameter and 15-50 microns inner lumen diameter, mounted on a blunt metallic syringe needle, is used to perforate the RWM, allowing for the injection of therapeutics into the inner ear with minimal trauma and controlled volume delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If direct intracochlear injection through the RWM is performed, then greater concentrations of therapeutic are achieved, but hearing loss and perilymphatic leakage occur
Solution Approach 1:
The patent changes the physical parameters of the injection needle by using an ultrafine microneedle with an outer diameter of 50-150 microns and an inner lumen diameter of 10-30 microns. This parameter change allows the needle to create a precise, controlled perforation in the RWM that enables therapeutic delivery while minimizing tissue damage and perilymphatic leakage, thereby resolving the contradiction between achieving high therapeutic concentration and preventing hearing loss.
Solution Approach 2:
The microneedle delivers therapeutic directly to a specific local area (the RWM) with precision control. The localized quality of the needle tip (sharpened for minimal trauma) and the controlled injection volume (1-10 microliters) ensure that the therapeutic concentration is maximized at the target site while the overall trauma to the RWM is minimized, preventing hearing loss.
2Reliability
If permanent implants are used for intracochlear access, then reliable long-term dosing is achieved, but significant lifestyle modification is required
Solution Approach 1:
The patent employs a disposable microneedle system that provides temporary, non-permanent access to the cochlea. The microneedle is designed to be single-use, eliminating the need for permanent implants and the associated lifestyle modifications. After the therapeutic is delivered, the microneedle is removed and the RWM heals naturally, providing a temporary but sufficient solution that does not require long-term commitment or lifestyle change.
Solution Approach 2:
The microneedle system transitions from a static, permanent implant to a dynamic, temporary access method. The needle can be inserted and removed as needed, allowing flexible dosing schedules without the constraints of permanent implantation. This dynamic approach maintains reliability for the duration of the therapeutic course while eliminating the need for permanent lifestyle modification.
3Ease of operation
If conventional RWM perforation methods are used, then intracochlear injection is achieved, but significant perilymphatic leakage occurs
Solution Approach 1:
The patent fundamentally changes the parameters of the perforation tool by using a microneedle with extremely fine dimensions (outer diameter 50-150 microns, inner lumen 10-30 microns). This parameter change creates a perforation that is just large enough to allow therapeutic delivery while being too small to cause significant perilymphatic leakage, thus resolving the contradiction between injection accessibility and perilymphatic loss.
Solution Approach 2:
The microneedle acts as an intermediary tool that mediates between the injection system and the RWM. Its ultrafine tip creates a controlled, minimal-trauma perforation that serves as a bridge for therapeutic delivery without creating a large opening that would cause perilymphatic leakage. The microneedle protects the RWM from excessive damage while still enabling effective injection.
Data Source
AI summary
A method for injecting a therapeutic into the inner ear of a subject comprising providing a microneedle having a sharpened distal tip and a shaft with a maximum outer diameter of about 75 microns to about 150 microns, the microneedle defining an inner lumen with a diameter about 15 microns to about 50 microns; the inner lumen having a curvature near the needle tip such that the lumen opened at the side of the needle proximal the needle tip; the microneedle mounted on a blunt metallic syringe needle; the blunt metallic syringe needle attached to a syringe secured to a micropump; advancing the microneedle into the middle ear space and the perforating the round window membrane (RWM) with the needle tip; extending the needle such that the inner lumen is disposed in the inner ear space; injecting a volume of therapeutic into the inner ear space; and retracting of the microneedle from the RWM.