At MED-EL, we see hearing preservation as the combination of technology, training and techniques to ensure that the delicate neural structures in the cochlea are left undamaged.
Hearing preservation is essential for all cochlear implant recipients for two main reasons. Firstly, helping to ensure that the neural structures in the cochlea are left undamaged is critical in enabling recipients to benefit from future therapies and technologies. It is likely that any future interventions, be they device, biological, or pharmaceutical in nature, will be more successful in a cochlea where the neural structures have been preserved.
Secondly, many individuals with severe to profound hearing loss may still be able to hear some low frequency sounds. This condition is referred to as residual hearing. It is vitally important to preserve this residual hearing during cochlear implant surgery as it enables the individual to use the natural hearing they have left. In combination with a cochlear implant, being able to use this natural hearing provides the user with the best possible listening experience.
Therefore, for all cochlear implant recipients, hearing preservation during a cochlear implant procedure is essential for their hearing both now and in the future.
Delicate neural structures of the cochlea
The cochlea is situated in the inner ear and is approximately 7mm in diameter or the size of a pea. In the cochlea are three fluid-filled canals (Figure 1) called the scala tympani, scala media and scala vestibuli. These canals are responsible for transmitting sound vibrations to the neural structures. It is in one of these canals that an electrode array of a cochlear implant is inserted.
Figure 1: Cross section of the cochlea showing the three fluid-filled canals
However, it has been established that the scala tympani is the ideal location for an electrode array 1. Due to their design, MED-EL electrodes are perfectly suited for insertion into the scala tympani.
Once in the scala tympani, it is also important that the electrode array does not perforate the wall of a neighbouring canal thereby destroying membranes and neural structures.
MED-EL electrodes have been specifically engineered to protect the neural structures of the cochlea. Due to their ultra-soft and flexible design the electrodes allow for gentle insertion causing minimal friction and optimal placement in the scala tympani.
MED-EL has 20 years of experience in the field of hearing preservation which has enabled us to engineer the softest and most flexible electrode arrays available. Because of this design, our electrodes help to reduce damage that could be caused by cochlear implant surgery.
The secret behind our soft and flexible electrode arrays lies within the custom made wires that transport the electrical signals inside cochlea. MED-EL has developed a wave-shaped wire design that enables the electrode to flex and bend making it perfectly suitable for insertion into the cochlea. Other manufacturers use straight wires in their electrode arrays. Using a straight wire adds unnecessary stiffness and rigidity to the electrode array.
An important aspect of hearing preservation is the special surgical techniques used. For that reason MED-EL offers many workshops to educate and teach professionals on the principles of hearing preservation and how to achieve the best possible results.