Isobel's Cochlear Implant

The Cochlea

 

INTERNAL PARTS 



This is the Maestro PULSARCI100 cochlear implant by MED-EL. This is the device that Isobel will be fitted with on Tuesday. Being a huge fan of labelling in my classroom, I feel reassured seeing that this has a clear label about the positioning requirements.

It is light weight, made from ceramic and has been specifically designed for children and infants. Again, being an art teacher, the ceramic nature of it plays to my sensibilities. I can't explain why, but it makes me feel more comfortable that it isn't titanium. This will be surgically placed under the skin just behind her ear.





This is a a close up of the electrode array that will be inserted into Isobel's cochlea. It's actual width is just 2.4mm and 31mm long. The cochlea, approximately 7mm in diameter, the size of a pea is one of only two organs that are full size when you are born. In the cochlea are three fluid-filled canals called the scala tympani, scala media and scala vestibuli. These canals are responsible for transmitting sound vibrations to the brain. It is in one of these canals that the electrode array of the cochlear implant will be inserted.



The cochlea converts sounds from mechanical vibrations into signals that are passed on to the brain via the auditory nerve. This process is performed by specialised hair cells inside the cochlea. These hair cells are arranged according to pitches or tones. This arrangement is referred to as tonotopicity. In normal hearing, low-frequency pitches cause nerve fibres to fire in the apex, or middle of the cochlea. High pitches cause nerve fibres in the base of the cochlea to fire. Isobel has difficulty with the low-frequency sounds, so she will need the electrode array to be fully inserted.

 

EXTERNAL PARTS

This is the audio processor that she will wear over her ear. It consists of a control unit, a battery pack, and a coil that transmits information through the skin to the receiver in the implant.

She will even have her own remote control!

HOW IT ALL WORKS