The electrode part of the cochlear implant is located in the 'scala tympani' chamber of the cochlea. A short period after implantation, a dense fibrous tissue sheath usually forms around this electrode.

The fibrous tissue sheath increases electrode impedance, meaning that the size of the electrical stimulus needed to excite the spiral ganglion nerve cells to induce a hearing sensation, needs to be increased. This can lead to voltage compliance problems and ultimately some electrodes on the cochlear implant electrode array may fail.

Electrical stimulation has been shown to lower electrode impedance, perhaps due to a reorganization of the fibrous tissue sheath over the electrode array. Standard clinical practice involves ‘switching on” recipients 2 to 4 weeks after implantation. One study within this project is looking at what happens when you provide electrical stimulation immediately after implantation. This study will look at the changes in electrode impedance and compare them to the fibrous tissue sheath that forms over the array.  If successful, further research will be undertaken to ensure there are no unwanted side effects with the early onset of stimulation.