Hearing preservation in cochlear implantation surgery

In order to preserve the residual hearing in patients with sensorineural
hearing loss (SNHL) receiving a cochlear implant (CI), the insertion trauma to
the delicate and microscopic structures of the cochlea needs to be minimized.
The surgical procedure starts with the conventional mastoidectomy-posterior
tympanotomy (MPT) approach to the middle ear, and is followed by accessing the
cochlea, with either a cochleostomy (CO) or via the round window (RW). Both
techniques have their benefits and disadvantages. Another aspect is the design
of the electrode array. There are fundamentally two different designs: a
*straight* lateral wall lying electrode array (LW), or a *pre-curved*
perimodiolar cochlear lying electrode array (PM). Interestingly, until now, the
best surgical approach and type of implant is unknown. Our hypothesis is that
the combination of a RW approach and a LW lying electrode array minimizes
insertion trauma, leading to better hearing outcome for SNHL patients.

Comparison of hearing preservation and outcome of two fundamentally different
cochlear implants designs (LW or PM) and the two most used surgical approaches
(RW or CO). Secondly, asses the structure preservation (i.e., scalar position)
of each combination of electrode design/surgical approach. Thirdly, find
objective electrophysiological measures for insertion trauma.

Randomized controlled single-blind trial consisting of four groups: I: RW and
LW, II: RW and PM, III: CO and LW and IV: CO and PM.

Randomisation to one of the four groups.

Cone-beam CT (CB-CT) imaging postoperatively leads to exposure of low-dose
radiation (effective dose: 0.18 mSv), and is therefore considered to be of
low-risk.