By virtue of their design and the mechanics and dynamics of electrode insertion, all lateral wall electrodes will impact the lateral wall of scala tympani
. As the electrode is inserted, it will initially impact the lateral wall at approximately 180[degrees], after which the insertion force profile increases significantly as a function of the insertion depth, as does the frictional force, as the contact area between the spiral ligament and the silicone carrier of the electrode increases .
They aspirated a total of 10 [micro]l perilymph from the scala tympani
The scala tympani
was in depth; as such, we drilled deeply to explore it.
At surgery, patient was found to have significant ossification of the scala tympani
on both ears.
The fluid level of the perilymph in the scala tympani
was carefully lowered using cotton wicks so that only a very small amount of fluid (~30 [micro]m thick based on visual comparison with the known diameter of the probe tip) was left to moisten the exposed BM.
The position of the cochlear-implant electrode in the scala tympani
is important in the audiological results for cochlear implants .
A small hole was then made in the lateral wall at the basal turn of the cochlea, corresponding to the location of the scala tympani
. To avoid additional cochlear trauma, 5 [micro]L perilymph was removed slowly.
We conducted an animal experiment to investigate the effects of mechanical trauma to the round window with the placement of a model electrode inserted into the scala tympani
on the cochlear reserve, and to determine the efficacy of topical steroids in preventing hearing loss in such a situation.
The cochleostomy must be made inferior and slightly anterior to the round window rather than anterior to ensure scala tympani
insertion and to decrease the likelihood of insertion induced intracochlear damage, particularly the basal membrane and organ of corti during electrode insertion.
The cochleostomy was drilled in the promontory, anteroinferiorly to the membrane of round window to enter the scala tympani
where the electrode was inserted.
When surgery was attempted, cochleostomy revealed complete obliteration of the scala tympani
. Efforts to insert the electrode through the scala vestibuli were also unsuccessful.
The cochlea is basically compound from three fluid spaces (scala vestibuli, scala media and scala tympani
) which are divided by two membranes (basilar and Reissner's membranes).