Radiologic study of a disposable drug delivery intracochlear catheter

1) To assess the insertion characteristics of a disposable intracochlear catheter; and 2) to assess radiologically cochlear trauma induced by delivery catheter and electrode arrays.

A catheter was designed to enter the scala tympani up to 15 mm and to acutely deliver pharmacological agents during cochlear implantation.

A cadaveric study was conducted in accordance to national regulation. Thirteen fresh temporal bones were evaluated radiologically. The intracochlear catheter used in this experiment has the same outer dimensions and profile as a standard MED-EL cochlear implant electrode array. We performed sequentially the introduction of the catheter, the injection of an iodine solution into the scala tympani via the catheter, the removal of the catheter, and finally an electrode array insertion. Ten to 15 μl of an iodine solution was injected into the scala tympani at depth of 15 mm. Four CT scans were sequentially performed after each step.

The disposable intracochlear catheter could easily be inserted in all specimens. An insertion at depth of 15 mm was easily achieved every time. CT scans demonstrated that the iodine solution injected stayed in the scala tympani in all specimens. This was interpreted as indirect evidence of the integrity of the basilar membrane.

Drug delivery during cochlear implantation using a flexible disposable intracochlear catheter has been demonstrated to be feasible and without radiological evidence of basilar membrane trauma to a distance of up to 15 mm, as demonstrated in 13 temporal bones.