Following cortical mastoidectomy and posterior tympanotomy, carrying out a cochleostomy or preparing the round window, and inserting the electrode array of the cochlear implant. The receiver-stimulator package is placed into the well created in the cortex of the temporal bone.

Cochlear implantation surgery.

The cortical mastoidectomy has been completed, and the posterior tympanotomy carried out. During the operation, exenteration of the mastoid cavity is restricted to a smaller size as a smaller cavity enables better electrode array fixation.

DR: Digastric ridge

EAC: External auditory canal

MCF: Middle cranial fossa (dural plate)

SS: Sigmoid sinus (dural plate)

The view of the middle ear through the posterior tympanotomy opening. The critical structures of the tympanic cavity, i. e., the stapes, pyramidal process, and round window, can be seen.

PB: Posterior buttress

PP: Pyramidal process

RW: Round window

SH: Stapes head

SPI: Short process of incus

TSM: Tendon of stapedius muscle

The microsurgical instrument, which has been inserted through the posterior tympanotomy opening, is pointing to the round window. The round window is the site of insertion for the electrode array in the “round window technique” and the main landmark for the drilling site in the “cochleostomy technique”.