As is usually the case, the argument has been reduced to semantics. For those of us who are not doctors, when we refer to the skull we usually are referring to the hard bone in our heads that encases and protects the brain. The mastoid bone which is a part of the lower skull is that bump you can actually feel right behind your ears. It is not a hard solid bone such as the skull encasing your brain but rather a honeycombed bone. It is through that bone, the mastoid, that a hole is drilled, better yet, here is a very good description of the cochlear implant surgery from the University of Miami's website:
Cochlear implant surgery lasts about two hours and is performed while the patient is under general anesthesia. Some conditions that may affect the cochlea, such as cochlear ossification (bony growth) or cochlear abnormalities may lengthen the time of surgery. Prior to surgery, a small portion of hair is shaved around the ear to be implanted. A small seat is created in the mastoid bone to hold the receiver/stimulator and protect it. The surgeon drills through the mastoid bone to the inner ear. The electrode array is then inserted into the cochlea. The receiver/stimulator is secured to the skull, and the incision is closed with stitches. Typically, patients return home the day of surgery.
As usual, the anti-ci crowd uses the semantical argument as a scare tactic. From Harlan Lane incorrectly calling cochlear implant surgery "brain surgery" on '60 Minutes' to posters on this forum repeatedly using terms such as "drilling a hole in your skull" or "carving up your skull", they are attempting to create the misimpression that the hole is through the hard bone, which we commonly call the skull, into a person's brain when that is completely erroneous and misleading.
It is through the mastoid folks, plain and simple. Although for most of you anti-ciers you really have nothing to fear for as you repeatedly demonstrate through your posts, even if a surgeon was to drill through your skulls, there is nothing in there for him to damage!
Rick