The most dramatic change in technology has been the shrinking of implantable stimulators. Compared with the original implants, the new stimulators are approximately 50% of their thickness or less, Dr. Buchman noted. This has enabled surgeons to create reliable implant fixation while avoiding the need for a bony seat or recess for the device in most instances. Now, the devices can slide under the temporal periosteum or muscle alone. “They don’t stick up as much [from the skull] and there are fewer skin reactions related to the site,” Dr. Buchman said.
Explore this issue:November 2017
All three stimulators, Dr. Lalwani said, look very similar and contain sophisticated electronics that are designed not to fail. “The expectation is that the CI will last a lifetime,” he added. Dr. Buchman agreed: “The new implants have become much more reliable, both the internal and external devices, which is really good news.”
In addition to the thickness of the implant, there have been advances in the design of the electrodes that run from the stimulator into the cochlea. “There is evidence that the outcome after cochlear implant is not as good when there is trauma to the cochlea compared to atraumatic procedures [Ear Hear. 2013;34:413-425]. The electrodes that attach to the cochlea implant have also gotten much smaller, thereby reducing the risk of damaging the fragile structures inside the cochlea,” Dr. Lalwani said.
Today’s external processors are like mini-laptop computers. There are a number of pre-processing strategies taken from hearing aid technology that improve performance. One example is the use of dual or directional microphones, Dr. Buchman said, “which has been very helpful in improving hearing in noise.” Fortunately, many of the older speech processors for implants can have their operating systems upgraded by the manufacturers, Dr. Buchman added.
In addition, manufacturers are working on improving battery life. Pre-curved electrodes that hug the cochlear modiolus have the potential to extend battery life between charges. “If the electrode is placed closer to the nerve endings, the amount of energy required to stimulate the nerve is less. The theoretical advantage is that with less energy required for nerve stimulation, more precise stimulation with less interaction in channels that are adjacent to each other is possible,” Dr. Lalwani said.
Wearing options have also improved patient satisfaction. “Cochlear implants used to be a technological wonder, but it has now become a consumer product in the sense that you have all these choices to make with respect to color, size, shape—all sorts of things,” Dr. Lalwani said. One company makes a waterproof speech processor (Advanced Bionics) that allows users to swim underwater, which is especially important to children, Dr. Lalwani noted. Other companies also have products that protect the external component from water damage.