The FDA has approved a new type of surgically implanted hearing device
intended to help adults with moderate to severe nerve hearing loss. The
device, the first of its kind, is an alternative to traditional hearing
Made by Symphonix Inc., of San Jose, Calif., the device is implanted
behind the ear in the temporal (skull) bone. It takes sound and converts
it to mechanical energy that is directly transferred to the middle ear.
This energy vibrates delicate structures in the middle ear in a manner
very similar to normal sound. By contrast, regular hearing aids that are
placed inside the ear simply magnify sound.
With the new Vibrant Soundbridge, a receiver is surgically implanted
behind the ear. A wire leads down to a small electromagnet attached to
one of the middle ear bones. The vibrations are then interpreted as
sound by the brain.
In clinical studies, the product was shown to be reasonably safe and
effective. While the new product was less visible than some standard
hearing aids and did not have associated problems such as ear wax and
moisture, implantation of the new device requires surgery and has the
risks associated with many surgical procedures.
FDA approval of the implant was based on a review of the clinical
study conducted by Symphonix at 10 medical centers in the United States,
on supporting data from European studies, and on the recommendation of
the Ear, Nose and Throat Panel of FDA's Medical Devices Advisory
Committee which met in July to evaluate the product.
In the U.S. study, 81 patients were first tested with hearing aids
in both ears and then with the implant in one ear. The patients were
followed for at least nine months.
Study results showed that participants could hear about as well with
the implant as with hearing aids.
Complications included worsened hearing (2%), permanently altered
taste (2%), long-term pain in the ear (5%), and a permanent feeling of
fullness in the ear (16%).
Symphonix is conducting an 18-month follow-up study of certain study
participants to evaluate the long-term safety and effectiveness of the
The firm has developed two patient information booklets: one for
people who may be considering having this device implanted, the other
with post-operative care instructions for patients who have had the
The Symphonix implant should not be confused with cochlear implants
that are intended as a surgical treatment for the profoundly deaf.
Cochlear implants are electronic systems that send sound-generated
impulses directly to the cochlea, thereby bypassing the middle ear.