Marilyn Davidson reclaimed partial hearing when she became the first recipient of an auditory brainstem implant (ABI) in 1979. She lost her hearing due to the removal of large tumors (schwannomas) growing on her vestibular nerves. The first tumor appeared when she was in her thirties and was diagnosed by Dr. William F. House at the House Clinic. He explained that left untreated, the tumor could put pressure on her hearing and facial nerves, as well as the blood vessels supplying vital brain centers controlling respiration, blood pressure and heart function.

A few weeks later, neurosurgeon William Hitselberger, M.D., performed the surgery to remove the tumor. During the operation, he had to sever MariIyn's right hearing nerve, sacrificing the hearing in that ear. Marilyn adjusted to her unilateral hearing loss and was symptom free for 12 years. In her forties, she noticed that she was missing parts of telephone conversations and realized her symptoms had returned. She went back to Dr. House. Marilyn learned that she had neurofibromatosis type II (NF2) and that two more schwannomas were found on her left vestibular nerve. Surgery to remove them would most likely destroy her residual hearing, leaving her deaf.

Drs. House and Hitselberger were developing an experimental device through the late 1970s for patients who had lost their hearing due to surgical removal of bilateral schwannomas. This was the forerunner of the ABI. Unlike the cochlear implant, also pioneered by Dr. House, this device stimulated the cochlear nucleus in the brainstem rather than the auditory nerve leading from the inner ear to the brain. Until then, no one had ever regained any hearing after having their auditory nerves severed.

They asked Marilyn if she was willing to try this experimental brainstem implant as a possible means for restoring some of her hearing. They told her that this procedure had never been done before and they weren't sure what she would hear, if anything. Marilyn agreed to the surgery, and it was successful. When the device was activated, she became the first person ever to regain partial hearing with an implant that bypassed the auditory nerve. After a few weeks of testing, she learned to distinguish between different environmental sounds. The doctors were pleased with Marilyn's preliminary results, but when she began experiencing muscle twitches during testing, they decided to unhook the device.

Despite possible risks, Marilyn wanted to continue testing. She wanted the doctors to resume their research and insisted that they reactivate her device. She wouldn't be discouraged and they complied. The ABI has greatly enhanced Marilyn's quality of life, and enriched the lives of many other ABI users. "As the first ABI patient, I feel that I was in the right place at the right time to receive this new hearing technology," Marilyn said. "I had complete confidence in my doctors. I just knew they could help me. It has been a long, hard road, yet what an extraordinary experience!"