June 15, 2007
Researchers at Georgetown University Medical Center and the National Institutes of Health (NIH) have, for the first time, used a "bionic" ear to restore hearing in a patient with von Hippel-Lindau disease. They say this advance offers new hope for individuals with the rare disorder, which can produce non-malignant tumors in ears, as well as in the eyes, brain, and kidneys.
The advance was possible, researchers say, because their years of research into the disease showed that these tumors do not affect the cochlear nerve necessary for receipt of sound in the brain. The device they used is known as a cochlear implant, which stimulates the cochlear nerve with electrical impulses. It is predominately used to treat the deaf.
"Based on our understanding of how these tumors affect the inner ear, we felt that a cochlear implant could work, and it did," says the study’s lead author, H. Jeffrey Kim, M.D., an assistant professor in the Department of Otolaryngology – Head and Neck Surgery, and a part-time investigator at the NIH, where the surgery was performed. Two years after the surgery, the implant has significantly improved the quality of life of the patient, he says.
Based on this successful surgery, which was published as a case report in the May issue of the journal Otology & Neurology, patients with von Hippel-Lindau disease with hearing loss may be now be candidates for a cochlear implant, Kim says. The disease, caused by inheritance of a mutated tumor suppressor gene, occurs in 1 out of 36,000 live births, and about 30 percent of these patients develop tumors in their ears – often in both. To date, the only option to help control these tumors is repeated surgery, which is often not successful, he said. Loss of hearing is sudden, and hearing aids don’t help, Kim said.
These tumors occur in the endolymphatic sac, part of the inner ear labyrinth of fluid passages. They are benign, but are invasive, and can cause hemorrhages that lead to tinnitus, vertigo, and hearing loss. Kim and his colleagues have been following a population of patients with the disorder and are national leaders in characterizing the disorder’s effect on the ears. They have published a series of findings in such journals as the New England Journal of Medicine (NEJM) and the Journal of the American Medical Association (JAMA).
Kim’s research also sheds light on other ear problems, including Ménière’s Disease, a disorder of the inner ear that can affect hearing and balance due to pressure in the same endolymphatic sacs. "This is a much more common condition, so we hope that what we learn from von Hippel-Lindau disease may help in the treatment of hearing problems that affect many of us," he says.