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January 16, 2004

First Successful Use of Penetrating Microelectrodes in Human Brainstem Restores Some Hearing to Deaf Patient

From: Business Wire (press release) - Jan 16, 2004


Success caps 15-year effort by scientists, engineers and physicians of the House Ear Institute in Los Angeles and the Huntington Medical Research Institutes in Pasadena

Physicians of the House Ear Clinic have successfully implanted the first two patients with a Penetrating Electrode Auditory Brainstem Implant (PABI), a revolutionary prosthetic device that is currently in clinical trials. The PABI is based on cochlear implant technology, but extends the utility to stimulating the hearing portions of the brain to restore some degree of hearing function to people deafened by bilateral tumors on their hearing and balance nerves (vestibular schwannomas). The PABI is a modified version of the existing Auditory Brainstem Implant (ABI) with the addition of an assembly of microelectrodes, designed to penetrate into the auditory portion of the brainstem (cochlear nucleus) and send sound signals to the brain.

"The PABI, like the ABI, offers patients suffering from a genetic condition called NF2 an alternative to profound bilateral deafness," says Derald E. Brackmann, M.D., House Ear Clinic. "Extensive research by our Institute scientists and their collaborators to create this new PABI provides even more hearing benefits and hope to our patients."

The ABI, which was developed at the House Ear Institute (HEI) over two decades of research, was approved by the FDA in 2000 and has been implanted in more than 300 people worldwide. The new electrode array for the PABI was developed in close collaboration between research scientists and engineers at the House Ear Institute and Huntington Medical Research Institutes (HMRI) in the U.S. and Cochlear Limited in Australia, with funding from the National Institutes of Health. For the past twelve years, these experts have developed and tested the PABI to ensure the safety of the device for clinical use. The penetrating electrodes, which are surgically implanted following removal of a tumor, were designed and manufactured to safely stimulate the neurons in the brainstem. Patients who receive implantation of the by physicians of the House Ear Clinic (HEC) will be evaluated in the Department of Auditory Implants and Perception at HEI, where the research staff has extensive experience working with profoundly deaf patients using cochlear implants and ABIs.

"We anticipate that our first PABI patients may gain improved hearing benefits from the microstimulation of the brainstem with the new penetrating electrode array as compared to those who receive stimulation via the surface-electrode of the existing ABI," says Bob Shannon, Ph.D., House Ear Institute. "We hope that speech comprehension will be closer to that experienced by multi-channel cochlear implant users."

Like the ABI, the PABI is designed for patients suffering from Neurofibromatosis Type II (NF2), a hereditary disease that can cause profound hearing loss through the growth of bilateral tumors on the vestibular nerves. Because of the location of these tumors, their removal typically necessitates severing the auditory nerve. A cochlear implant cannot be used because the auditory nerve is not able to carry signals from the cochlea to the cochlear nucleus in the brainstem. Instead, the ABI or PABI applies a processed electrical signal directly to the auditory portion of the brainstem. Recipients of the existing surface-electrode ABI do not generally receive the level of benefit afforded to cochlear implant recipients because the surface electrodes do not make selective contact with the different pitch regions of the cochlear nucleus. The new PABI is designed to provide pitch-selective stimulation by inserting penetrating microelectrodes directly into the different pitch regions of the auditory brainstem.

"The PABI is the first clinical application of microelectrode technology, " says Doug McCreery, Ph.D., HMRI. "The HMRI team is proud to have collaborated with HEI, HEC and Cochlear Limited on this important project by developing the new penetrating electrodes and array, insertion instrument and safety testing with support from the NIH."

This project has been funded in whole or in part with Federal funds from the National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), under Contract No. NO1-DC-1-2105. Total NIDCD/NIH funding since June 1992 is $4,851,293. Funding to Cochlear Limited from the FDA was $300,000.

About the House Ear Institute

The House Ear Institute (HEI) is a private, non-profit 501(c)(3) organization dedicated to advancing hearing science through research and education to improve quality of life. Established in 1946 by Howard P. House, M.D., as the Los Angeles Foundation of Otology, and later renamed for its founder, the House Ear Institute has been engaged in the scientific exploration of the auditory system from the ear canal to the cortex of the brain for more than 55 years. Our scientists continue to explore the developing ear and ear diseases at the cell and molecular level, as well as the complex ear-brain interaction. They are also working to improve hearing aids and auditory implants, clinical treatments and intervention methods. For information on the House Ear Institute, please call 213-483-4431 or visit the Website at

About the Huntington Medical Research Institutes

The Huntington Medical Research Institutes (HMRI) is an independent, nonprofit, public-benefit organization dedicated to improving health and prolonging life by enhancing knowledge of life processes and disease, and by developing technology to diagnose and treat diseases. It is widely known for its development of the hydrocephalus shunt to treat "water-on-the-brain," for pioneering studies on biomedical applications of laser energy, basic and applied cancer research, development of electronic neural rehabilitation technology, studies in vascular biology and for development of methods and applications of magnetic resonance, including imaging (MRI) and spectroscopy. New programs include molecular oncology, molecular neurology and brain mapping magneto encephalography, (MEG) liver studies and asthma and allergy. For more information on HMRI, please call 626-397-5804 or visit

About Cochlear Limited

Cochlear Ltd. is the world leader in cochlear implant technology. Established over 20 years ago, Cochlear has over 50,000 implant recipients in more than 78 countries around the world. The development of the Penetrating Auditory Brainstem Implant (PABI) is the latest innovation in a long list of industry firsts. Driven by a foundation in good science and a lifetime commitment to cochlear implant recipients and the professionals who serve them, Cochlear continues to redefine the hearing implant industry with innovative, new technologies. For more information on Cochlear Limited, please call 800-523-5798 or visit

Additional PABI press materials are available at

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House Ear Institute (HEI)
Christa Spieth Nuber, 213-273-8027

© Business Wire 2004