The investigational device is designed to improve speech recognition for patients suffering from a hereditary disease called Neurofibromatosis Type II (NF2) that can cause profound hearing loss through the growth of bilateral tumors on the vestibular nerves.

The PABI is a modified version of the existing Auditory Brainstem Implant (ABI), which received approval from the Food and Drug Administration in 2000, using electrodes designed to activate hearing neurons with more precision in order to improve speech recognition.

The ABI and PABI differ from cochlear implant technology in that they stimulate the brain directly from the brainstem rather than stimulating the cochlea.

The new PABI device was developed by scientists and engineers at the House Ear Institute and Huntington Medical Research Institutes (HMRI) in the US, and Cochlear Limited in Australia.

PABI Graphic

* PABI Artwork (above) Courtesy of Cochlear Corporation/ Cochlear Limited

Press Release

FIRST SUCCESSFUL USE OF PENETRATING MICROELECTRODES IN HUMAN BRAINSTEM RESTORES SOME HEARING TO DEAF PATIENT

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

LOS ANGELES – January 15, 2004 – 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 PABI 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 www.hei.org.

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 www.hmri.org.

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 www.cochlear.com.

Media Q&A

How is the PABI different from its predecessor, the ABI (Auditory Brainstem Implant)?

It uses electrodes designed to activate hearing neurons with more precision.

What are the expected auditory benefits of the PABI over the ABI?

It is hypothesized that users of the PABI may have improved speech recognition.

How are the PABI and ABI different from the cochlear implant (CI)?

The cochlear implant stimulates the cochlea (inner ear) while the ABI/PABI stimulates the brain directly from the brainstem.

Are the PABI/ABI and the cochlear implant based on
similar basic technology, and if so, which components are shared?

The external sound processor and transmitter, and the internal receiver and sound processing method are the same for the cochlear implant and the PABI/ABI systems.

Do you expect all PABI patients to receive the same benefits?

As with other prosthetic hearing devices, we would expect a large range of performance benefits between PABI patients, which is somewhat unpredictable.

Who invented the ABI technology and who developed the new PABI?

The House Ear Institute developed the first ABI technology. Later generations of ABI electrodes were developed cooperatively between HEI and Cochlear Corporation. Huntington Memorial Research Institutes (HMRI) developed the penetrating electrode array in cooperation with HEI and Cochlear Corporation.

What health considerations/issues would make someone a candidate for the PABI/ABI versus the cochlear implant (CI)?

Neurofibromatosis Type II (NF2), a hereditary disease that can cause profound hearing loss through the growth of bilateral tumors on the vestibular nerves, necessitates surgery to remove the tumors. In many cases, an ABI is
implanted during a surgery that removes the tumors to provide the patient with the means to receive some sound. (There are rare cases of bilateral absence of the cochlear nerve or bilateral damage to the cochlear nerve from accidents, where an ABI might be indicated.)

Can individuals who have the earlier version of the ABI upgrade their implant to the PABI?

Individuals who have the earlier ABI cannot upgrade their implant without further surgery and acceptance of the clinical trials status of the PABI. Removing and replacing electrodes is not recommended, however, a patient might consider implanting the other side with the newer PABI in a clinical trial.

What are the health risks, if any, involved in the surgery/implantation
of the PABI/ABI?

As with any prosthetic device, the patient must understand that the
device may not work for them, that there may be non-auditory sensations associated with the implant, and that there may be unknown effects from long-term use.

What kind of recovery period is required after the PABI implantation procedure, and is there any kind of speech therapy or rehabilitation provided afterward?

There is usually a one- week post-surgery stay in the hospital, followed by a 6-8 week recovery period at home, and then rehabilitation sessions at the House Ear Institute as part of ongoing follow-up.

Can you provide an example or demonstration of what a PABI candidate might expect to hear with this device?

Understandably, everyone would like to know what quality of sound a PABI candidate might hear. This is a very difficult thing to demonstrate, since only the PABI user will actually hear it and the quality of sound may vary among PABI users. Users of the existing ABI often describe sound as having a muffled quality or like a radio station tuned off-frequency. It may be that PABI users would hear a wider range of sound pitches and receive a less muffled quality of sound.

Can you please provide the names of the surgeons who performed this procedure, and the engineers and research scientists who developed the technology and device?

The surgeons were William Hitselberger, M.D., neurosurgeon, and Derald E. Brackmann, M.D., neurotologist. Steve Otto, CCC-A, is the research audiologist working with ABI and PABI patients. Robert V. Shannon, Ph.D. and
his research team at HEI developed the programming methodology for the PABI. Doug McCreery, Ph.D., HMRI, developed the penetrating electrode array for the device. The PABI device is manufactured by Cochlear Limited. The surgery took place at St. Vincent Medical Center in Los Angeles.

Fact Sheet

DESCRIPTION OF PABI:

The Penetrating Electrode Auditory Brainstem Implant (PABI) is a prosthetic device intended to restore some degree of hearing function to persons deafened by bilateral vestibular schwannomas (tumors on both balance nerves). The PABI is based on cochlear implant (CI) technology. It 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 to produce localized stimulation of the cochlear nucleus and send sound signals to the brain. Since its initial development at the House Ear Institute in 1979, the Auditory Brainstem Implant (ABI) has been implanted in more than 350 people worldwide. It received FDA-approval as a medical device in 2000, and is the only device that can restore limited hearing to people who have no remaining auditory nerves.

POTENTIAL BENEFITS OF PABI:

Most ABI recipients benefit from the device through increased sound awareness, which aids in lipreading. Because few ABI recipients are able to understand speech without lipreading, the level of performance achieved with the ABI is poorer than that obtained by people with a cochlear implant (CI). Cochlear implant research shows that speech understanding requires distinct stimulation of different pitch regions. The hypothesis is that the surface electrodes of the ABI can provide only limited pitch activation, whereas CI electrodes each elicit clearly distinct pitches. The reason for this may be that the surface electrodes of the ABI are not very closely connected with the pitch-specific organization of the auditory nervous system. It is hypothesised that the newer PABI, and the pitch-selective microstimulation provided by its penetrating electrode array, may provide speech comprehension closer to that experienced by multi-channel cochlear implant users. The PABI device can also function like the existing ABI because it also has a surface electrode array.

CANDIDACY FOR PABI:

Like the ABI, the PABI is designed primarily 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.

(There are rare cases of bilateral absence of the cochlear nerve or bilateral damage to the cochlear nerve from accidents, where an ABI might be indicated.)

RESEARCH AND DEVELOPMENT:

The PABI project is a collaboration between the House Ear Institute (HEI), Huntington Medical Research Institutes (HMRI) and Cochlear Corporation to develop a central auditory prosthesis based on intranuclear microstimulation. Penetrating microelectrodes for stimulation of the human cochlear nucleus have been under development for more than 12 years. The personnel of the Neural Engineering Program at HMRI have extensive experience in the development of stimulating electrodes, and in the development of protocols for safe electrical stimulation of nervous tissue. The tool for implanting the array into the brainstem also was developed at HMRI. The physical dimensions of the PABI electrode array are based on data from anatomical studies of the human auditory brainstem conducted at HEI by Dr. Jean Moore. Patients who receive the PABI at House Ear Clinic will be evaluated in the Department of Auditory Brainstem Implants and Perception at HEI, where the staff has extensive experience in the evaluation of profoundly deaf patients with ABIs and cochlear implants.

PABI Image 1

PABI Image 2

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