Surgeons at University Hospitals Case Medical Center have completed the first auditory brainstem implant (ABI) operation in Northeast Ohio on a woman who has lost most of her hearing due to benign tumors on her auditory nerves.
The procedure was performed on March 11 by ear, nose and throat surgeons Cliff Megerian, MD, and Maroun Semaan, MD, and neurosurgeon Nicholas Bambakidis, MD. It will be about six to eight weeks before it is known if the implant provides benefit to the patient and to what extent.
The patient has a relatively rare genetic condition known as Neurofibromatosis Type 2 (NF2). The incidence is estimated to be one in 40,000.
Patients with NF2 develop usually benign tumors on the auditory nerves of both ears. These tumors gradually compress and destroy the auditory nerves and result in bilateral hearing loss and deafness. The patient noted gradual difficulty in hearing since 2002.
She had surgery and later radiation for her tumors, and was then treated with a cancer medication and a cochlear implant, but her hearing continued to decline. She has lost all hearing in her left ear and has partial hearing in her right ear.
"She is now struggling a great deal to maintain the pace she was used to in her daily life," said Dr. Megerian, who is Chairman and Professor in the Department of Otolaryngology Head and Neck Surgery at UH Case Medical Center and Case Western Reserve University School of Medicine. "An ABI is the only current available means to provide auditory rehabilitation to these patients."
An ABI is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf. It uses a similar technology as the cochlear implant, but instead of electrical stimulation being used to stimulate the cochlea, it is used to stimulate the brain stem of the recipient.
The ABI device includes a tiny radio receiver implanted underneath the skin and twenty- one 1-millimeter platinum electrodes implanted in the part of the hearing mechanism known as the cochlear nucleus.
Sounds, amplified and clarified by a special coil and miniature computer that slips onto the ear like a conventional hearing aid, are collected by the receiver, converted to electrical pulses and transmitted to the electrodes. From there the signals travel through the skin by radio frequency and connect to the brain stem at the same place the auditory nerve would normally connect.
There is great variability in terms of what and how much they can hear.
"While the effectiveness of ABI is limited, for someone who has lost most of her hearing, even having a partial return of sound is extremely helpful," said Dr. Semaan, Associate Director, Otology, Neurotology, and Balance Disorders at UH and Assistant Professor at Case Western Reserve University School of Medicine.
"The role of the Audiology and Intraoperative Neurosurgical Monitoring team is to confirm the presence of an auditory response once the ABI is placed. However, only when the ABI is fully activated 6 to 8 weeks after surgery will we be able to appreciate precisely how the patient is able to hear with the implant. An intensive auditory rehabilitation process will then begin to help the patient learn how to make use of the new sound," said Gail Murray, Ph.D., Director of Audiology and Cochlear Implants at UH and Associate Professor at Case Western Reserve School of Medicine.
Dr. Bambakidis, Director, Cerebrovascular and Skull Base Surgery at UH and Associate Professor at the CWRU School of Medicine, said, "This type of amazing technology is available only at institutions that have the expertise present to work together in a team approach for the treatment of complex skull-base pathology. To work properly, the ABI must be positioned perfectly on the surface of the brain stem, and requires the close collaboration of the ENT, Audiology and Neurosurgery teams. In our case we are fortunate in that we have had years of experience working together. Many institutions market themselves as having this sort of expertise available, but the Neurological Institute at UH truly can back up those claims with results from procedures such as this one."
While the ABI procedure was first done in California in the 1970s, this is only the first one in Northeast Ohio. The bulk of these surgeries performed nationally have been at the House Ear Clinic, located in Los Angeles, and which consulted on this case.
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Source: University Hospitals Case Medical Center