Surgeons from Massachusetts Eye and Ear Infirmary, Boston, and Massachusetts General Hospital will perform the first auditory brainstem implant (ABI) surgery in New England on May 20, according to Massachusetts Eye and Ear Infirmary, a teaching hospital of Harvard Medical School.
The ABI, which can restore the sense of hearing to certain patients, has been implanted in about 500 people worldwide, according to the hospital. Since its initial development in 1979 at the House Ear Institute in Los Angeles, and with its approval by the FDA in 2000, the ABI is used primarily to restore some degree of hearing loss due to neurofibromatosis type 2 (NF2), hospital officials say.
NF2 is a hereditary disease that causes the growth of multiple brain tumors, including bilateral tumors on both balance nerves, and because the auditory nerve is located near the balance nerve, the auditory nerve is damaged from tumor growth or surgical removal, according to the hospital. Once this happens, the auditory nerve is unable to transmit signals to the brain, causing deafness. Virtually all NF2 patients develop severe to profound hearing loss in both ears, according to the hospital.

Unlike a cochlear implant, the ABI bypasses the inner ear and auditory nerve and is surgically implanted on the cochlear nucleus, a bundle of nerves located on the brainstem, according to the hospital. The ABI electrically activates nerves in the brainstem and restores a sense of hearing to patients with NF2, hospital officials say. The current device is the only hearing option for deaf NF2 patients and allows them to hear sounds in their environment, such as horns and doorbells, as well as enhancing communication when combined with lip-reading, according to the hospital.  The ABI provides an option for those with hearing loss for whom other surgical methods to restore hearing loss are not possible, hospital officials say.

Encouraging new work from abroad has also shown the recent success of ABI to restore meaningful hearing in pediatric and adult non-NF2 patients who are deaf and cannot receive a cochlear implant, such as those born without an auditory nerve or others who have severely scarred inner ears, according to the hospital. Several FDA approved studies in the United States are now under way.
The ABI program at Massachusetts Eye and Ear Infirmary and Massachusetts General Hospital is comprised of a multidisciplinary team including audiologists, hearing scientists, neurotologists, and neurosurgeons, and provides clinical care to patients as well as performing research and development to discover ways to advance the technology and improve ABI performance, according to the hospital.

Objectives include working to develop a measurement system that would be used during surgical implantation to allow for more accurate location of the cochlear nucleus, as well as where to place the device on the cochlear nucleus to achieve the best results, according to the hospital.

This ABI surgery is scheduled to be performed at Massachusetts General Hospital by a team of specialists, and follow-up care will be provided at Massachusetts Eye and Ear, according to the hospital.

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[Source: Massachusetts Eye and Ear Infirmary]