Severance Hospital surpasses 3,000 hearing implant surgeries

Severance Hospital has reached a major milestone in hearing loss treatment, successfully performing over 3,000 hearing implant surgeries, solidifying its position as a national leader in auditory rehabilitation and precision medicine.

The human hearing process involves the outer ear, middle ear, and inner ear. Sound waves are collected by the outer ear, amplified by the ossicles in the middle ear, and transmitted to the cochlea in the inner ear.

Within the cochlea, vibrations of lymphatic fluid stimulate hair cells in the organ of Corti, which convert mechanical signals into electrical signals. These are relayed via the auditory nerve to the brain, where they are interpreted as sound.

Hearing loss occurs when any part of this auditory pathway is disrupted and is broadly categorized into conductive hearing loss and sensorineural hearing loss.

Conductive hearing loss, involving issues in the outer or middle ear, is typically treatable with hearing aids. Mild to moderate sensorineural hearing loss can also benefit from hearing amplification. However, in cases of severe to profound hearing loss due to damage to cochlear hair cells or the auditory nerve, even loud sounds become unintelligible.

Cochlear implants offer a solution by bypassing the damaged structures and directly converting sound into electrical signals. The external sound processor converts environmental sound into digital signals, which are transmitted to an internal implant. The implant delivers these signals as electrical stimuli to the cochlea, enabling the auditory nerve to send decipherable information to the brain.

In addition to cochlear implants, Severance Hospital also performs other forms of hearing implant surgery tailored to different types of hearing loss.

These include middle ear implants, which stimulate the ossicles directly for clearer, more natural sound in patients unable to wear hearing aids, bone conduction implants, which deliver sound vibrations through the skull for patients with outer or middle ear malformations, and auditory brainstem implants (ABI), used in cases where the auditory nerve is absent or severely damaged, requiring direct implantation into the brainstem.

Severance Hospital has played a pioneering role in this field since 1988, when the late Professor Kim Hee-nam of the Department of Otorhinolaryngology successfully performed Korea’s first cochlear implant surgery. At the time, the device cost nearly $20,000 and was funded through collective contributions from faculty members and support from former Yonsei University College of Medicine Dean Lee You-bok.

The hospital marked its 1,000th case in 2013 and its 2,000th in 2019. Now, it has surpassed 3,000 hearing implant procedures, which include 2,376 cochlear implants, 408 middle ear implants, 190 bone conduction implants, and 26 auditory brainstem implants.

Severance alone accounts for approximately 40 percent of all middle ear implant procedures in Korea, which total about 1,000 cases nationwide.

The hospital also holds a number of “firsts” in Korea.

In 2008, the late Professor Lee Won-sang and Professor Choi Jae-young performed the country’s first auditory brainstem implant, a complex procedure that involves brain surgery and is available only at a few specialized institutions.

In 2011, Professor Choi performed Korea’s first middle ear implant, expanding treatment options for patients who cannot benefit from conventional hearing aids. Since 2014, Professor Moon In-seok and colleagues have published more than 10 studies in top international journals to refine patient selection criteria for middle ear implants.

Severance’s greatest differentiator lies in its commitment to precision medicine. Over the past 15 years, Professor Jung Jin-sei has analyzed the genetic data of more than 3,500 patients with hearing loss, tailoring diagnosis, treatment, and prognosis based on individual genomic profiles. Combining implants with targeted drug therapies has shown promising results.

For instance, patients with OSBPL2 or NLRP3 mutations have experienced improved hearing and reduced tinnitus following treatment with rapamycin or anakinra. Professor Jung and Professor Choi have also co-developed and licensed new therapeutic agents targeting mutations in the pendrin and KCNQ4 genes.

Rehabilitation is essential after hearing implant surgery.

Despite surgical success, patients often require mapping to adjust the frequency and range of sounds they perceive. Severance Hospital’s multidisciplinary team -- including audiologists, speech-language therapists, social workers, and the Hanim Center for Precision Medicine -- ensures personalized and integrated care throughout the recovery process.

Since 2012, the hospital has also operated "KT Having Dream Center,” a long-standing corporate social responsibility initiative sponsored by KT, to support pediatric cochlear implant patients in their auditory and social rehabilitation.

The program offers not only language therapy but also art, music, and English classes to foster children’s growth as socially integrated individuals.

Severance has shared this model with other regions in Korea, including South Jeolla Province, Jeju Island, and North Gyeongsang Province, and has extended its outreach internationally.

In 2019, the hospital launched the second KT Having Dream Center in Cambodia, marking the first such auditory rehabilitation program for hearing-impaired children in the country.

“Over the past 40 years, Severance has led transformative innovations in hearing restoration,” Professor Choi said. “What sets us apart is our integrative approach, which combines genetic diagnostics, tumor-related therapies, pharmacological and surgical interventions, to provide optimal care for patients with hearing loss.”