University Professor Dr. med. Claudia Rudack is one of Germany’s leading experts in otorhinolaryngology (ear, nose, and throat medicine). Since 2012, she has led the Department of Otorhinolaryngology at University Hospital Münster with outstanding professional expertise and genuine dedication — one of the most tradition-rich institutions of its kind nationwide.
Prof. Dr. Rudack stands for highly specialized diagnostics and state-of-the-art therapies for disorders in the delicate head and neck region. Her surgical expertise spans advanced middle ear surgery and cochlear implantation, complex skull-base procedures, and plastic-reconstructive facial surgery. Under her leadership, the department has evolved into a nationally recognized center for ENT medicine — with clear focal areas in head and neck oncology, ear diseases, nasal and paranasal sinus disorders, as well as allergic conditions and sleep-related breathing disorders.
Whether pediatric or adult, outpatient or inpatient: With more than 8,000 patient contacts and around 4,000 surgeries annually, the ENT Department under Prof. Dr. Rudack offers comprehensive, modern, and patient-centered care. Candidates for cochlear implants receive individualized support from the preoperative evaluation through surgery and on to follow-up care. A special emphasis is placed on subsequent semi-inpatient hearing and speech rehabilitation for children — including those with multiple disabilities — as well as for adults. Close collaboration exists with schools for hearing and communication, rehabilitation clinics, local speech-language pathologists, and self-help groups.
The editorial team at the Leading Medicine Guide spoke with Prof. Dr. Rudack to learn more about hearing implants — particularly cochlear implants (CIs).
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Hearing loss is a widespread phenomenon that affects people of all ages and can significantly impact daily life and social participation. This reduction in hearing can result from a range of factors such as aging, noise exposure, or genetic predisposition. Although there are varying degrees of hearing loss, an effective solution is available to many: the hearing aid. Hearing aids are an essential support that enables those affected to manage everyday life and remain active participants in social interaction. They not only improve communication, but also enhance general well-being and quality of life. However, if the sensory cells in the cochlea are severely or irreparably damaged so that the ear can no longer adequately transmit sound, then a cochlear implant makes sense. 
Human auricle. _Peter Niemayer, CC BY-SA 3.0
A modern behind-the-ear hearing aid with a miniature cell battery. _Jonn Leffmann, CC BY 3.0
Estimates suggest there are about 15 million people with hearing impairment in Germany. Of particular relevance for cochlear implantation are the approximately 6 million who are severely to profoundly hard of hearing.
„In the 50- to 60-year-old age group, about one in five has some form of hearing loss. Nevertheless, only about 3.1 million people in Germany wear a hearing aid, indicating that hearing-aid provision is underrepresented. This undersupply may be due to the high costs of hearing aids and to hesitation about visiting an ENT specialist or a hearing-care professional. In a health study — the Gutenberg Study from Mainz — it was found that of nearly 5,000 patients examined, about 7.7 percent wore bilateral hearing aids. However, 47 percent of patients met the criteria for a pure-tone audiometric hearing loss, which means not everyone in need is actually being fitted. Typically, older individuals report that they need to turn up the television volume or that conversations become difficult to understand. A hearing test can then clarify how well someone hears and whether a hearing aid — or even a cochlear implant — is necessary. Today’s hearing aids are small and discreet, and they are particularly suitable for treating mild to moderate hearing loss. A hearing aid simply increases the sound pressure in the middle ear. Normally, sound waves travel through the external auditory canal to the eardrum, which sets the ossicular chain in motion. The stapes then transmits the sound waves to the inner ear, the cochlea. The cochlea is filled with fluid and equipped with sensory cells that convert mechanical energy into electrical signals and relay them to the auditory cortex in the brain. This type of amplification is sufficient as long as the sensory hair cells in the cochlea are intact“, explains Prof. Dr. Rudack at the beginning of our conversation.
Outer ear, middle ear, and inner ear. _Lars Chittka_ Axel Brockmann, CC BY 2.5
There are different types of hearing-implant systems that are used depending on the type and degree of hearing disorder as well as anatomical conditions.
- Cochlear implants (CI):
These are used in cases of severe to profound sensorineural hearing loss or deafness when conventional hearing aids are no longer sufficient. A CI bypasses the damaged hair cells in the cochlea and directly stimulates the auditory nerve.
- Bone-conduction implants (e.g., BAHA, Bonebridge):
These systems transmit sound through bone directly to the inner ear. They are used for conductive or mixed hearing loss, for example when the ear canal is absent or closed, in chronic middle-ear infections, or for single-sided deafness.
- Middle-ear implants (e.g., Vibrant Soundbridge):
Suitable for people with mild to severe conductive, sensorineural, or mixed hearing loss. The implant transmits sound signals mechanically to the ossicles or directly to the inner ear.
Size comparison of the human stapes with a 10-euro coin. _Welleschik, CC BY-SA 3.0
- Auditory brainstem implants (ABI):
These are used when the auditory nerve itself is damaged or absent — for example in certain tumors or malformations. The implant stimulates the auditory pathway directly in the brainstem.
A hearing implant is considered when conventional hearing aids no longer provide sufficient speech understanding — that is, when no satisfactory improvement can be achieved despite optimally fitted hearing aids. Timing depends on the degree, type, and progression of hearing loss.
„A cochlear implant is essentially an electronic inner-ear prosthesis that is inserted directly into the cochlea and powered externally. The implant generates electrical stimuli that stimulate the auditory nerve, which then transmits signals to the auditory cortex in the brain. The implant consists of an external and an internal component. The external component — the sound processor — looks like a modern hearing aid and is worn behind the ear. It picks up sound, converts it into electrical signals, and transmits them to a coil placed on the skin. Internally lies the actual implant, which processes the signals and forwards them to the electrode array in the cochlea. This electrode, whose length varies depending on the model, covers a defined frequency spectrum corresponding to the cochlea“, explains Prof. Dr. Rudack, adding:
„The indication spectrum has broadened significantly in recent years, so that people with single-sided deafness and even young children — who can be implanted from about nine months of age — now benefit. Previously, the minimum age was four years, but evidence that early auditory stimulation markedly promotes language development has fundamentally changed practice. There are now hybrid systems in which a hearing aid continues to amplify higher frequencies while the implant covers the lower frequency ranges. The individualized spectrum gives the medical team and patients ample room to ensure optimal care. Advances in technology have considerably expanded the possibilities of cochlear implantation in recent years, enabling more and more people to compensate for hearing loss with modern means and their own initiative“.
External unit of a cochlear system. _I, Ydomusch, CC BY-SA 3.0
A patient’s age plays a significant role in selecting a specific hearing implant, as it affects expectations, anatomical and physiological prerequisites, and the likelihood of success.
„There is no fixed upper age limit. The oldest patient I have implanted was 86, but age per se is not decisive. Far more important is assessing rehabilitative capacity and the ability to handle the device. This assessment is now interdisciplinary, considering not only the degree of hearing loss but also motor and cognitive prerequisites. While device handling is doable, it is not trivial — especially with varying ambient noise. In everyday life, it can be challenging to distinguish among different acoustic environments. In a quiet room, conversation partners are typically easy to understand, but in noisy venues like concert halls or restaurants, fine-tuned settings are needed to facilitate hearing. Listening to music with a cochlear implant often remains difficult. Today, however, there are increasingly refined programming options — so-called strategies — that adjust different frequency bands. These are guided by cochlear anatomy: low frequencies are represented toward the apex of the cochlea (higher turns), high frequencies more basally (lower turns). The implant is inserted up to the apex, and the electrode contacts can be addressed individually. Depending on the manufacturer, there are varying numbers of contacts — for example 16 or 21 — which can be programmed physiologically to optimally represent each frequency range. A CI technician or CI audiologist performs the fine-tuning and adjusts the frequency bands based on physiological principles. This so-called ‘anatomy-based fitting’ is now standard and helps patients learn to hear more easily after optimization and quickly achieve intelligibility in as many situations as possible“, notes Prof. Dr. Rudack.
Cochlear implant on a man. _Hear hear!, CC BY-SA 4.0
In children, the time window for language development is crucial. The earlier a hearing disorder is detected and treated with an appropriate implant, the greater the chances of age-appropriate speech and communication development. Especially in congenital or early-acquired deafness, early CI provision (often within the first year of life) is essential to sufficiently stimulate the neural structures for hearing. During this phase, the brain is particularly receptive to acoustic stimuli — a “critical time window” that does not remain open indefinitely.
The surgical implantation of a hearing device — especially a cochlear implant (CI) — is a well-established routine procedure, nonetheless performed with the necessary care and preparation.
„Head surgery, particularly in the ear region, is undoubtedly demanding. It is considered a relatively complex procedure with certain risks; perioperative risk is assessed individually in advance. Many candidates are older adults, which makes anesthesiology evaluation especially important. Before surgery, the patient’s health is thoroughly reviewed — blood pressure, cardiac function, and other relevant factors — to keep anesthesia risk as low as possible and ensure a safe process. The operation itself is essentially a medium-complexity ear surgery. The approach is postauricular. An incision of about six centimeters is made to expose the skull bone (calvarium). The mastoid is then drilled to gain access to the cochlea. All steps are performed under microscopic visualization using a drill. The goal is to access the cochlea at the round window — a membrane separating the middle ear from the cochlea. This membrane is incised, typically only about 1.5 millimeters, to allow entry. The electrode is carefully advanced through the slit into the cochlea — sometimes cleaning is necessary or anatomical peculiarities must be considered, such as in children with a shortened or dysplastic cochlea“, says Prof. Dr. Rudack, emphasizing:
„The key step is to insert the electrode slowly and in a controlled manner; studies show that a cautious insertion over about seven minutes preserves cochlear function. There are now special robots that perform this insertion mechanically, very slowly and precisely, which according to current studies leads to better hearing outcomes. The operation usually takes about an hour. Intraoperative measurements follow: An audiologist tests electrical thresholds, assesses auditory-nerve responses, and ensures the implant is functioning properly. These measurements are crucial to configure the device and begin the initial programming so that the patient can hear optimally afterward“._ b=Hammer_ c=Amboss_ d=Steigbügel_ e=Mittelohr._Zoph, CC BY-SA 3.0.png "a=eardrum (red), b=malleus, c=incus, d=stapes, e=middle ear. _Zoph, CC BY-SA 3.0")
a=eardrum (red), b=malleus, c=incus, d=stapes, e=middle ear. _Zoph, CC BY-SA 3.0
In the long term, placing a cochlear implant (CI) generally has very positive effects on speech understanding and quality of life for both children and adults — provided medical prerequisites are met and follow-up care is consistent.
After surgery, patients begin an extensive rehabilitation phase lasting about a year, supported by a specialized interdisciplinary team that oversees follow-up care. „At the first programming, about 14 days after surgery, the device is adjusted to ensure basic functionality and to enable the patient to hear. A technician activates the device, explains the basic functions, reviews the remote control, and shows how to turn the device on and off. The aim is to acclimate the patient to the environment and gather first impressions. During this phase, the patient must practice at home — for example, turning the device on and off — to enable an initial hearing experience. The approach is similar for adults and children, though timing and goals differ“, explains Prof. Dr. Rudack, highlighting specific considerations for affected children:
„In children, indications for cochlear implantation are fundamentally different. Some children become deaf in the first or second year of life due to specific conditions; others are born deaf. In early childhood deafness, the challenge is to teach the child both hearing and language. This is complex: in children who have previously heard, the brain is already imprinted, and hearing must simply be reactivated. In deaf children, however, auditory and language development must first be built, requiring longer and more intensive support. Early implantation is critical to success. Children who receive a cochlear implant early can now attend mainstream school as early as first grade. Early provision makes it possible to optimally foster language development and facilitate integration into regular education“, says Prof. Dr. Rudack.
Woman with hand to ear _AI generated
Following this initial step, fine-tuning takes place as part of so-called basic care sessions. Here, the device is readjusted weekly to optimize individual hearing comfort. At the same time, a speech-language pathologist provides training focused on sound perception, single-word recognition, and specific phoneme practice. Special tools and hearing-training programs are used regularly during the first four weeks, usually weekly. Subsequently, training intervals become longer, followed by additional sessions that typically last about 11 to 15 minutes.
„These training sessions take place either in a day clinic, via the health insurers, or in inpatient CI rehabilitation clinics. The most common in Germany include those in Hanover, which follow their own inpatient concept. If the patient is well programmed and hearing development remains stable, they return for checkups twice a year. We assess how well the implant is functioning and make adjustments — varying greatly depending on individual progress. Why some patients perform better than others is not yet fully understood. A great deal of data is therefore being collected, for example in the national cochlear-implant registry established in 2021. These data help improve prognostics — predicting how well a patient will hear with the implant, whether music will be well perceived, or how successful language development will be“, reports Prof. Dr. Rudack.
A cochlear implant (CI) is a highly effective yet complex hearing solution. Compared with other implants such as middle-ear devices or bone-anchored systems (BAHA), it entails specific risks and limitations — medical, technical, and practical.
„Head surgery is considered complex and carries certain risks, so the perioperative process is carefully planned and monitored. The surgical technique itself is essentially a medium-complexity ear procedure: an approximately six-centimeter incision is made behind the ear to expose the skull bone. The mastoid is drilled to gain access to the cochlea. Everything is performed under microscopic view with a drill. The goal is to create an opening at the round window membrane, which is incised, and the electrode is carefully advanced through the membrane into the cochlea. At times, anatomical particularities must be considered, for example in children with a shortened or dysplastic cochlea. Modern developments have led to very gentle electrode insertion. Studies show that slow insertion — typically at least six minutes — is less traumatic to the cochlea. Robotic-assisted techniques now exist in which a robotic arm inserts the electrode with millimetric precision and slow speed, which current studies suggest leads to better outcomes. The surgery usually takes about an hour. Afterward, intraoperative measurements are performed: an audiologist assesses electrical thresholds, checks nerve responses, and verifies that the implant is properly activated. These data form the basis for the first device programming so the patient can hear as well as possible later“, emphasizes Prof. Dr. Rudack.
Part of the overall treatment complexity is assessing specific risks. The vestibular system is located in the ear and is closely connected to the auditory organ. As a rule, procedures here do not cause problems.
Prof. Dr. Rudack concedes: „In some older patients, postoperative dizziness can occur but usually resolves within a few weeks. The vestibular organ itself is generally not damaged unless anatomical peculiarities are present. With intraoperative nerve-monitoring systems, the risk of facial-nerve injury is also minimized. Fortunately, intraoperative nerve injuries are extremely rare. Because the inner ear connects to the brain’s cerebrospinal fluid space, there is an additional infection risk. For this reason, all patients must be vaccinated against pneumococci to prevent possible meningitis. In pathologies such as vestibular schwannoma, the situation is more complex. This benign tumor affects the nerve that governs balance and hearing. It may occur in the internal auditory canal, the cerebellopontine angle, or even in the brain. Precise evaluation is necessary in such cases. Tumor growth can impair the auditory nerve or cause tinnitus and balance disorders. Treatment ranges from watch-and-wait to radiosurgery (e.g., Gamma Knife) to surgical removal. The trend is increasingly toward minimally invasive radiation therapy — especially for small tumors — to minimize surgical risks. For larger tumors, or when the nerve is already damaged, careful consideration is required to determine whether a cochlear implant makes sense. If the auditory nerve is completely interrupted by surgery or no longer conducts, an implant is not useful. Alternative options must then be considered. In short, this complex matter is highly situation-dependent and requires careful, interdisciplinary coordination“.
Vestibular schwannoma. _Partynia, CC BY-SA 4.0
It was once assumed that all patients — even those deaf for 30 or 40 years — could be implanted successfully. However, this has proven not to be so straightforward. Over many years without auditory input, the auditory cortex receives no signals.
„For example, the visual cortex becomes highly activated in long-term deaf patients because they rely on lip-reading and visual cues to understand communication. This is called cortical reorganization: the cortex shifts its activity, with active areas migrating primarily to the visual cortex. Recovery of auditory function after cochlear implantation therefore depends greatly on the duration of hearing loss or deafness. The longer the period without acoustic input, the less readily the original auditory areas can be reactivated. The brain, in a sense, ‘forgets’ how to hear — a form of unlearning. Once the implant is activated, it must be reprogrammed regularly to achieve the best results. The implant itself remains in place and does not require frequent replacement; it is designed for long-term use and generally intended to last a lifetime. The speech processor — the external component — can be upgraded periodically, often every five years, to leverage the latest technology and processing strategies. Updated chips reflect the current state of the art, improving speech processing and optimizing outcomes“, states Prof. Dr. Rudack.
The Department of Otorhinolaryngology at University Hospital Münster regularly hosts so-called CI Cafés where interested patients and users come together. They are introduced to handling cochlear implants, associated features, and smartphone interfaces — whether iPhone or Android. Companies present new developments that participants can try out. This not only builds confidence in using the technology but also reduces fear of it.
Person with smartphone _AI generated
„Each year, we perform about 120 cochlear implant surgeries in Münster. Looking ahead, we particularly hope for more precise prognostic factors that will allow us to reliably predict whether a patient will hear well with an implant. In pediatrics, the situation is evolving: Early approaches to gene therapy are underway in the United States. Many children born deaf have genetic defects — for example affecting the sodium-potassium balance of their inner-ear hair cells. Initial trials show that supplying the missing genes can foster the development of normal hearing — a very exciting development with the potential to fundamentally change care. We are also increasing our focus on health-services research to better understand prognostic factors and further improve CI programming. We aim to support patients beyond standard care through specialized studies — for example, on music perception. We continue our investigations into the link between hearing loss and dementia, as it is well known that hearing impairment is a risk factor for dementia. We plan to measure brain waves and cortical programming in patients with hearing loss — including CI users — to learn more about brain activity in relation to implant use. How the brain is ‘reprogrammed’ after cochlear implantation remains under-researched, and we intend to move this work forward. As for challenges, we must acknowledge that working with the technology can require more explanation for older patients. To reduce anxiety, we are employing innovative approaches such as remote fitting: our hearing-care professionals in regions with fewer services — for example, in Münsterland — can configure the device via video. Settings can be adjusted through video conferences, which greatly eases the burden on patients who would otherwise face long trips to Münster“, explains Prof. Dr. Rudack at the close of our conversation.
Our sincere thanks to Professor Dr. Rudack for this detailed insight into hearing-aid and implant technology!
