My cochlear implant surgery didn't work. What can I do?
Cochlear implant performance depends on the device, electrode position, programming, the hearing nerve, and how the brain processes sound. Testing helps identify which factors are limiting your hearing and whether treatment should involve programming, rehabilitation, medical care, or surgery.
An important first question is whether your hearing has declined from a previous level or has never improved as expected. A decline raises concern for a new device or medical problem. Limited benefit from the start may involve electrode position, programming, or how the hearing nerve and brain respond to stimulation.
Which hearing tests may be performed?
These tests measure different parts of hearing. Being able to detect a sound does not necessarily mean you can understand speech.
| Test | What it measures |
|---|---|
| Aided sound-field audiogram | The softest tones you can hear through your implant across different pitches. This helps show whether your programming provides access to soft sounds. |
| CNC word testing | Your ability to repeat individual words without sentence clues. Scores include whole words and individual speech sounds. |
| AzBio sentence testing | Your ability to understand sentences in quiet and background noise. |
| BKB-SIN testing | How much louder speech needs to be than background noise for you to understand it. |
| Unaided audiogram, when relevant | Any remaining natural hearing, especially if you use an implant with an acoustic hearing component. |
Results should be compared with your earlier scores under similar test conditions. Testing each implant separately can help identify a problem that is masked when both ears are used together. Your daily listening experience also matters, since test scores may not capture fatigue, distorted sound, or difficulty in groups.
Which tests check the device and its programming?
The external processor, microphones, cables, and coil are checked first. Substituting working equipment can help determine whether an external part is responsible.
Additional testing may include:
- Electrode impedance testing: Measures resistance to electrical current at each electrode contact. It can detect an open circuit, where the electrical path is broken, or a short circuit, where current takes an unintended path. High resistance can also reflect tissue changes around the electrodes rather than device failure.
- Manufacturer integrity testing: A more detailed check of the internal electronics and electrode system. This may require the manufacturer’s support. Repeated testing can help when symptoms are intermittent.
- Map assessment and loudness balancing: Checks the lowest stimulation levels you can hear and the upper levels that remain comfortable. It also checks whether loudness is balanced across electrodes.
- Electrically evoked stapedius reflex thresholds—eSRT: Measures a small middle-ear muscle’s response to implant stimulation. This can help guide upper stimulation levels, especially when judging loudness is difficult. A measurable response is not available in every patient.
A normal integrity test does not rule out every device problem. Persistent symptoms with normal testing may raise concern for “soft failure,” but other causes must be considered before recommending replacement.
Which tests assess the hearing nerve’s response?
These tests record electrical responses rather than requiring you to repeat words.
- Electrically evoked compound action potentials—ECAP: Measures how the hearing nerve responds to stimulation from the implant. Depending on the manufacturer, this may be called NRT, NRI, or ART. It can help with programming and show whether a measurable nerve response is present. It does not directly measure speech understanding.
- Spread-of-excitation testing—SOE: Uses recordings of the hearing nerve’s response to assess how widely electrical stimulation spreads. It is used mainly in research and specialized implant centers, rather than as a routine test for poor performance. In selected cases, it may help assess overlap between electrodes or detect an electrode tip that has folded over.
- Electrically evoked auditory brainstem response—eABR: Uses sensors on the scalp to record responses along the hearing pathway toward the brainstem. This is a specialized test for selected cases, such as uncertainty about the hearing nerve’s response.
These tests provide clues, but none can fully measure hearing nerve health or predict speech understanding on its own.
Which tests check electrode position?
The electrode array is the thin set of electrical contacts placed inside the cochlea. Its position can affect how well it stimulates the hearing nerve.
- Plain X-ray: Can show the array’s overall shape and identify a folded tip or a major change in position.
- High-resolution temporal bone CT or cone-beam CT: Provides a more detailed view of insertion depth, contacts outside the cochlea, and the array’s position within the cochlea’s internal chambers. Specialized image processing may help clarify these details.
- Transimpedance matrix testing—TIM: Measures how electrical voltage spreads between electrode contacts. In supported implant systems, an unusual pattern can help detect a folded tip or other placement concerns. Related electrical-field tests have different names across manufacturers.
Normal routine impedance results do not prove that the electrodes are correctly positioned. Electrical-field testing and imaging answer different questions and may be used together. CT is useful for position, but it usually cannot identify a failure inside the implant’s electronics.
Are there tests for inner-ear health or speech processing?
Selected centers may offer electrocochleography—ECochG, which records the inner ear’s response to sound. Some systems can record these responses through the implant. Research links these measurements with differences in speech understanding, but ECochG is not a routine or definitive test for every person with limited implant benefit. Its usefulness depends on the clinical question and available equipment.
When appropriate, testing may also include:
- Montreal Cognitive Assessment—MoCA: A screening test of attention, memory, and other thinking skills. A hearing-adapted version or suitable accommodations can reduce the effect of hearing difficulty on the results.
- Verbal fluency testing: Measures how easily someone retrieves words within a set time.
- Formal neuropsychological evaluation: A more detailed assessment when there are broader concerns about memory, attention, or language.
These assessments can help guide rehabilitation. They should not be used to assume that poor implant performance means cognitive decline. Research suggests that both inner-ear function and cognitive skills contribute to speech understanding, especially in noise.
Does everyone need all of these tests?
No. A typical evaluation starts with an examination, speech testing, an equipment check, and a programming review with electrode measurements. Imaging, manufacturer testing, and specialized nerve or cognitive tests are added when they can answer a specific question.
Treatment may involve replacing external equipment, changing the map, turning off selected electrodes, treating a medical condition, or targeted hearing rehabilitation. Surgery is considered when the findings support a correctable device or placement problem, or when substantial difficulties persist despite a thorough evaluation.
Contact your implant team promptly for a sudden hearing decline, repeated sound interruptions, new facial twitching, shocking sensations, pain, or dizziness. Redness, swelling, drainage, or skin breakdown at the implant site also needs prompt evaluation.
