Visual cues support auditory recovery after cochlear implantation, with evidence showing cross-modal plasticity enhances speech perception and rehabilitation outcomes.
Traditionally, clinical guidance around cochlear implantation has been shaped by a key concern: that reliance on visual communication, particularly speechreading, might hinder auditory recovery after implantation. While many clinicians no longer hold this view, its legacy still influences how some patients and families think about visual support.
The logic was straightforward: deafness leads to ‘cross-modal plasticity’, a phenomenon where the auditory cortex begins responding to visual signals [1]. If this visual takeover becomes strong, might it compromise the brain’s ability to adapt to electrical stimulation from a cochlear implant (CI)?
This assumption influenced counselling, early intervention policy and rehabilitation practice. Some centres historically discouraged visual communication, notably sign language or structured speech-reading, believing it could make later auditory adaptation harder.
However, a surge of research over the last 10–15 years has fundamentally challenged this view. Rather than competing with auditory recovery, visual cues appear to support and enhance it. Cross-modal plasticity is now recognised not as a barrier but as a resource: a way the brain remains active and ready to integrate new auditory inputs [1]. As the field moves forward, the evidence increasingly suggests that clinicians should encourage, not discourage, the use of visual cues before and after cochlear implantation. Much of the early evidence, and most of the neuroimaging work discussed here, comes from studies in adults, though many of the underlying principles also apply to children.
Cross-modal plasticity: the brain’s adaptive response to sensory loss
When auditory input is lost, the auditory cortex does not fall silent. Instead, it begins to respond to other sensory modalities – most commonly vision [1]. This cross-modal plasticity reflects adaptive reorganisation within existing neural pathways. Rather than representing a pathological takeover, it demonstrates that the cortex remains functionally engaged.
Far from indicating deterioration, visual responsiveness in auditory cortex shows that multisensory networks remain active.
"Cross-modal plasticity is now recognised not as a barrier but as a resource: a way the brain remains active and ready to integrate new auditory inputs"
This is important because higher-level auditory processing is inherently multisensory. Speech perception relies on integrating visual signals (lip movements, facial expressions) with sound. The famous McGurk effect illustrates how deeply intertwined these modalities are. With this in mind, it becomes clear that strengthening visual pathways is not detrimental, it may provide scaffolding that supports the later restoration of hearing.
Predicting outcomes: visual activation as a positive prognostic sign
One of the strongest challenges to the ‘visual takeover is harmful’ hypothesis comes from CI-compatible neuroimaging techniques, such as functional near-infrared spectroscopy (fNIRS). Unlike functional MRI, fNIRS is unaffected by CIs and can easily be used to measure cortical activation in deaf adults.
In a longitudinal study involving adult CI candidates, activation of the superior temporal cortex to visual speech predicted significantly better speech perception outcomes six months after implantation [2]. These findings remained robust even after adjusting for duration of deafness and age at onset of hearing loss.
Rather than suggesting maladaptive changes, greater visual responsiveness following cochlear implantation appears to reflect a brain that remains flexible, engaged, and ready for auditory learning.
These results echo growing behavioural evidence that good speech readers often become good CI users [3], not because they rely more on vision but because the neural systems supporting speechreading overlap with those supporting higher-level speech processing generally.
Auditory and visual processing recover together
A key finding from longitudinal imaging is that auditory and visual responses often change in parallel after implantation. That is, as auditory activation increases, visual activation tends to increase as well [2]. This directly contradicts the idea of a forced competition between modalities.
Such evidence suggests that multisensory engagement is part of the natural trajectory of successful rehabilitation. The brain appears to integrate new auditory input rather than replace existing visual strategies.
Preclinical models show the power of multisensory training
Important support comes from bilateral cochlear implant animal models. Early-deafened animals typically show poor spatial hearing after implantation, even when given significant auditory experience. However, when auditory cues are paired with visual stimuli, simulating structured audiovisual training, their auditory cortex develops clearer spatial selectivity and behavioural sound localisation improves [4]. Remarkably, these improvements persist even after visual cues are removed. The visual input appears to help train the auditory system, not simply compensate for its weakness.
This has profound implications for clinical rehabilitation. If the auditory cortex can be ‘retuned’ with visual support, then structured audiovisual training could become an important part of CI habilitation, especially for long-term or early-onset deafness.
Implications for clinical practice
While the supporting evidence differs between adults and children, the overarching principle that visual communication supports rather than undermines auditory development appears consistent across age groups. Taken together, these findings argue strongly for a shift in guidance and patient counselling. Rather than presenting visual communication as a risk factor that must be minimised, clinicians should openly discuss how visual cues may support recovery [5].
- Reassuring patients and families
Families may worry that using sign language or relying on speechreading before implantation will reduce the benefit of the CI. Current evidence suggests the opposite: maintaining rich, meaningful communication, including visual modes, helps keep multisensory systems active and supports later auditory learning [5]. - Incorporating visual training into rehabilitation
Audiologists and speech therapists may wish to integrate structured audiovisual exercises into early rehabilitation. Visual cues can help patients establish phonemic categories, improve temporal alignment and increase confidence in noisy environments. - Encouraging continued visual support postoperatively
Rather than asking patients to avoid speechreading, clinicians can emphasise its value as a natural communication tool that supports rather than competes with auditory perception. - Personalising therapy based on cortical measures
Techniques like fNIRS could eventually help identify patients who may benefit most from multisensory-focused rehabilitation strategies [3].
Conclusion: visual cues should be embraced, not avoided
The field is moving toward a more nuanced, evidence-based understanding of cross-modal plasticity. Instead of seeing visual activation as the enemy of auditory recovery, we should view it as an adaptive mechanism that keeps the auditory cortex functional during deprivation and primes it for successful rehabilitation. More broadly, re-engaging multisensory cortical networks after implantation may have implications beyond hearing, potentially supporting attention, working memory and other cognitive processes that are closely linked to speech perception.
The weight of evidence now supports a shift in practice: encouraging, rather than discouraging, the use of visual cues, both before and after cochlear implantation.
As clinicians, our role is to promote the strategies that give patients the best chance of meaningful, sustainable hearing. Visual engagement is one of them.
References
1. Kral A, Sharma A. Crossmodal plasticity in hearing loss. Trends Neurosci 2023;46(5):377–93.
2. Anderson CA, Wiggins IM, Kitterick PT, Hartley DE. Adaptive benefit of cross-modal plasticity following cochlear implantation in deaf adults. Proc Natl Acad Sci U S A 2017;114(38):10256–61.
3. Moberly AC, Pisoni DB, Tamati TN. Audiovisual Processing Skills Before Cochlear Implantation Predict Postoperative Speech Recognition in Adults. Ear Hear 2024;45(3):617–25.
4. Isaiah A, Vongpaisal T, King A, Hartley DE. Multisensory training improves auditory spatial processing following bilateral cochlear implantation. J Neurosci 2014;34(33):11119–30.
5. Wallace MT. Cooperation between hearing and vision in people with cochlear implants. Proc Natl Acad Sci U S A 2017;114(38):10003–5.
Declaration of competing interests: DH is employed by Rinri Therapeutics and has shares in the company.
