Cortical reorganization following auditory deprivation predicts cochlear implant performance in postlingually deaf adults

Abstract

Long-term hearing loss in postlingually deaf (PD) adults may lead to brain structural changes that affect the outcomes of cochlear implantation. We studied 94 PD patients who underwent cochlear implantation and 37 patients who were MRIscanned within 2 weeks after the onset of sudden hearing loss and expected with minimal brain structural changes in relation to deafness. Compared with those with sudden hearing loss, we found lower gray matter (GM) probabilities in bilateral thalami, superior, middle, inferior temporal cortices as well as the central cortical regions corresponding to the movement and sensation of the lips, tongue, and larynx in the PD group. Among these brain areas, the GM in the middle temporal cortex showed negative correlation with disease duration, whereas the other areas displayed positive correlations. Left superior, middle temporal cortical, and bilateral thalamic GMs were the most accurate predictors of post-cochlear implantation word recognition scores (mean absolute error [MAE] = 10.1, r = .82), which was superior to clinical variables used (MAE: 12.1, p < .05). Using the combined brain morphological and clinical features, we achieved the best prediction of the outcome (MAE: 8.51, r = .90). Our findings suggest that the cross-modal plasticity allowing the superior temporal cortex and thalamus to process other modal sensory inputs reverses the initially lower volume when deafness becomes persistent. The middle temporal cortex processing higher-level language comprehension shows persistent negative correlations with disease duration, suggesting this area's association with degraded speech comprehensions due to long-term deafness. Morphological features combined with clinical variables might play a key role in predicting outcomes of cochlear implantation.

The timecourse of multisensory speech processing in unilaterally stimulated cochlear implant users revealed by ERPs

“…Given that life expectancy and the exposure to noise are rising, hearing problems will become increasingly prevalent in the ageing population ( Sun et al, 2021 ). Therefore, treatment methods have to be optimised, as hearing loss is an important factor influencing the quality of live (confirmed here with the NCIQ).…”

Brain Morphological Modifications in Congenital and Acquired Auditory Deprivation: A Systematic Review and Coordinate-Based Meta-Analysis

“…The reported volumetric changes in the insula vary considerably and range from a GM increase in the posterior left insula ( Allen et al, 2008 ) to an overall bilateral GM decrease ( Olulade et al, 2014 ). A recent study reported a GM decrease in the right insula in postlingual deafness ( Sun et al, 2021 ), a finding which was confirmed in a meta-analysis and meta-regression study ( Manno et al, 2021 ). Conflicting results were also reported for the insular WM, going from a bilateral decrease in deaf compared to normal hearing signers ( Olulade et al, 2014 ) to a WM increase in the right insula in SL users (comparison between deaf and normal hearing signers, and normal hearing non-signers) ( Allen et al, 2008 ).…”

“…In children, the results were inconsistent, some reporting increases and others decreases in GM in STG. A recent study conducted in a large cohort of 94 postlingually deaf adults, not included in the ALE analysis because of lack of MNI coordinates, found a global GM decrease in the superior, middle and inferior temporal cortices ( Sun et al, 2021 ). This study further showed an interaction between GM changes and duration of deafness: the decrease in the middle temporal cortices was found exclusively in participants who had been deaf for more than 10 years, whereas the decrease in the superior temporal cortices was limited to participants who had been deaf for less than 10 years.…”

“…Although cortical plasticity following loss of vision has been described in detail [see Kupers and Ptito (2014) ; for a review], there is a relative sparsity in studies on brain plastic changes following auditory loss. There is some evidence that structural and functional brain changes can impact rehabilitation with a CI ( Lee et al, 2007 ; Lazard et al, 2013 ; Tan et al, 2015 ; Feng et al, 2018 ; Han et al, 2019 ; Wang et al, 2019 ; Sun et al, 2021 ). Furthering our understanding of brain plasticity and its structural substrate in deafness is therefore of utmost importance to improve therapeutic outcomes of CI therapy.…”

Altered Functional Network in Infants With Profound Bilateral Congenital Sensorineural Hearing Loss: A Graph Theory Analysis

“…However, the functional connectivity between the thalamus and middle temporal gyrus was previously found to be decreased in SNHL adults (Xu et al, 2019). The cortical thickness of the middle temporal gyrus was found to be increased in postlingually deaf adults (Pereira-Jorge et al, 2018) but decreased in prelingually profound SNHL children (Qu et al, 2020) and postlingually deaf adults (Sun et al, 2021). Thus, we speculated that the functional and structural changes in the middle temporal gyrus in SNHL patients will differ between children and adults, and between prelingually deaf patients and postlingually deaf patients.…”