TABLE 2.
Summary of diffusion tensor imaging studies of white matter structures in people with hearing loss
| Studies | Group | Age | Communication | Scanner strength |
Structure | Tissue | Measure | Analysis | Main result | Other results |
|---|---|---|---|---|---|---|---|---|---|---|
| Chang et al. (2004) | 10 D vs. 10 | 33.7 | NR but mild-to-severe HL | 3 T | SON, IC, TB, LL. AR | FA | Single brain analysis | Voxel-Wise | Abnormal | See also S. H. Lee, 2004 |
| Nath et al. (2007) | 14 D vs. 8 | 30 | NR | 1.5 T | LL | FA | Whole brain | ROI | Less | |
| IC | FA | Whole brain | ROI | Less | ||||||
| PCT | FA | Whole brain | ROI | Less | ||||||
| Y. Lin et al. (2008) | 37 D vs. 10 | 32.4 ± 11.9 | NR | 3 T | LL | FA and RD | Whole brain | DTIStudio | Less FA and more RD | |
| IC | FA and RD | Whole brain | DTIStudio | Less FA and more RD | ||||||
| Xia and Qi (2008) | 20 DS vs. 20 | 9–12 | CSL | 1.5 T | Right HG | ADC | Whole brain | ROI manual | Different | |
| 20 DS vs. 20 | 19–22 | CSL | 1.5 T | Bilateral HG | ADC | Whole brain | ROI manual | Different | ||
| S. Wang et al. (2009) | 6 CD vs. 6 | 20.8 | CSL (3 after HA usage at 4 years) | 3 T | Right STG | FA | Whole brain | Voxel-based analysis | Less | Asymmetry preserved |
| D. J. Kim et al. (2009) | 13 D vs. 29 | 29.3 ± 6.8 | No HA | 3 T | Superior temporal | FA | Whole brain | TBSS | Less | |
| Right internal capsule | FA | Whole brain | TBSS | Less | ||||||
| SLF | FA | Whole brain | TBSS | Less | ||||||
| Left inferior FOF | FA | Whole brain | TBSS | Less | ||||||
| Right forceps major | FA | Whole brain | TBSS | More | ||||||
| Left forceps major | FA | Whole brain | TBSS | More | ||||||
| Left STG | Volume | Whole brain | TBSS | Less WM | ||||||
| Right STG | Volume | Whole brain | TBSS | Less WM | ||||||
| Left parietal | Volume | Whole brain | TBSS | Less | ||||||
| Superior frontal | Volume | Whole brain | TBSS | Less | ||||||
| Medial frontal | Volume | Whole brain | TBSS | Less | ||||||
| Z.-H. Liu et al. (2010) | 15 D vs. 28 | 16 | CSL for more than 6 years and HA usage since 2 years old | 1.5 T | Left STG | FA | Whole brain | TBSS | Less | |
| Right STG | FA | Whole brain | TBSS | Less | ||||||
| Left IFG | FA | Whole brain | TBSS | Less | ||||||
| Right IFG | FA | Whole brain | TBSS | Less | ||||||
| Left post-medial MTG | FA | Whole brain | TBSS | Less | Reduction less in L than R | |||||
| Right post-medial MTG | FA | Whole brain | TBSS | Less | ||||||
| Right Int Cap | FA | Whole brain | TBSS | Less | ||||||
| Left Int Cap | FA | Whole brain | TBSS | Less | ||||||
| Right Ext Cap | FA | Whole brain | TBSS | Less | ||||||
| Left Ext Cap | FA | Whole brain | TBSS | Less | ||||||
| Left OR | FA | Whole brain | TBSS | Less | Reduction less in L than R | |||||
| Right OR | FA | Whole brain | TBSS | Less | ||||||
| Y. Li et al. (2012) | 60 CD vs. 36 AD vs. 38 | 21.1 ± 2.26 (CD), 21.5 ± 1.54 (AD) | CSL only | 3 T | Right STG | FA | Whole brain | TBSS | Less | Correlated with onset age |
| Left STG | FA | Whole brain | TBSS | Less | ||||||
| SCC | FA | Whole brain | TBSS | Less | ||||||
| Chang, Lee, Paik, Lee, and Lee (2012) | 18 D | 5.9 | NR | 3 T | Broca's | FA | Whole brain | Voxel-wise | Higher | Correlated with auditory scores after CI |
| Genu of CC | FA | Whole brain | Voxel-wise | Higher | Correlated with auditory scores after CI | |||||
| AR | FA | Whole brain | Voxel-wise | Higher | Correlated with auditory scores after CI | |||||
| MGN | FA | Whole brain | Voxel-wise | Correlated with auditory scores after CI | ||||||
| Miao et al. (2013) | 16 D vs. 16 | 14.56 ± 2.1 | CSL after late HA usage | 3 T | Left STG | FA and RD | Whole brain | TBSS | FA lower and RD higher | |
| Right STG | FA and RD | Whole brain | TBSS | FA lower and RD higher | RD correlated with CSL usage | |||||
| HG | FA and RD | Whole brain | TBSS | FA lower and RD higher | ||||||
| PP | FA and RD | Whole brain | TBSS | FA lower and RD higher | ||||||
| SCC | FA and RD | Whole brain | TBSS | FA lower and RD higher | ||||||
| Lyness, Alvarez, Sereno, and MacSweeney (2014) | 13 DS vs. 13 | 39.08 ± 11.08 | BSL after 10 years (11 used spoken language) | 1.5 T | Frontal and occipital | MD and RD | Thalamic Parcellation | FreeSurfer and FSL | Increased MD and RD | |
| Frontal | FA | Thalamo-cortical | FreeSurfer and FSL | Reduced FA | ||||||
| Motor | FA, MD and RD | Thalamo-cortical | FreeSurfer and FSL | Increased MD and RD | Reduced FA | |||||
| Somatosensory | FA and RD | Thalamo-cortical | FreeSurfer and FSL | Increased RD | Reduced FA | |||||
| Parietal | FA | Thalamo-cortical | FreeSurfer and FSL | Reduced FA | ||||||
| Occipital | FA | Thalamo-cortical | FreeSurfer and FSL | Reduced FA | ||||||
| C. X. Wu et al. (2014) | 92 (three groups) | 4.9 | 31 had CI | 1.5 T | STG | FA | Whole brain | DTIStudio | Less | |
| AR | FA | Whole brain | DTIStudio | Less | Correlated with CAP score in the 31 with CI | |||||
| Karns, Stevens, Dow, Schorr, and Neville (2017) | 23 DS vs. 26 | 28 ± 1.4 | ASL | 3 T | Bilateral HG, anterior STG, posterior STG | FA and volume | Whole brain | FSL | Less | More RD in bilateral HG; right posterior STG had larger differences between groups |
| Posterior CC | FA | Whole brain | FSL | Less | More RD | |||||
| J. Kim, Choi, Eo, and Park (2017) | 18 (10 postlingual) vs. 29 | KSL and HA | 3 T | Right Int Cap, right thalamus, SCC, right STG and left STG, right temporal lobe WM | Diffusion anisotropy | Whole brain | TBSS | Less | Prelingual less in R STG, bilateral WM, genu and anterior CC | |
| Maffei (2017) | 10 DS vs. 10 | 34 ± 6 | LIS | 4 T | Acoustic radiation | FA, RD and MD | Whole brain | FSL | Less, more | Atlas-based analysis, subset of Benetti et al. (2018) |
| Benetti et al. (2018) | 14 DS vs. 15 HS vs. 15 | 34 ± 6 | LIS | 4 T | Occipito-temporal, fusiform-temporal | FA and RD | Connectivity | FSL | Less FA and more RD | |
| Zou et al. (2018) | 80 vs. 78 | 41.7 | CSL for 10+ years | 3 T | Bilateral STG | GM and WM | Diffusion kurtosis | VBM (SPM) | Decreased | “Hypomyelination” of WM |
| Qi et al. (2019) | 35 vs. 23 | 39 ± 1.8 | NR | 3 T | Multiple WM structures | GM | FA | TBSS | Decreased | RD increased |
| M. Jiang et al. (2019) | 23 vs. 18 | 7.21 ± 2.67 | No HA usage | 3 T | Left ATR, right CST, CC | AD | Whole brain | TBSS | Increased | RD increased in several WM tracts |
| H. Wang et al. (2019) | 52 vs. 19 | 0.9–6 | Prior to CI | 3 T | Bilateral IC | FA | ROI | FSL, PickAtlas, SPM | Lower | Correlated with postop CAP scores |
| S. Wang et al. (2019) | 46 vs. 33 | 17.59 mo | Prior to CI | 3 T | Bilateral SLF, IFOF, ILF; right CST, PTR; left UF | FA | Whole brain | TBSS | Lower | Increased resting state functional connectivity between bilateral auditory cortices and right insula and STG |
| Cheng, Roth, Halgren, and Mayberry (2019) | 12 vs. 12 | 33.33 | ASL | 1.5 T | IFOF, AF, ILF, UF | FA | ROI | DTIStdio | No difference | |
| Dhir et al. (2020) | 5 DO vs. 10 | 31 ± 11 | LSL and HA | 1.5 T | AR | FA | Whole brain | MRICloud and DTIStudio | Less |
Note: Structures observed to be affected by hearing loss are shown in Figures 3 and 4. Gender information can be obtained from original papers and is not recorded here due to lack of correlation. Age is given as mean ± SD or mean.
Abbreviations: AD, acquired deaf; ADC, apparent diffusivity coefficient; AR/OR, acoustic/optic radiation; AF, arcuate fasciculus; ASL, American sign language; ATR, anterior thalamic radiation; BSL, British sign language; CAP, categories of auditory performance; CC, corpus callosum; CD, congenitally deaf; CI, cochlear implant; CSL, Chinese sign language; CST, corticospinal tract; D, deaf; DS, deaf signing; FA, fractional anisotropy; FOF, fronto-occiptal fasciculus; FOT, fronto-occipital tract; FSL, FMRIB software library; GM, gray matter; HA, hearing aid; HG, Heschl's gyrus; HL, hearing loss; HS, hearing signing; IC, inferior colliculus; IFG, inferior frontal gyrus; IFOF, inferior fronto-occiptal fasciculus; ILF, inferior longitudinal fasciculus; Int/Ext Cap, internal/external capsule; LL, lateral leminscus; LSL, listening and spoken language; LIS, lingua italiana dei segni; MD, mean diffusivity; MGN, medial geniculate nucleus; MTG, middle temporal gyrus; NR, not recorded; PCT, pontine crossing tract; PP, planum polare; PTR, posterior thalamic radiation; RD, radial diffusivity; ROI, region of interest; SCC, splenium of CC; SOF, superior occipial fasciculus; SLF, superior longitudinal fasciculus; SON, superior oliviary nucleus; SPM, statistical parametric mapping; STG, superior temporal gyrus; TB, trapezoid body; TBSS, tract-based spatial statistics; UF, uncinate fasciculus; WM, white matter.