Table 3.
Mean volume of individual CN subdivisions in neonatally deafened, 30-day deafened and normal animals studied at the ages of 8 weeks and 8 months (ipsilateral and contralateral to the electrically stimulated cochlea).
| Group | AVCN, mm3 mean ±SD |
% of normal |
p-value1 neonatally vs. 30-day deafened |
PVCN, mm3 mean ±SD |
% of normal |
p-value1 neonatally vs. 30-day deafened |
DCN, mm3 mean ±SD |
% of normal |
p-value1 neonatally vs. 30-day deafened |
|---|---|---|---|---|---|---|---|---|---|
| 8 weeks of age | |||||||||
| Neonatally deafened (n=5) | 3.79±0.70** | 65% | } 0.009 | 1.86±0.34** | 63% | } 0.007 | 2.96±0.52** | 68% | ns |
| 30-day deafened (n=6) | 4.94±0.51 | 85% | 2.45±0.39 | 83% | 3.54±0.19 | 82% | |||
| Normal, 8 weeks (n=5) | 5.84±0.83 | -- | 2.96±0.24 | -- | 4.34±0.71 | -- | |||
|
| |||||||||
| 8 months of age: Contralateral to the CI | |||||||||
| Neonatally deafened (n=6) | 5.26±0.67** | 57% | } 0.048 | 2.65±0.35** | 67% | } 0.013 | 4.15±0.63** | 74% | ns |
| 30-day deafened (n=6) | 6.36±0.32** | 69% | 3.45±0.38 | 88% | 5.01±0.45 | 89% | |||
|
| |||||||||
| 8 months of age: Ipsilateral to the CI | |||||||||
| Neonatally deafened (n=6) | 5.52±0.93** | 60% | } 0.04 | 2.75±0.38** | 70% | ns (0.06) | 4.47±0.62* | 80% | ns |
| 30-day deafened (n=6) | 6.77±0.91** | 74% | 3.32±0.44 | 84% | 4.98±0.60 | 89% | |||
|
| |||||||||
| Adult normal | |||||||||
| Normal | 9.18±1.61 | -- | 3.93±0.65 | 5.60±0.52 | -- | ||||
P<0.001 for comparisons with age-matched normal animals;
P<0.05 vs. age-matched normal animals; ns – “not significant”, P>0.05
Logarithmic transformation of the data was performed before ANOVA to adjust for heterogeneous variances
A significant group effect of the age at onset of deafness on the volumes of the CN subdivisions was observed in both age groups (two-way ANOVA, p<0.001, no significant interaction). Post-hoc multiple comparisons between 30-day deafened and neonatally deafened groups showed a significant difference in the AVCN and PVCN volumes, but not in the DCN. There was no significant effect of electrical stimulation (CN ipsilateral vs. CN contralateral to the electrically stimulated cochlea, two-repeated measures ANOVA, stimulation and onset of deafness as factors) either in the neonatally deafened (p=0.06 for the group effect of stimulation) or in the 30-day deafened group (p=0.49 for the group effect of stimulation).