Gross motor development
Fig. 1 shows the comparison of the mean gross motor development timing between the IEM and control groups. The mean ages of head control and independent walking in the IEM group were 3.73±0.86 months and 15.39±4.5 months, respectively. The independent-samples T-test showed that the balance development of children with IEMs was delayed when compared to the control group (p =0.02).
Additionally, two children in the IEM group presented with vertigo and slight unsteadiness postoperatively, but all symptoms resolved within 48 h. The impaired otolith function did not correlate with vertigo symptoms (logistic regression analysis, p >0.05).
To estimate the effect of otolith dysfunction on the development of gross motor function, we compared the age of acquiring gross motor skills with the results of both the cVEMP and oVEMP test (Table 2). In terms of acquiring independent walking, children who showed abnormal cVEMP responses were significantly more delayed compared with those who showed normal responses (p =0.017). There were no significant differences in the age of acquiring gross motor abilities between children with abnormal oVEMP and normal response (p >0.05).
All patients and a total of 156 ears were tested for cVEMP, whilst 96 ears from 48 patients underwent oVEMP testing before surgery. The chi-squared test showed significant differences in the response rates of cVEMP (X2 =4.768, p =0.003) and oVEMP (X2 =4.408, p =0.003) between the IEM and control groups. There was no statistical difference in each parameter between the two groups by the independent samples t-test (Tables 3 and 4).