However, in a mouse model of IGF-1 deficiency, that is in IGF-1 knockout mice (Camarero et al., 2001, 2002; Cediel et al., 2006; Riquelme et al., 2010), the causes of SNHL were reported as the loss of spiral ganglion neurons, abnormal myelination of the cochlear nerve, and degeneration of the stria vascularis, based on the results of morphological (Camarero et al., 2001, 2002) and auditory brain stem response studies (Cediel et al., 2006; Riquelme et al., 2010). This evidence concerns the gene IGF1 and hyperinsulinemic hypoglycemia, familial, 4.