The maturation of vestibular nystagmus in infancy and childhood.

The displacements, durations, and velocities of the slow and fast components of both the primary and secondary nystagmus induced by constant angular acceleration were measured in 46 normal children 1 month to 11 years old. There were significant changes in nystagmus parameters in respect to maturation. The young infant had larger amplitude, higher velocity beats than the older child during both the primary and the secondary nystagmus. Parameters describing both the primary and the secondary nystagmus reached their peak values and terminated earlier in the infant than in the older child. Although the slow component velocity during secondary nystagmus was much slower than during the primary nystagmus at all ages, the secondary nystagmus/primary nystagmus ratio was significantly greater in early infancy. Thus, in infancy, as compared with later childhood, the vigor of the secondary nystagmus was disproportionately greater than the primary nystagmus. These results were discussed in relation to the maturation both of vestibular responsiveness and of vestibular adaptation.