Maturation of the Fast Component of Vestibular Nystagmus During Childhood and Young Adulthood

Abstract

Primary nystagmus was evoked by constant angular acceleration at near-threshold levels (0.2, 0.4, and 0.6°/s²) in 34 normal human subjects (25 children aged 2–11 years and 9 young adults aged 17–21 years). Acceleration was carried out in complete darkness, and with subjects' eyes open. Analysis of response latencies showed that all subjects responded to acceleration magnitude as low as 0.2°/s². A decrease in response latency was associated with an increase in acceleration magnitude, and there was no significant effect of age on response latency or its relationship to acceleration. However, a relationship was found between age and the percentage of trials showing the presence of a set of three successive beats during acceleration: a significant increase in the frequency of such trials occurred with increasing age. The relationship of these findings to brainstem vestibular modulatory mechanisms is discussed.

Key Words:

• nystagmus beat
• nystagmus threshold
• vestibular modulation.