A preliminary study of sinusoidal harmonic acceleration test results in 7-12 years old normal children

Sinusoidal harmonic acceleration (SHA) test is one of the most effective and best-tolerated methods to assess vestibular system function, especially horizontal semicircular canal in children. A prerequisite for using this test in children, is the availability of normative data. Despite of the numerous studies related to the SHA in adults, few researches have been documented in children. The aim of this study was to obtain normal values for SHA responses in normal children. In this cross-sectional study, 38 children (20 boys and 18 girls) between 7 to 12 years old (mean age=9.55, SD=1.71) with normal hearing and no history of vestibular dysfunction were enrolled. SHA test was performed in five frequencies (0.01, 0.02, 0.08, 0.16 and 0.32 Hz) and fixation suppression test was performed in two frequencies (0.16 and 0.32 Hz). Parameters of gain, phase and symmetry in SHA test and fixation index (FI) in visual fixation suppression test in each frequency were recorded and compared tow genders. SHA responses and visual fixation suppression results were recorded in all children. Effect of frequency in each parameters of gain and phase were shown to have statistical significant differences, that is with increasing of frequency, gain increases and phase decreases (p≤0/001). In this study normative values for SHA test and visual fixation suppression responses were proposed. These normative data can be used in the assessment of balance disorders and dizziness in school age children.