A Study of Non-Convective Factor of Caloric Nystagmus in Relationship between Head Position and Maximal Slow Phase Eye Velocity / 대한이비인후과학회지

ABSTRACT

Background and OBJECTIVE: There are strong evidences that the caloric nystagmus may be due to non-convective factors in addition to the widely accepted Barany's convection theory. The influence of non-convective factor on the caloric nystagmus was interpreted by measuring the maximal slow phase eye velocity according to the head position. MATERIALS AND METHODS: In 18 normal ears, the maximal slow phase eye velocity of the cold caloric nystagmus was measured at five (-15degrees, 05degrees, 305degrees, 455degrees, 605degrees) different head positions. RESULTS: The sine value of the angle of the lateral semicircular canal (LSCC) plotted against the maximal slow phase velocity showed linear relationship without crossing the zero point in linear regression analysis. CONCLUSION: Maximal slow phase eye velocity shows linear relationship with the sine value of the angle of the LSCC. Compared with the curve expected by the convective factor, the curve in this study was biased by a constant amount (about 20%), which can be attributed to non-convective factor.