Korean J Otolaryngol-Head Neck Surg.  1999 Oct;42(10):1225-1229.

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

• Byun SW
• Cho YH
• Park SI
• Hong SK
• Kim CD

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.

Keyword

Convection theory; Caloric nystagmus; Maximal slow phase eye velocity; Non-convective factor

MeSH Terms

Bias (Epidemiology)
Convection
Ear
Head*
Linear Models
Nystagmus, Physiologic*
Semicircular Canals