COMPARISON OF ASSESSMENT OF CALORIC NYSTAGMUS BY OBSERVATION OF DURATION AND BY ELECTRONYSTAGMOGRAPHIC MEASUREMENT OF SLOW-PHASE VELOCITY

The 'duration' of induced nystagmus was the first parameter used to qu antify vestibular function during caloric testing. However, later work suggested that there was a poor correlation between this measure and the physiological events occurring during caloric testing. This, coupl ed with the development of electronystagmography and the value of a pe rmanent record of the caloric responses, led to the widespread use of the 'slow-phase velocity' measurement of induced nystagmus, as the mos t commonly used parameter far assessment of the caloric test. Despite a wealth of literature, the 'best' parameter for measuring vestibular function using the caloric test remains undefined and the duration and slow-phase velocity parameters appear to provide different informatio n. The strengths and shortcomings of these two parameters acid their r elative values are reviewed.