Correlation between vestibular and cochlear measures in internal ear disorders

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 quantify 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, coupled with the development of electronystagmography and the value of a permanent record of the caloric responses, led to the widespread use of the 'slow-phase velocity' measurement of induced nystagmus, as the most commonly used parameter for 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 information. The strengths and shortcomings of these two parameters and their relative values are reviewed.

Correlation between velocity step and caloric response parameters

The correlation between velocity step (VS) and caloric response parameters was studied in a series of several hundred patients who underwent a neuro-otological examination. The VS parameters initial velocity (V in degree/s), time constant (T in s) and Gesamtamplitude G ( = VT in deg) were all significantly correlated with the caloric response parameters. The highest correlation coefficients were associated with G.