Among several sources of error on the caloric test, the following which may have relevance to the diagnosis of canal paresis were discussed. First, with the alternate cold and hot caloric test one cannot detect canal paresis of one labyrinth unless the response obtained on that side is abnormally weak. Second, the majority of cases showing directional prepon-derance on the alternate cold and hot caloric test revealed spontaneous nystagmus in the spontaneous- and the evoked-nystagmus tests using electronystagmography. Thus the combination of these tests and the caloric test using the cold water irrigation alone may afford the diagnosis of canal paresis, because the influence of directional preponderance can be eliminated. Third, the use of Frenzel glasses and the eye opening in darkness are recommended as the condi-tions for observing and recording caloric nystagmus respectively. Furthermore, application of considerably intense caloric stimulation is recommended to avoid false positive interpretation of canal paresis.
