Abstract
The maximum velocity of the slow phase of caloric nystagmus was mesured from the electronystagmograms of 354 patients with various kinds of inner ear disturbances. The percentages of canal paresis and directional preponderance were calculated according to Jongkees' formula. The authors set the normal limits of 'canal paresis' (CP) and of 'directional preponderance' (DP) at ± 26% and ± 29%, respectively. DP was found in28 patients and DP+ CP in 59. The calorigrams of these 87 patients were classified into three types : (1) Both caloric nystagmuses directed to the right side (induced by a hot stimulus on the right side and a cold stimulus on the left side) were larger than both caloric nystagmuses directed to the left side (induced by a hot stimulus on the left side and a cold stimulus on the right side) and vice versa (28 patients). (2) One caloric nystagmus directed to the right side (induced by a hot stimulus on the right side or a cold stimulus on the left side) was larger but the other caloric nystagmus directed to the right side (induced by a hot stimulus on the right side or a cold stimulus on the left side) was smaller than one or both of the two caloric nystagmuses directed to the left side (induced by a hot stimulus on the left side and/or a cold stimulus on the right side) and vice versa (46 patients). (3) Because of severe canal paresis on one side, one caloric nystagmus was much longer than the other caloric nystagmus on the unaffected side (13 patients).
