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In Reply.—We do not totally disagree with Dr. Coats' statement that high intensity spontaneous nystagmus beats away from the hypoactive caloric side but we have found that there is a sufficient number of variations from that rule to make it less than a sure thing. Dr. Coats has stated in his letter that the right-beating spontaneous nystagmus subgroups of four to five and six to seven degrees per second show statistically greater numbers of hypoactive left calorics (at 0.1% ×2 level), but the same is not true for the left-beating spontaneous nystagmus subgroups. It is this significant discrepancy that makes predicting laterality of the labyrinthine lesion by the direction of spontaneous nystagmus guess work.
The possible statistical error introduced by a higher incidence of left-beating idiopathic spontaneous nystagmus in normal subjects would seem to be nullified or not applicable here, since the patients being considered were not normal.