Vestibular Reactivity in Cases of Congenital Nystagmus and Blindness

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Abstract
Twenty cases of congenital idiopathic nystagmus and twenty-one cases of blindness without complicating disabilities were all irrigated with water of 30° and 44°C in the right and the left ear for 40 seconds. The resulting vestibulo-ocular and vestibulo-spinal reactions were recorded and the experienced vertigo noted. From earlier examinations it was known that none of these cases of congenital nystagmus had any vestibulo-ocular reactions. Of the blind subjects, 12 cases had no vestibulo-ocular reflexes and 9 had weak ones. All cases of congenital nystagmus and blindness had preserved vestibulospinal reactions (laterotorsion). When comparing laterotorsion and vertigo in the two materials with the same qualities in a normal material it was shown that the vestibulo-spinal reactions were smaller in cases of blindness with absent vestibulo-ocular reactivity than in the other groups and that the vertigo was less in congenital nystagmus than in the other groups. The similarity of the labyrinthine reactivity pattern in cases of congenital nystagmus and of blindness to that in normals, habituated by repeated calorizations, was pointed out. The possibility that the vestibulo-ocular areflexia in congenital nystagmus and blindness might be caused by habituation was discussed.