Nicotine-induced nystagmus: three-dimensional analysis and dependence on head position.

Two- and three-dimensional analyses of nicotine-induced eye movements were performed in 53 subjects to evaluate whether they were primarily of vestibular or ocular motor origin. Nicotine-induced nystagmus was detected in 27 subjects (51%); in 25 of these (93%) it was modulated by otolith input. Three-dimensional analysis of nicotine-induced nystagmus revealed that it violates Listing's law. Taken together, these findings suggest that nicotine induces an imbalance in the vestibulo-ocular reflex.