To the Editor.鈥�听
We have studied a patient with unusual voluntary nystagmus characterized by exceptionally long duration.
Report of a Case.鈥�听
A 23-year-old engineer could produce nystagmus at will. He had possessed this unusual ability ever since he could remember and he had never needed to practice either to learn or to maintain it. Neither his parents, his grandparents, nor his siblings could produce nystagmus voluntarily. Visual acuity was right 20/20, left 16/20. Fundi were normal. The pupils were normal and reacted promptly to light and to accommodation. Convergence was normal. He had slight strabismus, convergent and sursumvergent. There was no spontaneous horizontal nystagmus, except that when the patient was excited fine horizontal spontaneous nystagmus appeared on forward gaze. Hearing and caloric-induced nystagmus were normal. There were no other neurological abnormalities.He could initiate and terminate nystagmus voluntarily at any time, with eyes opened, closed, or covered. The nystagmus was