Vertical Gaze Ophthalmoplegia and the Vascular Anatomy of the Midbrain and Diencephalon

Henri Parinaud, in 1883, described a patient with paralysis of elevation and convergence and in the same paper reported a patient with total vertical gaze paralysis. The latter patient, in addition, had a complete paralysis of convergence with small pupils, right larger than left, that did not react to light or to a near target. Horizontal gaze was normal except for a slight conterc-lockwise rotary movement during left lateral gaze. He postulated ischemic infarction as the mechanism of the second patient's deficit but incorrectly localized the lesion in both cases to the pons. Since Parinaud's description there have been numerous reports of vertical gaze ophthalmoplegia (VGO) and much has been learned about the physiology of vertical gaze