Vertical gaze: Clinical and experimental considerations with particular reference to oblique movements

Abstract

On correlating the clinicopathologic data in man with those in the experimental monkey one may conclude that the syndrome of paralysis of upward gaze is due to involvement of the mesencephalon, while the syndrome of paralysis of downward gaze is due to implication of a more rostral area in the diencephalon. In instances of paralysis of both upward and downward gaze the pathology is at the mesodiencephalic junction. Paralysis of downward gaze is rarely associated with impairment of pupillary reflexes, whereas paralysis of upward gaze is frequently accompanied by impairments of efferent pupillary responses, eyelid retraction and, less frequently, by binocular adductive saccades. In man, paralysis of upward gaze is commonly caused by lesions, such as tumor, vascular disease or aqueductal stenosis, localized within the mesodiencephalon. Isolated paralysis of downward gaze is rare in cases of tumor and found predominately in patients with vascular disease. In patients with diffuse involvement of the brain, such as lysosomal storage disease or progressive supra-nuclear palsy, paralysis of vertical gaze is common and almost always bidirectional with impairment of downward preceding that of upward gaze. The defects in saccades in all of these cases precede impairment of pursuit or smooth movements. Obliquely induced eye movements, in patients or monkeys with paralysis of vertical (upward or downward) gaze. resulted in horizontal nystagmus. Binocular adductive saccades and questionable 'retractory nystagmus' may be found in patients with paralysis of upward gaze due to tumor or vascular lesion of the mesodiencephalic area or in cases of acute distention of the oral portion of the aqueduct of Sylvius. The binocular adductive saccades. which can be induced by attempts to look upward. or during induction of ocular gaze nystagmus in an upward or obliquely upward direction (with optokinetic or vestibular stimuli). remain unexplained.