Vascular Paramedian Pontine Lesion Associated with Vestirulo-Ocular Disturrances

Abstract

Two cases of a peculiar vestibulo-ocular disturbance are reported. Both showed a crossed hemiplegia, that could be ascribed to a vascular paramedian lesion in the right side of the pons.

There was a left-beating, horizontal nystagmus of the second degree, which appeared spontaneously or in the head-hanging position; no nystagmus was recorded when the eyes were closed. It partly disappeared after a few weeks and was replaced by a directional preponderance to the same side, which was observed in caloric, rotatory and optokinetic tests; a small dose of a barbiturate (Evipan) elicited a nystagmus resembling the spontaneous nystagmus found in the early stages of the disease.

Caloric stimulation of either labyrinth provoked a very slight, if any, nystagmus reaction when the patient's eyes were closed; the same test withthe eyes open resulted in an intense nystagmus. After several months, more normal conditions returned, with a marked caloric nystagmus recordable behind closed eyelids; the nystagmus was now partially suppressed by visual impulses.

Some possible causes of the described bilateral disturbance of the caloric reaction etc. are discussed.