Neuroanatomical correlates of selective downgaze paralysis

A 56-year-old woman had the sudden onset of a selective paralysis of downgaze associated with a partial third nerve paralysis on the right. On numerous examinations over the ensuing 3 and 3/4 years, these deficits were observed to persist. At autopsy, bilateral somewhat asymmetrical cavitated lesions were seen in the region of the thalamo-mesencephalic junction. Because this patient's selective downgaze paralysis was permanent, it is concluded that the supranuclear neural elements mediating downgaze are situated within the confines of these lesions. A consideration of the present case together with previous reports of selective vertical gaze paralysis permits the relevant region to be further localized to an area extending from the oculomotor nucleus to the rostral pole of the red nucleus and immediately dorsomedial to the latter. This is likely to be the location of the human analogue of the monkey "nucleus of the prerubral fields", a supranuclear structure which is thought to mediate vertical gaze and especially downgaze.