Teaching Video NeuroImage: Bilateral Horizontal Gaze Palsies With Vertical Ocular Dysmetria From a Demyelinating Lesion of the Pontine Tegmentum

Impaired bilateral conjugate horizontal saccades can occur from bilateral abducens nuclear lesions,1 as seen in our patient with multiple sclerosis (Video 1 and Figure). Each abducens nucleus is a horizontal gaze center and innervates the ipsilateral lateral rectus through the abducens fascicle and the contralateral medial rectus via the medial longitudinal fasciculus (Figure). Thus, bilateral lesions of the abducens nuclei cause complete horizontal gaze paresis.