Eye movement findings for the lesion localization diagnosis

Abstract

Monocular eye movement abnormalities and strabismus are caused by a lesion involving brainstem ocular motor nucleus (such as the oculomotor nucleus and abducens nucleus) and/or its afferent/efferent fibers (such as the medial longitudinal fasciculus). On the other hand, conjugate eye movement abnormalities are explained by a disorder of the saccadic or vestibular neural system. The horizontal saccadic system consists of the frontal eye field, and contralateral paramedian pontine reticular formation and abducens nucleus, and the horizontal vestibular system consists of the vestibular nucleus (lateral semicircular canal), cerebellum, and contralateral abducens nucleus. The vertical saccadic system originates from the rostral interstitial nucleus of medial longitudinal fasciculus, and the vertical vestibular system originates from the vestibular nucleus (anterior and posterior semicircular canals). Torsional eye movements are always involved in the vertical saccadic and vestibular systems.