Clinico-pathologic Correlation of Supranuclear Upgaze Paresis in Idiopathic Parkinson's Disease

Supranuclear control of vertical eye movements lies in the mesencephalic reticular formation. The rostral intersitial nucleus of the medial longitudinal fasciculus (riMLF) contains the vertical burst neurons that project predominantly to the ipsilateral oculomotor nerve nuclei. The frontal eye fields, the vestibular complex and the paramedian pontine reticular formation send projections to the riMLF. Lesions involving the riMLF can impair both upward and downward eye movements. In addition the intersitial nucleus of Cajal (INC) , the nucleus of Darkschewitsch (nD), the nucleus of the posterior commissure and adjacent reticular formation are involved in vertical eye movements. The neurons of the INC project to the contralateral superior rectus and inferior oblique subnuclei of III via the posterior commissure. Therefore, may explain why lesions of the posterior commissure selectively impair upward gaze. The role of the nD is less clear, since reports of lesions impairing supraduction involving nD also involve her mesencephalic nuclei.