Horner syndrome is a combination of signs and symptoms caused by abnormalities in the oculosympathetic pathway. Typically, patients present with ipsilateral miosis, ptosis, and anhidrosis. Imaging the oculosympathetic pathway is complex because of its extensive course, need for targeted protocols, and the wide range of pathology that can cause it. For this document, we focus our attention on workup guidelines based on clinical features: 1) acuity (acute, nonacute including chronic, insidious, an…