Objective: The purposes of this study were to review the anatomy of the oculosympathetic pathway, to describe the clinical characteristics of the three types of Horner syndrome, and to illustrate underlying pathologic features with an emphasis on neuroimaging strategies based on three symptom complexes.
Conclusion: Horner syndrome results from interruption of the oculosympathetic pathway and is usually associated with unique clinical features classified into central, preganglionic, and postganglionic types according to the anatomic location of the underlying pathologic process.