Imaging of Horner's syndrome.

Horner's syndrome, or oculosympathetic paresis, results from interruption of the sympathetic trunk innervation to the eye and presents typically with meiosis, ptosis and facial anhydrosis on the affected side.(1) The pathological process ranges from benign, such as cluster headache, or life threatening, such as lung malignancy. Appropriate imaging requires an anatomical appreciation of the complex and circuitous route the neuronal pathway takes as it passes from the central nervous system to the eye.