Diagnosing Horner's syndrome.

The diagnosis of Horner's syndrome is divided into two stages: (1) the recognition of the sympathetic deficit, and (2) the localization of the lesion. The second step is of vital importance in the management of the patient with Horner's syndrome. If the lesion is preganglionic, the risk of malignancy is high; the patient should have cervical spine and chest roentgenograms (PA, lateral and apical lordotic) and perhaps a referral to a surgeon. If the lesion is postganglionic, it is most likely a benign vascular headache syndrome and the patient should go to a neurologist.