[Pharmacological localization of Horner's syndrome. Case report].

Horner's syndrome is derived from an interruption of the sympathetic pathway at any point along its course between the hypothalamus and the orbit. This pathway is generally considered to consist of three neurons. It had been suggested that the pupillary response to various pharmacologic agents will aid in localizing the lesioned neuron in the sympathetic pathway. We had the opportunity to observe a patient who developed Horner's syndrome as a consequence of pulmonary apex adenocarcinoma. Clinical, radiologic and pharmacologic studies are presented. The methods of pharmacologic localization are discussed.