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Horner syndrome

Sachin Kedar, MD
Valérie Biousse, MD
Nancy J Newman, MD
Section Editor
Paul W Brazis, MD
Deputy Editor
Janet L Wilterdink, MD


Horner syndrome is a classic neurologic syndrome whose signs include miosis, ptosis, and anhidrosis. Also called oculosympathetic paresis, a Horner syndrome can be produced by a lesion anywhere along the sympathetic pathway that supplies the head, eye, and neck. Causes range from benign to serious, requiring a methodological approach to diagnostic evaluation. The differential diagnosis also differs in children and adults, leading to differences in the diagnostic approach.

This topic reviews Horner syndrome. Other causes of anisocoria and ptosis are reviewed separately. (See "Approach to the patient with anisocoria" and "Overview of ptosis".)


Horner syndrome can result from a lesion anywhere along a three-neuron sympathetic (adrenergic) pathway that originates in the hypothalamus (figure 1):

The first-order neuron descends caudally from the hypothalamus to the first synapse, which is located in the cervical spinal cord (levels C8-T2, also called ciliospinal center of Budge).

The second-order neuron travels from the sympathetic trunk, through the brachial plexus, over the lung apex. It then ascends to the superior cervical ganglion, located near the angle of the mandible and the bifurcation of the common carotid artery.

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Literature review current through: Nov 2017. | This topic last updated: Jul 14, 2015.
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