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  • Updated 01.11.2017
  • Released 08.28.1998
  • Expires For CME 01.11.2020

Horner syndrome


This article includes discussion of Horner syndrome, Bernard syndrome, Bernard-Horner syndrome, Claude Bernard syndrome, Horner’s syndrome, Horners syndrome, and subclinical Horner syndrome. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


The authors provide an updated clinical review of Horner syndrome. The most current recommendations regarding pharmacologic diagnosis and radiographic evaluation are highlighted. Important issues regarding the evaluation of Horner syndrome in children are also reviewed.

Key points

• Horner syndrome is caused by an interruption of sympathetic nerves to the head, eye, and neck.

• The hallmark of Horner syndrome is ptosis and miosis on the same side.

• When Horner syndrome is suspected, pharmacologic testing with cocaine or apraclonidine should be performed to confirm the diagnosis as there are other causes of ptosis and miosis.

• Use of hydroxyamphetamine to localize the lesion is no longer recommended because it is unreliable.

• The use of selective or nonselective imaging to evaluate for an underlying cause is based on the presence of localizing clinical features.

Historical note and terminology

Horner syndrome is an eponym used to describe the clinical triad of ptosis, miosis, and anhidrosis caused by interruption of the ipsilateral first-, second-, or third-order sympathetic neurons to the head, eye, and neck. It is named after the Swiss ophthalmologist Johann Friedrich Horner, but he was not the first to describe this syndrome. In 1727, Pourfour du Petit reported ptosis, miosis, and enophthalmos after cutting the vagosympathetic nerve trunk in dogs (73). Edward Selleck Hare reported similar signs in a published letter to the London Medical Gazette in 1838 (38), in which he described a 40-year-old man with ptosis, miosis, and arm dysesthesias from a tumor involving the structures of the left neck. However, he was unable to relate the eye findings to the structural involvement by the tumor.

Although other physiologists such as Ruete and Budge worked to establish the sympathetic innervation of the eye and pathways of these fibers, additional animal experiments in rabbits by Claude Bernard, published in 1852, finally led to the most complete description of the effects of severing the cervical sympathetic fibers and the first hypothesis that sympathetic nerves regulated the vasomotor response in blood vessels (08; 28; 70; 74). Given his important contribution, the syndrome is sometimes called Bernard syndrome or Bernard-Horner syndrome.

In 1864, S Weir Mitchell described the first full human account of ocular and facial findings attributed to injury of the sympathetic trunk in a 24-year-old man with a gunshot wound to the neck. It was not until 1869 that Johann Friedrich Horner famously reported the findings of ptosis, miosis, and enophthalmos in a 40-year-old peasant woman (39). He also observed increased skin temperature and dryness of the ipsilateral face. He pharmacologically confirmed the impairment of sympathetic innervation to the eye after noting poor dilation of the affected pupil following instillation of atropine and preserved pupillary constriction to the parasympathomimetic agent calabar.

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