Horner Syndrome

Horner syndrome is a disorder that affects the eye and surrounding tissues on one side of the face and results from paralysis of certain nerves.

What Is Horner Syndrome?

Horner syndrome is a condition in which nerve fibers from the brain to one side of the face and one eye are damaged. This results in the pupil in the affected eye being abnormally small, or constricted * ; a drooping of the upper eyelid, known as ptosis; and a decreased ability of the affected side of the face to sweat. Horner syndrome is a collection of symptoms that result from another underlying problem rather than being a disease in itself.

How Common Is Horner Syndrome?

Horner syndrome is rare and the diseases that underlie its symptoms range from common to unusual. Common conditions can include underlying migraine or cluster headaches or stroke. Horner syndrome can occur in people of any age.

What Are the Causes of Horner Syndrome?

Horner syndrome can be caused by damage to or interruption in the set of sympathetic nerve * fibers that start in the hypothalamus * of the brain and connect to the face and the eyes. Injury to the sympathetic nerve fibers can be caused by the following:

Rarely, Horner syndrome is present at birth (congenital).

What Are the Signs of Horner Syndrome?

Signs of Horner syndrome include the following:

There also may be symptoms of the problem that is causing Horner syndrome. For example, if Horner syndrome is associated with a tumor in the brain, there may be symptoms related to the tumor.

What Is the Treatment for Horner Syndrome?


Diagnosis of Horner syndrome is based on the patient's reported medical history and observation of the eye, specifically noting changes in how the pupil opens (dilates) and closes (constricts), and drooping of the upper eyelid. Laboratory and other diagnostic studies may be done to determine the cause of the syndrome. For example, a chest x-ray may be done to determine if there is a tumor at the top of the lung causing the syndrome. Sometimes, the doctor orders a computed tomography (CT) scan of the head, especially if stroke might be the cause of Horner syndrome.


There is no specific treatment for Horner syndrome. Treatment is specific to the condition that is causing the disorder. For example, if the cause of the Horner syndrome is a stroke, then the treatment plan is directed toward the stroke.

A person with Horner syndrome should take precautions to protect the eye. For example, if the drooping eyelid results in the eye not closing completely, eyes may become dry. In that case, lubricating eyedrops may be recommended.


Books and Articles

Waldman, Steven D. Atlas of Common Pain Syndromes. 3rd ed. Philadelphia: Saunders, 2012.


Genetics Home Reference. “Horner Syndrome.” https://ghr.nlm.nih.gov/condition/horner-syndrome (accessed March 24, 2016).

MedlinePlus. “Horner Syndrome.” U.S. National Library of Medicine. https://www.nlm.nih.gov/medlineplus/ency/article/000708.htm (accessed June 13, 2016).

Merck Manual: Consumer Version. “Horner Syndrome.” https://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/autonomic-nervous-system-disorders/horner-syndrome (accessed March 24, 2016).


National Organization for Rare Disorders. 55 Kenosia Ave., Danbury, CT 06810. Telephone: 203-744-0100. Website: https://rarediseases.org (accessed July 6, 2015).

* sympathetic nervous system. is the system of nerves that prepares the body for stress or action by speeding up the heart and breathing rates and raising the blood pressure.

* constricted pupil is when the pupil of the eye becomes smaller, usually in response to light, but sometimes because of certain medications or diseases.

* hypothalamus (hy-po-THAL-uhmus) is a structure located deep within the brain that regulates automatic body functions such as heart rate, blood pressure, temperature, respiration, and the release of hormones.

* migraine (MY-grain) is a type of headache characterized by a throbbing or pulsating sensation, affecting one side of the head, and often accompanied by nausea and disturbed vision.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)