Horner syndrome is a rare condition that affects the nerves to the eye and face.

Horner syndrome can be caused by any interruption in a set of nerve fibers that start in the part of the brain called the hypothalamus and travel to the face and eyes.

Sympathetic nerve fiber injuries can result from:

• Injury to one of the main arteries to the brain (carotid artery)
• Injury to nerves at the base of the neck called the brachial plexus
• Migraine or cluster headaches
• Stroke, tumor, or other damage to a part of the brain called the brainstem
• Tumor in the top of the lung

Rarely, Horner syndrome may be present at birth (congenital). The condition may occur with a lack of color (pigmentation) of the iris (colored part of the eye).

• Decreased sweating on the affected side of the face
• Drooping eyelid (ptosis)
• Sinking of the eyeball into the face
• Small (constricted) pupil (the black part in the center of the eye)

There may also be symptoms of the disorder that is causing the problem.

An eye examination may show:

• Changes in how the pupil opens or closes
• Eyelid drooping
• Red eye

A complete medical and nervous system (neurological) examination can show whether any other parts of the body are affected.

Other tests may include:

• Blood tests
• Blood vessel tests (cerebral angiogram, CT angiogram, or MR angiogram
• Chest x-ray or chest CT scan
• MRI or CT scan of the brain
• Spinal tap (lumbar puncture)

You may need to be referred to a doctor who specializes in vision problems related to the nervous system (neuro-ophthalmologist).

Treatment depends on the cause of the problem. There is no treatment for Horner syndrome itself.

The outcome depends on whether treatment of the cause is successful.

There are no direct complications of Horner syndrome itself. However, there may be complications from the disease that caused Horner syndrome or from its treatment.

Call your health care provider if you have symptoms of Horner syndrome.

Baloh RW. Neuro-ophthalmology. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 450.

Saper CB. Autonomic disorders and their management. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 445.