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. These nerve fibers are involved with sweating, the pupils in your eyes, and some of the muscles around your eyes.
Damage of the nerve fibers can result from:
- Injury to the carotid artery, one of the main arteries to the brain
- 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
- Injections or surgery done to interrupt the nerve fibers and relieve pain (sympathectomy)
In rare cases, Horner syndrome is present at birth. The condition may occur with a lack of color (pigmentation) of the iris (colored part of the eye).
Horner syndrome is a rare condition that affects the nerves to the eye and face.
Exams and Tests
The health care provider will perform a physical exam and ask about the symptoms.
An eye exam may show:
- Changes in how the pupil opens or closes
- Eyelid drooping
- Red eye
Depending on the suspected cause, tests may be done, such as:
- Blood tests
- Blood vessel tests of the head (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).
The outcome depends on whether treatment of the cause is successful.
There are no direct complications of Horner syndrome itself. But, there may be complications from the disease that caused Horner syndrome or from its treatment.
Symptoms of Horner syndrome may include:
- 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 other symptoms, depending on the disorder that is causing the nerve damage.
Treatment depends on the cause of the problem. There is no treatment for Horner syndrome itself. The provider can tell you more.
When to Contact a Medical Professional
Call your provider if you have symptoms of Horner syndrome.
Baloh RW, Jen JC. Neuro-ophthalmology. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 424.
Thurtell MJ, Rucker JC. Pupillary and eyelid abnormalities. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 18.