Horner’s Syndrome: Symptoms, Causes, and Treatment

Horner’s Syndrome, also known as Bernard-Horner syndrome or oculosympathetic palsy, is a condition that affects the sympathetic nervous system.

It causes a triad of ptosis, (the upper eyelid begins to droop on one side of the face), miosis (the pupil constricts, making it smaller than the pupil of the other eye), and anhydrosis (a lack of perspiration, which in Horner’s Syndrome will occur on the affected side of the face).

Horner’s syndrome was first described by Swiss ophthalmologist Johann Friedrich Horner in 1869. It is sometimes associated with migraines and cluster headaches.

It can be acquired through injury, strokes, tumors, disruption of the main artery of the neck, or as an accidental complication of surgery; or in rare cases it may be congenital (present at birth).

13_Horner Syndrome

What Are the Key Symptoms of Horner’s Syndrome?

Symptoms of Horner’s syndrome include:

  • A pupil that is smaller than the pupil of the other eye and does not dilate (enlarge) in dim light
  • Ptosis of the eyelid on the affected side of the face
  • Inverse ptosis (i.e., a raised lower eyelid)
  • Sunken appearance of affected eye
  • A large area of skin that does not perspire on the affected side of the face (anhydrosis)

In small children, Horner’s syndrome can sometimes present additional symptoms:

  • The skin on the affected side of the face may not flush (redden) under conditions that would normally cause flushing (e.g., physical exertion, heat, or emotional stress). In some cases the reverse may occur—the affected side of the face will have a perpetually flushed appearance.
  • The iris of the affected eye may have a lighter color than the unaffected eye (especially in cases of congenital Horner’s syndrome).

How Did I Develop Horner’s Syndrome?

The sympathetic nervous system is responsible for automatic functions in the body, especially those that involve automatic responses to our environment. These functions include regulation of the heartbeat, perspiration, blood pressure, as well as dilation and constriction of the pupil in response to changes in the available light.

Horner’s syndrome occurs when a particular sympathetic nervous-system pathway is damaged. In cases in which this condition is acquired via injury, this damage can be caused by stroke, tumor, or neck trauma, especially if it results in damage to the carotid artery or the jugular vein—the two major blood vessels that run through the neck—or to the brachial plexus, a network of nerves running through the neck.

Rarely, a carotid dissection can occur spontaneously, without a known cause. This happens when blood gets into to the middle layers of the carotid artery, and it should be treated as an emergency. This is typically associated with neck or eye pain.

Congenital Horner’s syndrome can be caused by injury to the neck during birth, by a congenital defect in the aorta (the main artery that extends from the heart into the abdomen), or by a tumor of the nervous system known as a neuroblastoma. In many cases, however, congenital Horner’s is idiopathic, meaning it has no discernible cause.

Risk Factors for Horner’s Syndrome

The incidence of Horner’s syndrome is the same in all races, among all ages, and in both genders. It is not more or less prevalent in any particular part of the world.

How Is Horner’s Syndrome Diagnosed?

If your doctor suspects that you suffer from Horner’s syndrome, he or she will give you a complete physical examination and may refer you to an ophthalmologist for additional testing. Either your primary care doctor or your ophthalmologist will probably administer an eye drop test to determine whether you have nerve damage.

Eye drops will be applied to both eyes that are designed either to constrict or dilate the pupil, and the reaction of the healthy eye will be compared to the reaction of the suspect eye.

Following these examinations, your primary care doctor will evaluate the relative severity and nature of your various symptoms in order to determine whether you are suffering from Horner’s syndrome and what the cause might be.

Imaging tests—CT scans, MRI (magnetic resonance imaging), and x-rays—may also be performed in an attempt to locate the abnormality that is causing your symptoms. Blood and urine tests may be conducted in order to rule out various tumors.

Treatment and Prognosis for Horner’s Syndrome

Because Horner’s syndrome is more a collection of related symptoms than a disease, treatment and prognosis will depend on the cause of the symptoms. Your primary doctor or your ophthalmologist may refer you to a neuro-ophthalmologist, a specialist trained to treat vision problems that arise from conditions affecting the nervous system.


Sources and References:
We have strict guidelines for each of our sources and references. We rely upon vision, eye and medical information from peer-reviewed studies, medical associations and academic research institions.
  • National Institutes of Health https://www.nlm.nih.gov/medlineplus/ency/article/000708.htm
  • American Association for Pediatric Ophthalmology and Strabismus https://www.aapos.org/terms/conditions/27
  • The Mayo Clinic https://www.mayoclinic.org/diseases-conditions/horner-syndrome/basics/definition/con-20034650
  • The New York Times https://www.nytimes.com/health/guides/disease/horner-syndrome/overview.html