Horner syndrome: Causes, Symptoms, Diagnosis and Treatment

Also called oculosympathetic paresis.

It comprises a constellation of clinical signs that include the classic triad of ptosis, miosis and anhidrosis. It is the result of an injury to the sympathetic pathways that irrigate the head and neck region.

The causes of Horner’s syndrome vary according to the age of the patient and the site of the injury. A rapid assessment is necessary to detect and treat life-threatening conditions.


Horner’s syndrome may be the result of a variety of factors, including dissection of the carotid artery ; the development of a tumor in the neck or chest cavity, particularly a neuroblastoma and a tumor of the upper part of the lung (Pancoast tumor).

As well as the development of a lesion in the midbrain, brainstem, upper spinal cord, neck or eye socket; inflammation or growths that affect the lymph nodes of the neck; and / or surgery or other forms of trauma to the neck or upper spinal cord.

In most cases, the physical findings associated with Horner’s syndrome develop due to an interruption of the sympathetic nerve supply to the eye due to injury or growth.

The lesion develops somewhere along the way from the eye to the region of the brain that controls the sympathetic nervous system (hypothalamus).

The sympathetic nervous system (together with the parasympathetic nervous system) controls many of the involuntary functions of the glands, organs, and other parts of the body.

Some cases of Horner syndrome occur for no other apparent reason or cause unknown.

In other cases, some clinical researchers believe that the disorder can be inherited as an autosomal dominant genetic trait.

Genetic diseases depend on the combination of genes for a particular trait found in the chromosomes received from the father and the mother.

Signs and symptoms of Horner syndrome

The characteristic physical signs and symptoms associated with Horner’s syndrome usually affect only one side of the face (unilateral). These include:

  • False upper eyelid ptosis.
  • Lost anhidrosis of sweating on the same side of the face (ipsilateral) as the affected eye.
  • Miosis or retraction of the eyeball.
  • Eye sunk or injected in blood.
  • Headaches.

If the onset of Horner’s syndrome is before two years of age, the colored portions of the eyes (iris) may be of different colors (heterochromia iridis).

In most cases, the iris on the affected side has no color (hypopigmentation).


Physicians who diagnose a possible Horner syndrome should carefully evaluate the patient to detect other neurological manifestations that can help confirm the diagnosis and locate the site of the lesion.

In addition to a complete physical examination, the pharmacological tests are a valuable tool that can help not only with the diagnosis but also with the location of the injuries that cause the disorder in order to direct the tests and the management of the patient.

The diagnosis can be determined by pharmacological tests combined with imaging techniques, such as:

  1. Eye drop tests
  2. Magnetic resonance or computed tomography. Magnetic resonance imaging (MRI) or computed tomography (CT) scans of the brain, spinal cord, chest, or neck are often needed to detect tumors and other serious disorders that may be altering the nerve fibers that connect the brain and eye .

To confirm the diagnosis of Horner’s syndrome and determine where the problem is, doctors perform a test in two parts:

  1. Apply eye drops that contain small amounts of cocaine or another medicine (apraclonidine) to both eyes.
  2. If Horner syndrome is likely, doctors do another test 48 hours later. Apply drops of hydroxyamfetamine in both eyes.


There are no specific treatments for Horner’s syndrome.

The best way to help with your symptoms is to treat the health problem that caused them. In some cases, surgical removal of the lesion or growth may be appropriate.

Radiation and chemotherapy may be beneficial for patients with malignancies. Genetic counseling can be beneficial for patients and their families if they have the genetic form of this disorder.