Horner syndrome: Causes, Symptoms, Diagnosis and Treatment

She also called oculosympathetic paresis.

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

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


Horner’s syndrome may result from various factors, including dissection of the carotid artery, the development of a neck or chest cavity tumor, particularly 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 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 brain region that controls the sympathetic nervous system (hypothalamus).


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

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

In other cases, some clinical researchers believe 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 Horner’s syndrome is onset 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 lesion site.

In addition to a complete physical examination, the pharmacological tests are a valuable tool that can help with the diagnosis and the location of the injuries that cause the disorder 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 severe disorders 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 containing 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. Surgical removal of the lesion or growth may be appropriate in some cases.

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