About horner's syndrome

What is horner's syndrome?

Horner syndrome is a relatively rare disorder characterized by a constricted pupil (miosis), drooping of the upper eyelid (ptosis), absence of sweating of the face (anhidrosis), and sinking of the eyeball into the bony cavity that protects the eye (enophthalmos). These are the four classic signs of the disorder.

The congenital, and more rare, form of Horner syndrome is present at birth but the cause is not known. Most often, Horner syndrome is acquired as a result of some kind of interference with the sympathetic nerves serving the eyes. The underlying causes can vary enormously, from a snake or insect bite to a neck trauma made by a blunt instrument.

What are the symptoms for horner's syndrome?

A notable difference in pupil size between the two eyes (anisocoria) symptom was found in the horner's syndrome condition

Signs and symptoms, particularly ptosis and anhidrosis, may be subtle and difficult to detect.


Additional signs and symptoms in children with Horner syndrome may include:

  • Lighter iris color in the affected eye of a child under the age of 1
  • Change in color on the affected side of the face that would typically appear from heat, physical exertion or emotional reactions

What are the causes for horner's syndrome?

Horner syndrome is caused by damage to a certain pathway in the sympathetic nervous system. The sympathetic nervous system regulates heart rate, pupil size, perspiration, blood pressure and other functions that enable you to respond quickly to changes in your environment.

The nerve pathway affected by Horner syndrome is divided into three groups of nerve cells (neurons).

First-order neurons

This neuron pathway leads from the hypothalamus at the base of the brain, passes through the brainstem and extends into the upper portion of the spinal cord. Problems in this region that can disrupt nerve function related to Horner syndrome include:

  • Stroke
  • Tumor
  • Diseases that cause the loss of the protective sheath on neurons (myelin)
  • Neck trauma
  • Cyst in the spinal column (syringomyelia)

Second-order neurons

This neuron path extends from the spinal column, across the upper part of the chest and into the side of the neck. Causes related to nerve damage in this region may include:

  • Lung cancer
  • Tumor of the myelin sheath (schwannoma)
  • Damage to the main blood vessel leading from the heart (aorta)
  • Surgery in the chest cavity
  • Traumatic injury

Third-order neurons

This neuron path extends along the side of the neck and leads to facial skin and muscles of the iris and eyelids. Nerve damage in this region may be associated with the following:

  • Damage to the carotid artery along the side of the neck
  • Damage to the jugular vein along the side of the neck
  • Tumor or infection near the base of the skull
  • Migraines
  • Cluster headaches, a disorder that results in cyclical patterns of severe headaches


The most common causes of Horner syndrome in children include:

  • Injury to the neck or shoulders during delivery
  • Defect of the aorta present at birth
  • Tumor of the hormonal and nervous systems (neuroblastoma)

Unknown causes

In some cases, the cause of Horner syndrome cannot be identified. This is known as idiopathic Horner syndrome.

What are the treatments for horner's syndrome?

There's no specific treatment for Horner syndrome. Often, Horner syndrome disappears when an underlying medical condition is effectively treated.

What are the risk factors for horner's syndrome?

Cause of horner's syndrome

Carotid artery dissection, the emergence of tumors in the neck or chest cavity, particularly neuroblastomas and tumors of the upper part of the lung (Pancoast tumor), the emergence of lesions in the midbrain, brain stem, upper spinal cord, neck, or eye orbit, inflammation or growths affecting the lymph nodes of the neck, and/or surgery or other types of trauma to the neck or upper spinal cord are just a few possible causes of horner's syndrome.

Risk factors involved in horner's syndrome

1. The combination of the genes for a specific trait found on the chromosomes inherited from the mother and father determines the presence of genetic illnesses.

2. Every person carries a few faulty genes. Consanguineous parents are more likely than unrelated parents to share a defective gene, which raises the likelihood that their offspring may develop a recessive genetic condition.

3. When just one copy of a defective gene is required for the disease to manifest, dominant genetic diseases result. The faulty gene may be brought on by a new mutation (gene alteration) in the sick person, or it may be inherited from either parent. Regardless of the sex of the offspring, there is a 50% chance that the faulty gene will be passed from the affected parent to their offspring throughout each pregnancy.

4. Horner's syndrome is an uncommon condition that can afflict both sexes equally, manifest itself at any age, in any ethnic group, and occur anywhere in the world.

A persistently small pupil (miosis),A notable difference in pupil size between the two eyes (anisocoria),Little or delayed opening (dilation) of the affected pupil in dim light,Drooping of the upper eyelid (ptosis),Slight elevation of the lower lid, sometimes called upside-down ptosis,Sunken appearance of the affected eye,Little or no sweating (anhidrosis) on the affected side of the face
Disruption of a nerve pathway from the brain to the head and neck that affects the face and eye on one side of the body,Decreased eye pupil size

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