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Horner's Syndrome: Causes, Symptoms, and Treatments

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Horner’s syndrome, also known as oculosympathetic palsy or Bernard-Horner syndrome, is a relatively rare condition that affects the eyes and part of the face. It occurs due to a disruption of the pathway of the sympathetic nerves that connect the brain stem to the eyes and face. These nerves control involuntary functions, such as dilation and constriction of the pupils of the eye and perspiration.

Usually, symptoms associated with Horner’s syndrome affect only one side of the face. Horner’s syndrome can occur in people of all ages and both sexes. It can affect people of all races and ethnic groups.

The symptoms associated with Horner’s syndrome, in and of themselves, generally do not cause significant problems with a person’s health or vision. However, they can indicate the presence of an underlying health problem that may be very serious.

Horner’s syndrome

What are the types of Horner’s syndrome?

Three different nerve pathways may be involved in Horner’s syndrome. The nerves from the brain do not travel along a direct path to the eyes and face. They travel along three paths and disruption may occur in any of these pathways.

First order (central) Horner's syndrome — The nerves from the hypothalamus in the brain lead down through the brain stem and spinal cord to the chest. Damage or obstruction of this nerve pathway may occur due to:

  • Sudden interruption of the blood flow to the brain stem
  • Tumor of the hypothalamus
  • Spinal cord lesions

Second order (preganglionic) — The second stage of the nerve pathway leads from the chest to the top of the lungs and along the carotid artery of the neck. Conditions that can damage or obstruct the nerve pathway include:

  • Tumors in the upper part of the lung or chest cavity
  • Trauma to the neck or chest cavity due to surgery or accident

Third order (postganglionic) — The nerve path travels from the neck to the middle ear and eye. Problems may result from:

  • Lesions of the carotid artery
  • Middle ear infections
  • Injury to the base of the skull
  • Migraine or cluster headaches

What are the symptoms and causes of Horner’s syndrome?

The symptoms most commonly associated with Horner’s syndrome are

  • Drooping of the upper eyelid
  • Pupil of one eye appears smaller than the other
  • Decrease in sweating or lack of sweating on the face

Horner’s syndrome may be congenital or acquired.

  • Congenital: Horner’s syndrome is present at birth in a small percentage of the population. Usually, it occurs because of some type of birth trauma or injury to the nerves or carotid artery during delivery. It may be caused by a tumor (neuroblastoma). In rare cases, the syndrome may be inherited, although no specific genes have been linked to it yet. If the syndrome is present before the child is 2 years of age, the iris of the eye may be lighter on the affected side.
  • Acquired: there are many different underlying conditions that may result in Horner’s syndrome. Disorders affecting the neck, chest, and lungs, or disruption of the blood supply to the brain may result in symptoms.

Some of the many conditions that may produce Horner’s syndrome include:

  • Trauma to the neck or head
  • Infections
  • Tumor at the top of the lung
  • Lung cancer
  • Thyroid tumor
  • Migraines or cluster headaches
  • Cerebrovascular — interruption of the blood flow to the brain caused by a stroke, aneurysm, or blood clot (embolism)
  • Cancerous (malignant) or noncancerous (benign) lesion or tumor on the cervical nerves on one side of the body (very rare)
  • Surgery

How is Horner’s syndrome diagnosed?

The diagnosis of Horner’s syndrome may be complex, since other disorders may cause similar symptoms. Once a definite diagnosis is made, further tests may be required to determine the underlying cause of the symptoms.

  • Physical examination: Your doctor will conduct an examination and note any visible signs. He or she will ask if you are experiencing other symptoms, such as pain.
  • Medical history: Your doctor will ask you about your past illnesses, injuries, and surgeries.
  • Eye examination: An ophthalmologist (eye specialist) but, more often, a neuro-ophthalmologist – an ophthalmologist who specializes in neurological conditions – can perform tests to measure the response of the pupils of the eye to certain medications. The doctor will insert eye drops containing a small amount of the drug to dilate the pupils. Failure of one pupil to dilate (open) may indicate that Horner’s syndrome is present. Further tests with other types of drugs can confirm the diagnosis.
  • Imaging tests: If symptoms indicate the presence of a tumor, lesion or structural abnormality, tests may be ordered to locate the growth and determine if it is cancerous or benign. Tests may include chest X-rays, magnetic resonance imaging (MRI), computed tomography (CT scan) or ultrasound.

How is Horner’s syndrome treated?

The treatment will depend on which kind of underlying disorder is causing Horner’s syndrome. Since there are many possible causes, the kinds of treatment can vary widely. Sometimes no treatment is necessary unless the patient is experiencing pain or other discomforts. If a tumor or other abnormality is found, options may include surgery. If the tumor is malignant, post-surgical treatment may include chemotherapy and radiation.

Genetic counseling may be helpful in situations where there is a family history of Horner’s syndrome.

What is the prognosis (outlook) with Horner’s syndrome?

The prognosis of Horner’s syndrome also depends on the underlying cause. The characteristic symptoms of Horner’s syndrome generally do not have a significant impact on the quality of life or vision. However, they may indicate the presence of a serious or even life-threatening illness that requires prompt medical attention.

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