Horner's syndrome, also known as Horner syndrome, oculosympathetic palsy or Horner-Bernard syndrome, is a relatively rare syndrome that affects the nerves that run from the brain to the eye. To date, Horner syndrome remains somewhat of a mystery to medical researchers. What is known is that prior history of certain diseases or traumas may lead to the later onset of Horner syndrome.
Definition & Facts
Horner syndrome is considered to be in the family of neurological disorders that affect the brain, spinal cord, and central nervous system of the body. Horner syndrome can strike anyone of any age, gender or ethnicity and affects females and males equally. The syndrome can arise all on its own, or it can be prompted by another pre-existing condition, disease, or trauma.
In some individuals, it is present from birth and is a congenital disorder. In these rarest of cases, it is termed "congenital Horner syndrome." If the syndrome presents before the individual has reached two years of age, the iris portion of each eye may be different colors. Horner syndrome is sufficiently rare that no statistics exist on incidence in the population today.
Symptoms & Complaints
- Drooping eyelid (ptosis) on the side of the face that is affected.
- Lack of sweating (anhidrosis) on the side of the face that is affected.
- Decreased size in the pupil (miosis) of the eye that is affected.
These three symptoms, when occurring together, can accurately point to Horner syndrome. Sometimes the eyeball on the affected side will also sink further into the socket (orbit). In young children who have Horner syndrome, there may also be a noticeable paleness on the affected side of the face.
The causes for Horner syndrome can vary greatly. In some cases, Horner syndrome can occur on its own in an individual of any age. In other rarer cases, Horner syndrome is present at birth though the exact genetic mutations at play have not yet been identified. Inheritance appears to be autosomal dominant.
The underlying cause of Horner syndrome is nerve damage. The damage occurs in the nerves leading from the brain to one eye. There are three main groups of cells that exist along the nerve pathway that is affected by Horner syndrome. Sometimes physicians can extrapolate the cause of Horner syndrome by matching the triggering disease to the group of neurons that disease affects.
There are many pre-existing conditions or injuries that may either be risk factors for Horner syndrome or cause damage to one of the three neuron groups that can trigger the onset of Horner syndrome. Lesions of the first order (central) neurons may be caused by or linked to:
- Spinal cyst (Syringomyelia).
- Trauma to the neck such as a cervical fracture
- Trauma to or loss of the myelin sheath which protects the nerves.
Lesions of the second-order neurons may be caused by or linked to:
- Lung cancer specifically a type of lung cancer that grows at the top of the lungs called a Pancoast tumor.
- Myelin sheath tumor.
- Cardiac surgery.
Lesions of the third-order neurons may be caused by or linked to:
- Damage to the carotid artery.
- Damage to the internal jugular vein.
- Migraine headaches.
- Cluster headaches.
- Tumor or infection near base of the skull.
It is important to remember that, in some cases, it is not possible to determine the cause of Horner syndrome. These cases are called idiopathic. These cases are also different from congenital Horner syndrome.
Diagnosis & Tests
Diagnosing Horner syndrome begins with taking a thorough medical history of the patient and his or her family. The physician will look for any family history of Horner syndrome and also look for prior personal history of any of the diseases or injuries that have been linked to the onset of Horner syndrome. From here, the physician will catalog the chief symptoms before requesting and performing tests. Tests that are commonly done include the following:
- Eye drop test. By putting drops in each eye, an ophthalmologist can determine whether eye function is different in the eye suspected to be affected by Horner syndrome.
- X-ray. To look for abnormalities in the chest area, including trauma, complications from past surgery, and tumors.
- MRI (magnetic resonance imaging). To look for tumors or trauma in the brain, neck and spinal cord.
- CT (computed tomography) scan. Also to look for tumors or trauma in the brain, neck and spinal cord.
- Blood tests and clinical urine tests. These are often ordered in children presenting with symptoms of Horner syndrome. The blood and urine tests look for evidence of a neuroblastoma, a type of neuroendocrine tumor that usually occurs in the adrenal gland and affects the nervous system.
- Additional tests may include kidney function tests, liver function tests, and tests that analyze electrolyte levels, thyroid function, and levels of iron.
Treatment & Therapy
At this time, there is no one uniform treatment or cure for Horner syndrome. Treatment focuses on resolving the condition(s) thought to be causing the symptoms of Horner syndrome. Surgery may be required for any aneurysms associated with Horner syndrome. If lung cancer is the culprit, treatment may incorporate chemotherapy and/or radiotherapy.
Sometimes, cosmetic surgery is recommended to correct the drooping eyelid on the side of the face affected by Horner syndrome. In some cases, no additional treatment is necessary. So long as the underlying condition can be successfully resolved, Horner syndrome will often resolve on its own.
Prevention & Prophylaxis
These preventative measures can help avoid the onset of Horner syndrome, but they are not a guarantee. Where there is no known cause for the onset of Horner syndrome, there is no prevention.