Horner Syndrome

What is Horner Syndrome?

Horner syndrome is a rare condition that typically results in a partially droopy upper eyelid, a small pupil, and a loss of sweating on the face. This happens due to a disruption in the sympathetic nerve supply, which helps to control these functions. The condition is usually caused by damage to this nerve supply, but there have been a few instances where people have been born with it. Treatment focuses on locating and responsibly managing whatever might be causing the damage.

This syndrome is known by several other names in various English and French-speaking countries, such as Bernard-Horner syndrome and oculosympathetic palsy. One specific version, called Von Passow syndrome, includes a change in eye color.

The condition was first recorded by Francois Pourfour du Petit in 1727 after he observed changes in animals’ eyes and faces after certain nerves had been cut. Later, many doctors offered different interpretations of the syndrome. It was then officially described and named after Johann Friedrich Horner, a Swiss eye doctor, in 1869.

To fully understand this syndrome, it helps to understand the nerve supply to the eye. The nerves that control the eye consist of three different sets of neurons that start from a part of the brain called the hypothalamus and end in the eyelid muscles and iris, the colored part of the eye.

These nerve pathways are important for control of facial sweating, dilation of the pupil, and the ability to lift the upper eyelid properly. Any disruption along this nerve supply can lead to the symptoms seen in Horner syndrome.

What Causes Horner Syndrome?

Horner syndrome is typically a condition that is gained later in life due to diseases affecting the body as a whole or a specific region, or it can be an unintended consequence of a medical procedure. However, Horner syndrome can also be present from birth and passed down through families in rare instances. It has to do with damage to the ‘sympathetic fibers,’ which are a type of nerve that can be found pretty much all over the body and can be damaged in various ways.

The sympathetic fibers can either be interrupted centrally, which is between the hypothalamus (a part of your brain) and a point in the spinal cord, or they can be interrupted peripherally, which is along the path of a large artery in the neck. Horner syndrome is particularly concerning when it is pre-ganglionic, meaning it happens before the nerves reach the spinal cord, as it may be linked to cancers of the lung.

The causes of Horner syndrome can be grouped based on where in the body the nerve damage occurred.

Firstly, ‘first-order neurons,’ which are the first in the chain of communication from the brain, are often affected by conditions within the brain. These include stroke, multiple sclerosis, a condition where the lower part of the brain pushes down onto the spinal cord (Arnold-Chiari malformation), various types of inflammation of the brain and spinal cord, certain tumors within the brain, spine injuries that occur above a certain level, and spinal cord tumors.

Second, ‘second-order neurons,’ which deliver messages from the brain to the chest area, can be affected by lung cancers (specifically Pancoast tumor), a rib that is higher up than normal, abnormal bulging in the artery under the collar bone, enlarged lymph nodes in the space between the lungs, injuries to the network of nerves in the shoulder (brachial plexus), a type of tumor along the spine, a deep gum infection, or surgeries that can cause it unintentionally such as thyroidectomy, neck dissection, tonsil removal, heart bypass surgery, or certain imaging tests for the arteries.

Finally, ‘third-order neurons,’ which are located near a major artery in the neck and a part of the brain called the cavernous sinus, can be disrupted by an abnormal connection between arteries and veins in the brain, a tear or bulge in the same major artery, recurrent severe headaches, a syndrome causing one-sided facial pain and headache along with Horner syndrome, shingles infection, or inflammation of the arteries in the head.

Risk Factors and Frequency for Horner Syndrome

Horner syndrome is a rare condition, happening about once in every 6,000 people. This syndrome can affect anyone, regardless of their age or ethnic background.

Signs and Symptoms of Horner Syndrome

When dealing with Horner syndrome, it’s crucial to identify where the problem is located in order to choose appropriate treatment steps. A thorough history and physical examination are key. Certain symptoms and past experiences can provide helpful clues:

Problems with balance, hearing, sensation, or swallowing might suggest involvement of the first-order neurons, suggesting a more central issue.
If there’s a past history of injury or surgery affecting the head, face, neck, shoulder, or back, this could point to a problem with the second-order neurons.
It’s important to know the patient’s full medical and drug history in order to rule out the use of medicines that might affect the pupils.
Symptoms like a headache, double vision, facial numbness, or pain could signal involvement of the third-order neurons.
Anhidrosis (a lack of sweating) can provide another clue, depending on where it occurs.
Details about any headaches the patient experiences may also be useful.

Symptoms that have been around a long time may point towards a more benign cause compared to rapidly worsening symptoms such as weight loss, coughing blood, low-grade fever, and swollen lymph nodes. Reddening of the face may suggest a disorder involving the preganglionic neurons. If the patient has facial or orbital pain along with small pupils and drooping eyelids, this could be a sign of Raeder paratrigeminal syndrome. A past history of skin lesions or herpes zoster infection should also be noted, along with the severity and location of any pain.

A comprehensive eye examination is also necessary, which should include:

Checking pupil responses to light and alterations in viewing distance
Measuring the size of the pupils in dim and bright light
Examining the upper eyelid for signs of drooping and tiredness
Assessing eye movements
Checking vision, including color vision and visual fields
Performing a slit-lamp examination to observe the structural details of the eye
Checking for the presence of nystagmus, a condition that causes rapid, involuntary eye movement

An examination might reveal a small, round pupil in the affected eye, which dilates more slowly than it should. This is typically more noticeable in the dark. The eye’s response to a regional pain stimulus (the ciliospinal reflex) might also be missing. Other signs could include partial eyelid drooping, changes in iris color, an apparent sinking of the eye into the orbit (enophthalmos), eyelid retraction on the other side, reddened conjunctiva, and no change or a temporary decrease in the pressure inside the eye.

Finally, it’s important to carry out a thorough check of the whole body, with particular attention to the nervous, respiratory, and cardiovascular systems. This can help to identify or exclude other potential causes of the patient’s symptoms.

Testing for Horner Syndrome

If your doctor believes something might be wrong, they might suggest a few different tests. They could ask for a complete blood count, a test to measure how fast your red blood cells settle at the bottom of a test tube (erythrocyte sedimentation rate or ESR), or a serum chemistry panel, which measures different chemicals in your blood.

If they think you might have an infection, they might ask for a urine or blood culture. Other tests could be recommended depending on your symptoms and what your doctor finds in the initial examination, such as tests for neurosyphilis, HIV, thyroid function, and levels of vitamin B-12 and folate. In children, if they suspect a type of cancer called neuroblastoma, they might ask for urine testing to check for certain chemical byproducts. If tuberculosis is suspected, a skin test known as purified protein derivative (PPD) might be necessary.

Imaging could also be ordered, like a chest X-ray or a computed tomography (CT) scan if lung cancer is suspected. If a stroke is possible, a head CT or magnetic resonance imaging (MRI) might be ordered. MRI is preferred over ultrasound if there’s a chance of a problem with the carotid artery, such as a tear in the artery wall (carotid artery dissection).

There are also some special tests that can be used to diagnose certain conditions. One of these is the topical cocaine test. This involves putting a cocaine solution in both eyes and observing the reaction. The eye that doesn’t dilate as much might be the affected one. However, this test isn’t perfect. It’s expensive, time-consuming, can give unclear results, and cocaine can show up in urine tests.

Another option is the topical hydroxyamphetamine test, where a solution is placed in both eyes. The eye that doesn’t dilate as well may be the one affected. This test can’t be done on the same day as the cocaine test and can sometimes give false-negative results.

The last option is the topical apraclonidine test. This solution is put in both eyes and usually results in the affected eye dilating more. However, this test can give false negatives in the early stages of a problem, cause side effects in children, can’t identify where the issue is, and the drug has a relatively long-lasting effect.

Other options have been proposed but aren’t commonly used due to various limitations, such as poor penetration through the cornea, varying results, or limited availability.

Treatment Options for Horner Syndrome

The treatment options for this condition majorly depend on correctly identifying what is causing it. This is why it’s very important to get a diagnosis as soon as possible. Once you have a diagnosis, you’ll likely be referred to a specialist who can provide the right treatment for your situation. Doctors also suggest having regular eye check-ups, as they can help in identifying such conditions early.

If the cause of the disease requires surgery, the type of surgical intervention will depend on that cause. The following are some surgical treatment options:

* If your condition is linked to an aneurysm, you might need to have a procedure done by a neurosurgeon, who is a doctor specializing in problems related to the brain, spine, and nerves.
* If diseases like carotid artery dissection or aneurysm (which are conditions related to the heart and blood vessels) are causing your problem, you might need to see a vascular surgeon, who is a doctor that treats diseases of the vascular system.

As mentioned before, if a person has pain alongside Horner syndrome, it might be a sign of a more serious hidden condition that needs detailed examination. Symptoms like weight loss and feeling tired all the time might hint towards a possible hidden disease like cancer. Also, Horner syndrome could be one of the first signs of a disease called neuroblastoma in children.

When the large blood vessel in the neck, known as the carotid artery, suffers a dissection, it can cause a one-sided headache and facial or neck pain. This needs to be quickly checked and treated if it’s suspected.

Raeder paratrigeminal syndrome is another condition that can cause headaches, but it’s also accompanied by impairment of the trigeminal nerve, known clinically as CN V.

On the other hand, unequal pupil size (Anisocoria) and/or droopy eyelids (ptosis) can be caused by numerous diseases and conditions. These might include:

Holmes-Adie syndrome
Neurosyphilis (known for causing a unique pupil condition called the Argyll Robertson pupil)
Third nerve palsy
Optic neuritis – inflammation of the optic nerve.

What to expect with Horner Syndrome

The long-term outlook for people with Horner syndrome, which seems to occur without any known cause, is generally good. In most cases, patients’ conditions do not get worse. In fact, about half no longer show uneven pupil sizes or ‘anisocoria,’ which is one of the main signs of Horner syndrome.

Almost one-third of people with a drooping eyelid or ‘ptosis,’ another feature of Horner syndrome, see their symptoms either improve on their own or completely go away. This usually occurs about 7.9 years after they have been diagnosed with Horner syndrome. In situations where only one eye is affected, the problem does not typically spread to the other eye.

It’s worth noting that new medical conditions can develop anywhere between 3 and 20 years after a Horner syndrome diagnosis. However, these are generally not directly related to Horner syndrome.

Possible Complications When Diagnosed with Horner Syndrome

Horner syndrome usually happens because of another health problem like a tumor, an injury, or an infection. It’s very rarely a condition that happens on its own. The complications that come from having Horner syndrome are mostly because of the root cause of the syndrome.

For example, those with Horner syndrome due to multiple sclerosis could experience muscle stiffness or spasms, and might have trouble with their bladder, bowel, or sexual function. They might even develop seizures. On the other hand, problems related to the eyes because of Horner syndrome could affect a person’s sight. In some cases, this might just be temporary but in others, it could lead to partial or even total blindness.

The complications typically include:

Muscle stiffness or spasms (for multiple sclerosis patients)
Impaired bladder, bowel, or sexual function (for multiple sclerosis patients)
Seizures
Temporary or permanent vision impairment
Partial or complete blindness

Preventing Horner Syndrome

Patients should be given information about the different ways Horner syndrome can appear. If your baby is born with this condition, known as congenital Horner syndrome, it’s crucial to understand the various treatment options and the need for regular medical checks. Horner syndrome won’t harm the eye or lead to vision loss; however, it could indicate damage along the nerve.

Understanding where and why the nerve damage occurred is vital, as sometimes the reason could be serious. For instance, a droopy lid (or ‘ptosis’) can cause the eyes to dry out or turn red due to being exposed for too long. You might also feel a rough sensation in the eye and be more susceptible to eye infections.

Often, using artificial tears or ointment can help manage these symptoms. Yet, in more severe cases or when complications arise, surgical intervention might be necessary.

Frequently asked questions

Horner Syndrome is a rare condition that results in a partially droopy upper eyelid, a small pupil, and a loss of sweating on the face. It is caused by a disruption in the sympathetic nerve supply that controls these functions.

Horner syndrome is a rare condition, happening about once in every 6,000 people.

Signs and symptoms of Horner Syndrome include: - Problems with balance, hearing, sensation, or swallowing, which may suggest involvement of the first-order neurons, indicating a more central issue. - Past history of injury or surgery affecting the head, face, neck, shoulder, or back, pointing to a problem with the second-order neurons. - Full medical and drug history is important to rule out the use of medicines that might affect the pupils. - Symptoms like headache, double vision, facial numbness, or pain, which could signal involvement of the third-order neurons. - Anhidrosis (lack of sweating) can provide a clue, depending on its location. - Details about any headaches the patient experiences may also be useful. - Symptoms that have been present for a long time may suggest a more benign cause compared to rapidly worsening symptoms such as weight loss, coughing blood, low-grade fever, and swollen lymph nodes. - Reddening of the face may suggest a disorder involving the preganglionic neurons. - Facial or orbital pain along with small pupils and drooping eyelids could be a sign of Raeder paratrigeminal syndrome. - Past history of skin lesions or herpes zoster infection should be noted, along with the severity and location of any pain. In addition to these signs and symptoms, a comprehensive eye examination is necessary, which includes checking pupil responses to light, measuring pupil size in different lighting conditions, examining the upper eyelid for drooping, assessing eye movements, checking vision and color vision, performing a slit-lamp examination, and checking for the presence of nystagmus (involuntary eye movement). During the examination, a small, round pupil in the affected eye that dilates more slowly than it should, especially in the dark, may be observed. The ciliospinal reflex, which is the eye's response to a regional pain stimulus, might be missing. Other signs can include partial eyelid drooping, changes in iris color, enophthalmos (apparent sinking of the eye into the orbit), eyelid retraction on the other side, reddened conjunctiva, and no change or temporary decrease in eye pressure. A thorough check of the whole body, with particular attention to the nervous, respiratory, and cardiovascular systems, is also important to identify or exclude other potential causes of the patient's symptoms.

Horner syndrome can be gained later in life due to diseases affecting the body or a specific region, it can be an unintended consequence of a medical procedure, or it can be present from birth and passed down through families in rare instances.

The other conditions that a doctor needs to rule out when diagnosing Horner Syndrome are: - Holmes-Adie syndrome - Neurosyphilis (known for causing a unique pupil condition called the Argyll Robertson pupil) - Third nerve palsy - Optic neuritis - inflammation of the optic nerve.

The types of tests that may be needed to diagnose Horner Syndrome include: - Topical cocaine test: This involves putting a cocaine solution in both eyes and observing the reaction. The affected eye may not dilate as much. - Topical hydroxyamphetamine test: A solution is placed in both eyes, and the eye that doesn't dilate as well may be the affected one. - Topical apraclonidine test: This solution is put in both eyes, and the affected eye usually dilates more. Other tests may also be ordered depending on the symptoms and initial examination findings, such as imaging tests like a chest X-ray or CT scan, and referral to a specialist for further evaluation and treatment.

The treatment options for Horner Syndrome depend on correctly identifying the cause of the condition. Once a diagnosis is made, the patient will likely be referred to a specialist who can provide the appropriate treatment. Regular eye check-ups are also recommended to identify the condition early. If the cause of Horner Syndrome requires surgery, the type of surgical intervention will depend on the specific cause. For example, if the condition is linked to an aneurysm, a neurosurgeon specializing in brain, spine, and nerve problems may perform a procedure. If the problem is related to the heart and blood vessels, a vascular surgeon may be needed.

The side effects when treating Horner Syndrome can vary depending on the underlying cause of the syndrome. Some potential side effects and complications include: - Muscle stiffness or spasms (for multiple sclerosis patients) - Impaired bladder, bowel, or sexual function (for multiple sclerosis patients) - Seizures - Temporary or permanent vision impairment - Partial or complete blindness

The long-term outlook for people with Horner syndrome is generally good. In most cases, patients' conditions do not get worse. About half of the patients no longer show uneven pupil sizes or 'anisocoria,' and almost one-third of people with a drooping eyelid or 'ptosis' see their symptoms either improve on their own or completely go away. However, new medical conditions can develop anywhere between 3 and 20 years after a Horner syndrome diagnosis, but these are generally not directly related to Horner syndrome.

You should see a specialist such as a neurosurgeon or a vascular surgeon for Horner Syndrome.

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