Horner Syndrome

Quick Answer

Horner syndrome is caused by damage or disruption of the nerves connecting the brain, the face, and the eyes. It can have a variety of underlying causes, but in babies born with Horner syndrome, the most common cause is traumatic birth injury due to mistakes made in the delivery room.

What Is Horner Syndrome?

Horner syndrome (also called Horner-Bernard syndrome or oculosympathetic palsy) is caused by issues with the nervous system, resulting in the disruption of a nerve pathway between the brain, face and eye on a single side of the body.

There are 3 groups of nerve cells (neurons) that can affect this nerve pathway:

  • First-order neurons: This pathway passes from the upper part of the spinal cord through the brainstem to the hypothalamus at the base of the brain.
  • Second-order neurons: These neurons extend from the spinal cord, across the upper chest, and into the side of the neck.
  • Third-order neurons: These nerves create a pathway across the neck and into the skin of the face, including the muscles that control the iris and eyelid.

Horner syndrome can be caused by a wide variety of abnormalities along any of these three neuron pathways and can appear in individuals at any stage of life. Roughly 5% of cases are congenital, affecting a baby from the moment they are born.

There is no specific treatment for Horner syndrome, as the underlying cause must be identified and treated. In some cases, however, the underlying issue may not be treatable.

Causes of Horner Syndrome

The most common identifiable cause of congenital Horner syndrome is a traumatic birth injury to the neck and shoulders. These injuries are present in 53% of congenital cases and occur from a wide variety of sources.

Potential causes of Horner syndrome stemming from a birth injury include:

In some cases, congenital Horner syndrome may have less preventable causes such as tumors, cancers, and damage to major veins and arteries. Late-occurring or non-congenital cases may also have a traumatic cause, such as injuries sustained from a serious accident or complications from mistakes made during surgery.

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Symptoms of Horner Syndrome

The neurological and physical symptoms of Horner syndrome are often subtle and difficult to detect. Even in congenital cases, it may take some time for parents and doctors to notice that anything out of the ordinary is occurring.

Horner syndrome symptoms include:

  • Delayed pupillary dilation in dim light
  • Dizziness
  • Drooping upper eyelid (ptosis)
  • Elevation of the lower lid
  • Heterochromia (lighter color in the affected eye)
  • Impaired vision
  • Lack of flushing on the affected side of the face
  • Little to no sweating on the affected side of the face (anhidrosis)
  • Muscle weakness/lack of muscle control
  • Neck pain
  • Persistently small pupil (miosis)
  • Severe or sudden headache
  • Significant difference in pupil size (anisocoria)
  • Sunken eye

In the wake of a difficult birth, it is important to keep a close eye on the baby for any signs of lingering medical consequences. Parents should stay in close contact with their child’s doctor and should report any issues, no matter how small.

Studies have shown that the median age of diagnosis for congenital Horner syndrome is 4.1 months. Symptoms must be observed by parents or doctors within the first 5 months of a baby’s life to be considered congenital.

Diagnosing Horner Syndrome

Diagnosing Horner syndrome can be a lengthy process. Because there is such a wide variety of possible causes — and an equally large number of potential locations where the problems could appear — it can take time for all necessary testing to be completed.

One of the most common methods of diagnosing Horner syndrome is to test the reaction of the pupils. An ophthalmologist (eye doctor) may use drops that force the pupil to dilate or constrict. The eye on the affected side of the body will often be less reactive than the unaffected eye. This uneven response is an indicator that Horner syndrome may be a problem.

Other potential diagnostic tests include:

  • Carotid ultrasound
  • CT scan (computed tomography)
  • MRI (magnetic resonance imaging)
  • X-ray

For children born with congenital Horner syndrome, studies have shown that the most important indicator is whether they potentially suffered trauma during a difficult birth. If it can be proven that the child suffered birth trauma, then extensive systematic testing may not be needed as long as their symptoms do not worsen.

Since Horner Syndrome is caused by underlying issues, it is important to act quickly to discover the source of the problem. Symptoms may worsen if the damage goes untreated.

Can Horner Syndrome Be Prevented?

Not all cases of congenital Horner syndrome can be prevented. Some babies are born with defects of the vascular system or rare types of cancer which — while tragic — are not preventable.

However, multiple studies have shown that most cases of congenital Horner syndrome are caused by preventable birth injuries.

Some births are more difficult than others, and some babies need a little extra help entering the world. Doctors have a duty to provide a high standard of care during childbirth. Poor training, inadequate staffing, and a lack of preparation can all lead to mistakes by medical practitioners that can cause serious and permanent birth injuries.

Horner Syndrome and Medical Negligence

Mothers and babies deserve the best possible care during childbirth. If this care is not provided and mistakes are made in the delivery room, it can leave lifelong consequences for families.

If your child suffered a preventable birth injury, you may be able to pursue legal action against the medical team that was negligent with their care. Get a free case review today to see if your family is eligible for financial compensation.

Birth Injury Support Team

The Birth Injury Justice Center was founded in 2003 by a team of legal professionals to educate and empower victims and families affected by birth injuries. Our team is devoted to providing you with the best resources and legal information for all types of birth injuries.

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