Susac syndrome is a rare immune-mediated condition that affects the brain, eyes, and ears. Treatment involves taking medication to suppress the immune system.

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Your immune system helps your body fight off illness and infection and heal from injury. When this system doesn’t work as intended, it may affect healthy cells and cause health conditions.

Susac syndrome is one type of immune-mediated disorder that may impact the body in this way. Here’s what you need to know about Susac syndrome, what causes it, and what treatments may help.

Susac syndrome is a rare immune-mediated condition that was discovered by John Susac in 1979. Immune-mediated endotheliopathy is a vascular disorder that affects the small blood vessels (capillaries, venules and arterioles) in the brain, eyes, and ears. It’s considered immune-mediated because the exact triggers causing your body to produce the antibodies that attack these blood vessels are unknown.

Recent studies suggest that there are only 500 individuals with Susac syndrome worldwide, but the exact number of people with this disease is unknown.

Susac syndrome is distinguished by symptoms affecting the brain, eyes, and ears. The number of symptoms and severity of the symptoms depends on the person.

Symptoms in all three areas rarely occur together, especially at the start of the condition.

Brain-related symptoms:

Eye-related symptoms:

  • blind spots or black area in the visual field (scotoma)
  • peripheral vision loss
  • blurry vision
  • eye floaters or flashes (photopsias)

Ear-related symptoms:

Skin-related symptoms:

Not everyone with Susac syndrome may experience the same symptoms. And not all symptoms may affect a person at the same time. Symptoms tend to follow a relapsing-remitting pattern in a 1- to 3-year period up to a 3- to 10-year period, depending on the form.

Researchers don’t know exactly what causes Susac syndrome. They do know that it is caused by the immune system attacking healthy cells.

With Susac syndrome, the immune system attacks the lining of the small blood vessels in the brain, retina (eyes), and cochlea (inner ear). When these blood vessels are injured, blood flow is slowed or blocked by swelling. As a result, the affected areas don’t receive the oxygen and nutrients they need, causing symptoms or permanent damage.

The underlying reason why the immune system behaves this way is unknown.

Again, the true incidence of Susac syndrome is not fully known. It is not an inherited disorder, meaning it is not passed down in families.

Researchers have identified various risk factors associated with the condition:

Make an appointment to see your doctor if you experience one or more symptoms of Susac syndrome. Your doctor will listen to your health history and give you a physical exam. In this exam, your doctor will look to see if you have symptoms that fit the “clinical triad” — symptoms in the brain, ears, and eyes — characteristic of the condition.

Susac syndrome may be hard to diagnose because it shares symptoms with other disorders. Your doctor may send you for further evaluation by a neurologist, ophthalmologist, and otolaryngologist.

Tests may include:

Some cases of Susac syndrome get better on their own with no treatment. That said, treating symptoms early may help to ward off permanent damage to the eyes, ears, and brain.

Treatment may include taking medications to suppress the immune system, like corticosteroids and intravenous immunoglobulins (IVIG). Depending on the severity, your doctor may also suggest other medications, including:

Additional treatment may be necessary to address the effects of Susac syndrome. For example, a person may need hearing aids or cochlear implants to help with hearing loss.

The outlook for people with Susac syndrome is good if they receive timely and appropriate treatment.

Issues with the brain and retina may get better over time after treatment. However, any hearing loss is typically permanent. Likewise, when diagnosis is delayed, up to 50% of people may develop long-term cognitive issues.

Even after initial treatment, Susac syndrome may occur again. A relapse may happen years after the initial flare or during other situations, like pregnancy.

What triggers Susac syndrome?

Researchers do not know exactly what triggers Susac syndrome and other immune-mediated diseases. It may be a mix of genetic and environmental factors.

Is Susac syndrome ever misdiagnosed?

There are a few conditions that share certain features of Susac syndrome and may lead to misdiagnosis. They include:

Can you prevent Susac syndrome?

No. Susac syndrome is an immune-mediated disorder. Since doctors don’t know exactly what triggers it, it isn’t possible to prevent it.

Susac syndrome, a type of immune-mediated disorder affecting the brain, eyes, and ears, may be difficult to diagnose because the characteristic symptoms may not happen together. Symptoms may also overlap with other conditions.

Make an appointment with your doctor if you experience symptoms that concern you. Early diagnosis and treatment can help prevent permanent damage to the brain, eyes, and ears.