What Is Susac Syndrome?

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Susac syndrome (SuS) is a rare autoimmune disease where the body’s immune system mistakenly attacks the lining of the smallest blood vessels in the brain, retina, and inner ear. This attack causes blood vessels to be injured and swollen, blocking blood flow, oxygen, and nutrients to the brain, retina, and inner ear. SuS is also known as retinocochleocerebral vasculopathy.

The prevalence of SuS is unknown, but the condition primarily affects young women between the ages of 20–40. Women generally are affected three times more often than men by SuS. But children and adults—both male and female—regardless of age, can be affected.

SuS is considered a rare disorder, but the actual numbers of people affected are unknown. And because it is often unrecognized and can be misdiagnosed, it can be challenging to determine a true prevalence.

Here is what you need to know about Susac syndrome, including symptoms, causes, diagnosis, treatment, and prognosis.

patient's test results
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Susac Syndrome Symptoms

SuS causes three main symptoms—encephalopathy (impaired brain function), vision loss, and hearing loss. These symptoms result from decreased and blocked blood flow.

Brain symptoms may include:

  • Headaches, often accompanied by vomiting
  • Problems with thinking, short-term memory loss, confusion, and problem-solving
  • Issues with focus and alertness
  • Slurred speech
  • Personality changes
  • Mood problems, including depression, anxiety, anger, and aggression
  • Psychosis, including delusions and hallucinations

Eye symptoms can include:

Inner ear symptoms may include:

A person with SuS may not experience all three parts of the disease at once. Any of the above symptoms can be a first sign of the condition. And it may take weeks, months, or years for all three parts of the disease to appear. Some people may never experience all three phases of SuS.

A study reported in 2016 by the journal Medicine studied 10 patients, ages 35–45, diagnosed with SuS to determine signs at onset and during the disease’s course, findings on imaging studies, and treatment outcomes.

Only two of the study participants were experiencing all three sets of symptoms—brain, retina, and inner ear—at the start of the study. During the 35-month follow-up period, seven study participants developed all three symptom sets, and the average time for full disease onset was determined to be seven months.

The researchers concluded that most people with this condition do not present with all three sets of symptoms early on, but most will go on to develop the triad of symptoms.

Causes

There are no known or specific causes of Susac syndrome. But researchers do know the condition is caused by the body’s immune system attacking the endothelial cells.

It is unknown what causes the immune system to malfunction in the way that it does. Some autoimmune diseases are inherited. But there has been no evidence to date suggesting SuS is inherited or that there are cases where more than one family member is affected by the condition.

The endothelial cells line the inner walls of the blood vessels in the brain, retina, and inner ear. When SuS attacks the tiny blood vessels, the endothelial cells become inflamed and partly or entirely shut off the blow flow to the vessel.

With the blood vessel blocked off, the lack of oxygen and nutrients will cause the affected organ (of the brain, retina, or inner ear) to suffer.

Because researchers have not identified autoimmune causes of SuS, there is no way of knowing if Susac syndrome can be prevented.

Diagnosis

A diagnosis of Susac syndrome is based on a physical exam, a detailed medical history along with symptom history, and imaging studies. Imaging for SuS may include magnetic resonance imaging (MRI).

An MRI image for someone with SuS will show changes in the brain, especially in the corpus callosum—the part of the brain connecting the left side to the right side.

This connection allows for information to pass between the two halves, called hemispheres. The findings seen at the corpus callosum—such as swelling, leakage, and lesions—are those specific to Susac syndrome.

An eye exam called fluorescein angiography may be used to make a diagnosis of SuS based on eye symptoms. This test measures blood flow through the retina. Additional testing may include a hearing exam to check for hearing loss and a cerebrospinal fluid analysis to look for high levels of inflammatory proteins specific to SuS.

Because symptoms of SuS are similar to several other diseases, including multiple sclerosis, encephalitis, and meningitis, your doctor may consider additional testing to rule out other conditions. This testing may include bloodwork and other types of imaging studies, including X-ray and computerized tomography (CT).

Treatment

Early and aggressive treatment is needed to treat Susac syndrome, regardless of whether you experience one set of symptoms, two or all three. Treatment is aimed at preventing or minimizing irreversible damage to the brain, eyes, and ears, preventing new disease signs, and improving existing symptoms.

Unfortunately, it may be impossible to repair or reverse any existing neurological, vision, or hearing damage.

Susac syndrome can be treated with immunosuppressive drugs, corticosteroids, biologics, and intravenous cyclophosphamide, and immunoglobulin drugs. These medications can stop the immune system from attacking the blood vessels in the brain, eyes, and ears. A hearing aid or cochlear implant may help to restore hearing loss.

Treatments for Susac syndrome can allow the body to slow down the immune system’s attacks. The dosage of medications can be decreased once there is symptom improvement.

Prognosis

It is hard to predict a long-term outlook for most people with Susac syndrome because the course of the disease varies from person-to-person.

Research on treatment on SuS shows most people recover fully without long-term damage or disability. Some people will only experience a few episodes of the condition before they fully recover. Others only experience a mild form of the disease for their entire lives.

Some people have a chronic, reoccurring disease course with frequent flare-ups (periods of high disease activity) and remissions (periods with few or no symptoms). There are reported cases of SuS reoccurrence decades after full recovery. 

Some people with Sus have little or no long-term disease effects. In contrast, others will continue to have problems with cognition, gait, and hearing for the remainder of their lives. Vision loss with SuS is usually not severe. There have only been a few reported incidences where people have died of complications of Susac disease.

 A Word From Verywell

Susac syndrome tends to be a self-limiting condition in that for most people, it can be treated with no severe, long-lasting harm. In rare cases, there is permanent harm, which can include dementia, vision loss, or hearing loss. Susac syndrome can also reappear after many years of remission.

But the outlook for most people who develop Susac syndrome tends to be positive. Of course, an improvement from SuS starts with a diagnosis and early treatment.

Talk to your doctor right away if notice changes with your hearing or vision, or if you think you are having problems with your gait or cognition. Getting the care you need as soon as possible can reduce symptoms, prevent complications, and improve your quality of life. 

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