What is Susac syndrome?
Susac syndrome is a rare, autoimmune disease. Autoimmune means that your immune system mistakenly attacks your own tissues. In Susac syndrome, your immune system attacks the smallest blood vessels in your brain, retina (part of the eye), and inner ear. The blood vessels become blocked. Blocked or decreased blood flow through your blood vessels can cause problems in your brain, retina and inner ear.
Other names for the syndrome are: SICRET – small infarctions of the cochlear, retinal and encephalic tissue, and RED-M – microangiopathy with retinopathy, encephalopathy and deafness.
Who is affected by Susac syndrome?
Susac syndrome is rare, but when it occurs it strikes three times as many women as men. It mostly affects people between the ages of 20 and 40, but people outside this age group may rarely be affected.
Is Susac syndrome an inherited condition?
No, there is no evidence that Susac syndrome is inherited (runs in families).
Symptoms and Causes
What are the symptoms of Susac syndrome?
Symptoms vary from person to person. Symptoms typically correspond to the area of the body affected.
Brain symptoms (these are the most common first symptoms):
- Severe headache, often with vomiting.
- Problems with thinking, such as short-term memory loss, slow thought processing and reduced ability to solve problems.
- Slurred speech.
- Walking difficulties.
- Changes in personality.
- Psychological problems such as depression, psychosis, aggression, anxiety or withdrawal.
- Dark area in part(s) of the visual field.
- Visual disturbance (described as “a dark shade or curtain drawn over part of my vision”).
- Loss of peripheral (side) vision.
Inner ear symptoms:
- Hearing loss.
- Dizziness (vertigo).
- Ringing in the ears (tinnitus).
Most people with Susac syndrome do not have symptoms from the brain, eyes, and inner ear at the same time. Presenting symptoms can be from any of the three affected areas, but brain symptoms are the most common first symptom. About 85% of affected individuals experience symptoms from all three areas at some point during their disease course. It may take weeks, months or even years for all body areas to be affected.
What causes Susac syndrome?
Susac syndrome is the result of your own immune system attacking endothelial cells – the cells that line the inner walls of your blood vessels – in your brain, retina and inner ear. When attacked, the endothelial cells swell and can partially or completely shut off blood flow through the vessel. The blockage prevents needed nutrients and oxygen from reaching these areas.
It’s not known what causes your immune system to attack the endothelial cells.
Diagnosis and Tests
How is Susac syndrome diagnosed?
Results of a neurological exam may find that you have:
- Poor memory, confusion and poor thinking ability.
- Loss of balance.
- Difficulty walking.
- Slight paralysis or weakness.
- Overactive deep tendon reflexes.
- Poor muscle control.
Magnetic resonance imaging (MRI) may show:
- Abnormalities (lesions) in the central portion of the corpus callosum (the bundle of nerves that connects the right and left halves of the brain).
- Lesions in other areas of the brain.
- Increased visibility of the leptomeninges, the tissue that covers the brain.
Fluorescein angiography (a test that looks at blood flow in the eye) may reveal:
- Blockage of blood vessels in the retina.
- Blood vessel “leakage.”
- Increased “staining” of the walls of the vessels.
A hearing test may find:
- Various degrees of hearing loss, particularly of low-pitched sounds.
- Difficulty understanding speech.
Because its symptoms are similar to those of a number of other diseases – such as multiple sclerosis, stroke, encephalitis, lupus, Lyme disease, CNS vasculitis and many others – Susac syndrome may be difficult to diagnose.
Management and Treatment
How is Susac syndrome treated?
Susac syndrome is best treated as soon as possible with an aggressive, long-term course of drugs that suppress the immune system. Medications may include:
- Prednisone or other corticosteroids.
- Intravenous methylprednisolone.
- Intravenous immunoglobulin (IVIG).
- Mycophenolate mofetil.
- Biological therapies, such as rituximab (Rituxan®), etanercept (Enbrel®), infliximab (Remicade®).
Women should avoid oral contraceptives and estrogen-replacement therapies because certain hormones may increase the risk of blood vessel blockage.
What can be expected after treatment for Susac syndrome?
Treatment with immunosuppressive drugs slows the immune system attacks. Over time, the immune attack may become less prominent, allowing the dosage of drugs to be decreased. You will need to be monitored so that the potency of your medication regimen corresponds to the severity of the immune attack. If treatment is tapered or discontinued too quickly, the disease may flare up again.
Can Susac syndrome be prevented?
There is no way to prevent Susac syndrome because researchers don’t know what triggers the disease.
Outlook / Prognosis
What is the prognosis (outlook) for someone with Susac syndrome?
Your experience with Susac syndrome is unique to you. Some people have symptoms only once in their life. Others have symptoms that appear and disappear several times and then completely go away. In most people, symptoms come and go over two to four years on average. A small percentage of people (under 5%) have long-term, continuous flare-ups and remissions of their symptoms.
Most people recover from Susac syndrome with no or few long-term symptoms. However, some people continue to have problems with brain function (see symptoms section), and may have some degree of hearing and vision loss. A cochlear implant may help some people with severe hearing loss.