What is Susac's syndrome?

Susac's syndrome is an autoimmune disease first described in 1979 by Dr. John Susac. The term "autoimmune" means that the person's immune system mistakenly attacks the person's own tissues. In Susac's syndrome, the immune system attacks the smallest blood vessels in the brain, retina, and inner ear---causing these vessels to become blocked. This blockage causes these organs to suffer, due to decreased blood flow.

What are the symptoms of Susac's syndrome?

Brain symptoms:

  • Severe headache, often with vomiting
  • Problems with thinking, such as short-term memory loss, confusion, slow thought processing, and reduced ability to solve problems
  • Inability to remain alert or focused
  • Slurred speech
  • Changes in personality
  • Psychiatric problems such as depression, psychosis, aggression, anxiety, or withdrawal

Eye symptoms:

  • Dark area in one part of the visual field
  • Visual disturbance ("like a dark shade or curtain is drawn over part of my vision.")
  • Loss of peripheral (side) vision

Inner ear symptoms:

  • Hearing loss
  • Dizziness (vertigo)
  • Ringing in the ears (tinnitus)

It is not necessary for all three components of the disease to appear at the same time. Any one of the above symptoms may be the first sign of Susac's syndrome. It may take weeks, months, or even years for all three parts to show up. Some patients never have more than two of the components.

Who is affected by Susac's syndrome?

Susac's syndrome is a rare disease that strikes mainly females between the ages of 20 and 40. However, children as young as eight and adults (both men and women) into their 50s can be affected.

What causes Susac's syndrome?

Susac's syndrome is caused by a person's own immune system attacking the endothelial cells, (the cells that line the inner walls of our blood vessels) of vessels in the brain, retina, and inner ear. When attacked, the endothelial cells swell up and partly or completely shut off blood flow through the vessel. The resulting lack of oxygen and nutrients causes the affected organs to suffer.

What causes the immune system to malfunction in this way is not known.

How is Susac's syndrome diagnosed?

A neurological exam may find that the patient has:

  • Poor memory, confusion, and poor thinking ability
  • Loss of balance
  • Difficulty walking
  • Slight paralysis or weakness
  • Hyperactive tendon reflexes
  • Poor muscle control

Magnetic resonance imaging (MRI) may find:

  • Abnormalities (lesions) in the central portion of the corpus callosum (the bundle of nerves that connects the right and left halves of the brain)
  • Other white matter lesions
  • Lesions in the deep gray matter
  • Enhancement of the leptomeninges, the tissue that covers the brain

Fluorescein angiography looks at blood flow in the eye. Findings in Susac's syndrome include:

  • Visible white spots in the retina. These "cotton wool spots" are the result of injury due to disturbed blood flow
  • Blockage of blood vessels in the retina, known as branch retinal artery occlusion (BRAO) 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, ADEM, encephalitis, meningitis, lupus, and CNS vasculitis---Susac's syndrome may be misdiagnosed.

How is Susac's syndrome treated?

Susac's syndrome is best treated as soon as possible with an aggressive, long-term course of drugs that suppress the immune system, such as steroids. Some medications include:

  • Prednisone
  • Intravenous methylprednisolone
  • Intravenous immunoglobulin (IVIG)
  • Cyclophosphamide
  • Mycophenolate mofetil
  • Azathioprine
  • Biological therapies

Some doctors recommend that Susac's syndrome patients avoid the use of oral contraceptives and estrogen-replacement therapies because hormones may aggravate the blockage of blood vessels.

What is the prognosis (outlook) for someone with Susac's syndrome?

There are many different paths that Susac's syndrome may follow. In some people, the syndrome disappears in a few months, even without treatment. In others, symptoms keep coming back even after long-term treatment.

Susac's syndrome usually lasts between six months and five years; most patients seem to get better after about two to four years. If the symptoms during this period are mild or easily controlled with medications, there may be little or no lasting damage. Some people, however, have severe cases in which there is permanent harm, including dementia, loss of vision, and deafness. Susac's syndrome can also reappear after many years of remission.

What can be expected after treatment for Susac's syndrome?

The immunosuppressive drugs give the body a chance to correct itself while slowing down the immune system's attacks. As this correction takes place, the dosage of drugs can be decreased. It is important for the patient to be monitored by a doctor so that drug levels are kept in balance with the rate at which the immune system stabilizes. If treatment is discontinued too quickly, a flare-up of the disease may occur.

Can Susac's syndrome be prevented?

There is no way to prevent Susac's syndrome because the autoimmune response that causes it has not been identified.


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  • Genetic and Rare Diseases Information Center (GARD). Susac syndrome
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 8/15/2012...#15073