Susac’s syndrome

Synonyms

2

Overview

Susac's syndrome (also Known as Retinocochleocerebral Vasculopathy, and Susac syndrome) is a microangiopathy characterized by encephalopathy, branch retinal artery occlusions and hearing loss. The cause is unknown but the current thinking is that antibodies are produced against endothelial cells in tiny arteries which leads to damage and the symptoms related to the illness. Despite this being a rare disease, there are 4 registries collecting data on the illness; two are in the United States, one is in Germany and the fourth is in Portugal.

Symptoms

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.

Causes

Susac's syndrome is an autoimmune endotheliopathy, a disorder in which the body's immune system mistakenly attacks the inside lining (endothelium) of the walls of the very tiny blood vessels that supply blood to the brain, retina, and inner ear. The exact, underlying reason why this occurs is unknown. Why the microvasculature in the brain, retina, and inner ear are primarily affected is also unclear. The skin may also be involved.

Diagnosis

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.

Prognosis

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.

Treatment

Early and aggressive treatment is important to prevent irreversible neurological damage, hearing loss, or vision loss. Medications used include immunosuppressive agents and corticosteroids such a prednisone, or intravenous immunoglobulins (IVIG). Other drugs that have been used are mycophenolate mofetil (Cellcept), azathioprine (Imuran), cyclophosphamide, rituximab, and anti-TNF therapies.

Hearing aids or cochlear implants may be necessary in the event of hearing loss.