University of Calgary

FAQs

Question #1:  Initially, my physician thought I had multiple sclerosis (MS).  Now my physician thinks I have Susac's Syndrome, instead.  I understand that other patients with Susac's Syndrome were first diagnosed as MS.  Why is that?

Answer:   Multiple sclerosis (MS), which is quite common, and Susac's Syndrome, which is quite rare, both present with neurological and eye symptoms, both happen to primarily affect the same population group (young women in their 20s and 30s), both have multiple white matter lesions on MRI of the brain, and in both diseases the white matter lesions (which have the appearance of small white spots on MRI) involve the corpus callosum.  hat is the difference between the two?

However, there are several differences between Multiple sclerosis and Susac Syndrome:

  • In SS the eye disease is due to injury to the tiny blood vessels in the retina. This injury leads to the branch retinal artery occlusion (BRAO) and blood vessel "leakage" that are so characteristic of SS. Patients with MS do not develop BRAO or blood vessel "leakage." This is because MS is not a disease of blood vessels---it is a demyelinating disease. (Instead, patients with MS develop a different type of eye problem---optic neuritis.)
  • Hearing loss is expected in SS. Hearing loss is not an expected feature of MS.
  • There are distinct differences between the MRI appearance of MS and that of SS:

-The corpus callosal lesions in SS are in the central portion of the corpus callosum, whereas in MS the callosal lesions are on the under-surface of the corpus callosum.

- Whereas lesions in the deep gray matter are common in SS, the gray matter is not expected to be involved in MS

-Leptomeningeal enhancement, which is seen in approximately 33% of patients with SS, is not seen in MS.

 

Question #2:  Until I was told that I had Susac's Syndrome, I had never heard of it, nor had any of my family or friends.  How common is Susac's Syndrome? 

Answer:  Since Susac's Syndrome was first described in 1979, the world's medical literature has documented the existence of about 209 people with Susac's Syndrome.  These represent only the published cases.  We are aware of about 50 cases that have not been published.

We suspect that Susac's Syndrome is more common than these numbers would suggest.  Since 1979 the numbers of patients reported during each subsequent decade has steadily risen, primarily due to increased physician and patient awareness of the existence of the disease.  More than half of the 124 articles that have been written on Susac's Syndrome have been published since January, 2004.  As physician and public awareness increases, it is likely that Susac's Syndrome will be recognized more frequently and it will seem less rare than it is currently thought to be.

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