What is Susac Syndrome?
Susac Syndrome is an extremely rare disorder which is characterized by abnormalities in the three most major organs of the body which is the brain, the eyes, and the ears. In Susac Syndrome, the affected individual will experience encephalopathy with impaired functioning of the brain, branch retinal artery occlusion damaging the retina leading to visual impairment, and inner ear disease damaging the cochlea leading to progressive hearing loss.
There are basically three forms of Susac Syndrome depending on which part of the body is more affected. In the first part, the brain is the most affected resulting in severe encephalopathy. In the second part, the eyes are the most affected with severe damage to the retina due to branch renal artery occlusion and in the third part the disease starts off with encephalopathy but as the disease progresses, the eye and the ear problem take center stage and the encephalopathy more or less resolves. The first form of Susac Syndrome which is the encephalopathic form usually resolves spontaneously with time which may range from one to four years whereas the second and the third forms of Susac Syndrome take a lot more time and treatment to go away. The mainstay of treatment for Susac Syndrome is immunosuppressive treatment with steroids.
The reason behind Susac Syndrome being considered rare is because this condition is often at times misdiagnosed as atypical multiple sclerosis but with more and more cases of this condition being reported there is an increased awareness in the medical fraternity about Susac Syndrome.
This is basically an autoimmune condition in which an individual’s immune system attacks and injures the endothelium which results in swelling of the endothelial cells causing partial or complete blockage of the vessels of the brain, retina, and the inner ear resulting in the characteristic symptoms of what we term as Susac Syndrome.
What are the Causes of Susac Syndrome?
As stated, Susac Syndrome is an autoimmune disorder in which the affected individual’s immune system attacks the endothelium or the tiny blood vessels which provide blood to the brain, retina, and inner ear. This results in swelling of the endothelium causing partial or complete blockage of the vessels of the brain, retina, and inner ear causing Susac Syndrome.
The exact reason as to why the immune mechanism is triggered against the endothelium is still not known resulting in the symptoms of Susac Syndrome.
What are the Symptoms of Susac Syndrome?
The symptoms of Susac Syndrome are quite variable and differ from individual to individual. In most of the cases of Susac Syndrome, all the three forms of abnormality do not occur together meaning that abnormalities in the brain, ear, and eye will not occur at once. Some people with Susac Syndrome may only have ear and eye symptoms and their brain may be totally normal whereas in some cases only the brain may be affected.
In majority of cases of Susac Syndrome, persistent headaches are the first presenting symptom which will then be followed by other symptoms of Susac Syndrome. There may be a host of neurological abnormalities that may develop in an individual with Susac Syndrome like gait abnormalities, speech abnormalities, and cognitive impairment. The individual may also exhibit personality and behavioral changes as a result of the encephalopathy caused by Susac Syndrome.
The abnormalities due to branch retinal artery occlusion may range from seeing black spots in the vision to haloing in the field of vision. Visual scotoma may also be experienced by the patient.
Another symptom which will be experienced by an individual with Susac Syndrome is hearing loss which is due to damage to the cochlea or the inner ear. The hearing loss may be partial or complete as a result of Susac Syndrome.
How is Susac Syndrome Diagnosed?
The diagnosis of Susac Syndrome begins with a detailed history of the patient and a thorough clinical evaluation which will involve evaluation by an ophthalmologist as well as an audiologist to check the status of the eye and the ears.
Additionally, specialized tests will be conducted to confirm the diagnosis of Susac Syndrome and to rule other causes of the symptoms. A detailed neurological evaluation will also be conducted to check for neurological changes which are classic for someone with Susac Syndrome.
An MRI of the brain will be conducted which will clearly show changes in the corpus callosum pointing towards Susac Syndrome. An ophthalmologic evaluation will entail checking of the visual fields of the patient which will clearly show the retinal artery occlusion obscuring the patient’s vision.
An audiology test will confirm inner ear dysfunction with damage to the cochlea thus fulfilling all the three characteristics and confirming the diagnosis of Susac Syndrome.
It should be noted here that when the patient first presents to the physician then he or she may not have all the symptoms which are suggestive of Susac Syndrome and this makes the diagnosis more difficult of Susac Syndrome.
How is Susac Syndrome Treated?
In most of the cases, Susac Syndrome is self limited and requires no particular treatment. The encephalopathy caused by Susac Syndrome resolves by itself within a span of one to four years, although early intervention may speed up the recovery process and also help avoid any permanent neurological deficits, or potentially any visual or hearing loss which may become irreversible if early treatment is not given.
Immunosuppressive agents and steroids are the front line treatment for Susac Syndrome. Intravenous gammaglobulins are also quite effective in treatment of Susac Syndrome.
Additionally, CellCept, Imuran, and rituximab have also shown quite a bit of effectiveness in the treatment of Susac Syndrome. For individuals with significant hearing loss, a hearing aid might be prescribed to allow them to hear normally along with the treatments mentioned above for Susac Syndrome.
- Journal of Neuro-Ophthalmology. (2016). The Spectrum of Susac Syndrome: A Case Series. https://journals.lww.com/jneuro-ophthalmology/Fulltext/2016/12000/The_Spectrum_of_Susac_Syndrome__A_Case_Series.3.aspx
- Orphanet. (2021). Susac Syndrome. https://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=840&Disease_Disease_Search_diseaseGroup=Susac-Syndrome&Disease_Disease_Search_diseaseType=Pat&Disease(s)/group%20of%20diseases=Susac-Syndrome&title=Susac-Syndrome&search=Disease_Search_Simple
- Susac syndrome is a relatively rare disorder characterized by three main problems: https://rarediseases.org/rare-diseases/susacs-syndrome/
- Susac syndrome: clinical characteristics, clinical classification, and long-term prognosis https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5089114/