Susac syndrome

The symptoms and severity of Susac syndrome can vary person to person. The three main parts of the body that are affected are the brain, eyes, and ears. However, all three body parts are not affected in all people with Susac syndrome.^[1]

A headache is often one of the earliest symptoms of Susac syndrome. Recurrent headaches may be a sign of encephalopathy, or brain disease. Other neurological symptoms may develop including walking difficulties (ataxia), slurred speech (dysarthria), and cognitive changes including memory loss, confusion, and personality or behavioral changes.^[3] In some cases, affected individuals may have urinary dysfunction or muscle pain (myalgia).^[4]

Affected people may also have specific findings in the eyes called branch retinal artery occlusions (BRAO). This occurs when one of the blood vessels that supply blood to the retina (retinal arteries) become blocked. This can cause dark spots in the vision, but some people have no symptoms of BRAO.^[1] 

Susac syndrome can also cause hearing loss due to poor circulation to the ears. Ringing in the ears (tinnitus) may also be present. The ears also have a role in regulating our balance. Therefore, some people with Susac syndrome experience vertigo and feel like their surroundings are spinning.^[1] 

People with Susac syndrome may find that their symptoms go away and return again over a period of years. Other people experience symptoms only once, and after treatment the symptoms go away completely. Although the condition may resolve on its own, some people can develop long-term neurological damage, vision loss, or hearing loss.^[5]

The exact cause of Susac syndrome currently is not known. The condition is thought to be an autoimmune disorder. Autoimmune disorders occur when the immune system (which fights off infections) mistakenly attacks the tissues of the body. When this occurs, it can cause swelling of the small blood vessels that supply blood to the brain, retina, and inner ear. This swelling can cause the blood vessels to completely close up so that parts of the body are not getting enough blood or oxygen. The symptoms of Susac syndrome are caused by damage to small blood vessels and the decreased ability of these blood vessels to carry blood and oxygen.^[1]

To our knowledge, there is no evidence that Susac syndrome is inherited, and no familial cases of Susac syndrome have been reported. Cases described in the medical literature have occurred in people with no known history of the condition in their family.

The diagnosis of Susac syndrome may be suspected based on a thorough clinical evaluation, a detailed medical history, and a variety of specialized tests. These tests may include magnetic resonance imaging (MRI). In people with Susac syndrome, an MRI can show characteristic changes in the brain, especially the corpus callosum. These findings are specific to Susac syndrome.^[6]

A complete eye exam is also done to diagnose Susac syndrome. This eye exam will include a fluorescein angiography, which measures the blood flow through the retina. Other tests include a hearing exam to test for hearing loss and analysis of the cerebrospinal fluid, which may show high protein levels.^[7] 
   
Susac syndrome can mimic several diseases, including multiple sclerosis, acute disseminated encephalomyelitis, chronic encephalitis, aseptic meningitis, Lyme disease, cardioembolic disorder, complicated migraine, systemic lupus erythematosus, Bechet syndrome, sarcoidosis, tuberculosis, syphilis, lymphomas, and Creutzfeldt-Jakob disease.^[3][8][9]

Early, aggressive, and sustained treatment of Susac syndrome is recommended to avoid or minimize neurological damage, hearing loss, and vision loss. Treatment includes medications that suppress the activity of the immune system (immunosuppressive therapy) so that it does not attack the blood vessels in the brain, eyes, and ears. Immunosuppressive medications may include high doses of corticosteroids, cyclophosphamide, and intravenous immunoglobulins. Doctors may also recommend blood thinners such as aspirin in order to prevent clotting in the small blood vessels.^[5] Once treatment has improved symptoms, the medications can be slowly tapered off.^[1]

Alternative treatments such as mycophenolate mofetil may be helpful in cases that don’t improve with other treatment. Overall, medications for Susac syndrome can prevent more symptoms from developing and improve symptoms of the condition, but the treatment may not be able to repair neurological, hearing, or visual damage. In some cases, people with severe hearing loss may benefit from cochlear implants.^[4] 

It can be difficult to predict the long-term outlook for people affected by Susac syndrome. Some people with the condition are only affected by symptoms once in their lives. Other people have symptoms for a couple of episodes, after which time the symptoms go away. Finally, some people have a chronic, relapsing course with frequent flare-ups and remissions.^[6] The condition typically lasts from 2 to 4 years, but may be shorter or longer depending on the person.

Some people recover from Susac syndrome with little or no long-term symptoms, while others continue to have cognitive deficits, gait disturbance, or hearing loss. Vision usually is not seriously impaired. Most patients recover from Susac syndrome. Although they may have some disabilities such as hearing loss, most are able to live as they did prior to experiencing symptoms. There are, however, a couple of reported cases in the literature of people who have died from complications of Susac syndrome.^[10]