Susak's syndrome: what is it, symptoms, treatment, prognosis

What is Susak Syndrome?

Susak syndrome - a relatively rare disease characterized by three main problems: impaired brain function (encephalopathy), partial or complete blockage (occlusion) of small arteries and capillaries that supply blood to the retina (occlusion of the retinal arteries) and inner ear disease (especially loss of hearing).

Three main forms of Susak's syndrome have been identified. In one form, encephalopathy is a major problem. In the second form, the main problems are occlusion of the retinal arteries and hearing loss, and brain diseases are practically absent. In the third form, encephalopathy is the main problem in the beginning, but repeated episodes of occlusion of the retinal arteries become the main problem after the encephalopathy subsides. The encephalopathic form of Susak's syndrome often resolves within 1-3 years. Other forms tend to be longer, more chronic, or more relapsing (3–10 years or more). All forms require immunosuppressive treatment while the disease is active.

Although considered rare, Susak's syndrome is increasingly found in people around the world, and its true frequency in the general population is unknown. This is because the disease can be misdiagnosed, often as "atypical" multiple sclerosis.

Susak syndrome is autoimmune disease, in particular autoimmune endotheliopathy. Autoimmune means that a person's own immune system mistakenly attacks their own tissues. "Endotheliopathy" is any disease that involves damage to the endothelium, which is a thin layer of cells lining the inner walls of blood vessels. In Susak syndrome, a person's own immune system mistakenly attacks the endothelial lining the smallest blood vessels (capillaries, venules and arterioles) in the brain, retina and internal ear. When endothelial cells are damaged, they tend to swell, and this swelling of the endothelial cells plays a role a key role in partial or complete occlusion (blockage) of tiny vessels in the brain, retina and internal ear. This blockage leads to a decrease in blood flow through the vessels and, therefore, to a decrease in the delivery of oxygen and nutrients to the brain, retina and internal ear - which leads to either temporary dysfunction or irreversible damage to these three organs, depending on the severity and duration of the reduced blood flow.

Signs and symptoms

The specific symptoms, severity, and outcome of Susak syndrome vary from person to person. Typically, not all three major features (encephalopathy, retinal artery occlusion, and hearing loss) are present early in the disease, and all three do not necessarily develop in all patients. When patients are examined by a doctor for the first time, any of the three main signs may be the only one, and one or both of the other signs appear later.

In many patients, headaches (including migraine-like) precede the development of other symptoms of Susak's syndrome. Various additional neurological manifestations may develop:

• cognitive dysfunction (including memory loss, confusion, and decreased executive function);
• violation of gait;
• slurred speech (dysarthria).

Some people develop psychiatric symptoms such as paranoia, personality or behavior changes. The specific neurological symptoms that develop may differ from person to person.

Occlusion of a retinal branched artery can cause the patient to notice a "dark spot" or "black area" in the field of view; or some patients describe a “curtain or shadow drawn” over part of their vision. The medical term for these symptoms is scotoma. These symptoms are caused by damage to the retina due to blockage of blood flow. The retina is a thin layer of nerve cells that receive light and convert it into nerve signals, which are then transmitted to the brain through the optic nerve. Both eyes can be affected in patients with Susak's syndrome. Irreversible visual impairment may occur. Retinal artery occlusion can occur early in some people or later in the course of the disease in others.

Many patients with Susak syndrome experience hearing loss due to damage to a small cochlear-shaped organ in the inner ear. The snail converts sound into nerve impulses that are sent to the brain. Damage to the cochlea is caused by blockage of blood flow in the small vessels that carry blood to the cochlea. Hearing loss in Susak syndrome is generally low and usually occurs relatively suddenly. May affect both ears (bilateral). Its severity can range from mild to severe. In severe cases, cochlear implantation is necessary. In some cases, hearing loss occurs before other symptoms of Susak syndrome develop. Hearing loss is often accompanied by severe ringing in the ears (tinnitus). The vestibular apparatus, also located in the inner ear, can also be affected by microvascular endotheliopathy of Susak's syndrome, leading to dizziness.

The encephalopathic form of the disease usually resolves on its own (i.e., eventually goes away on its own), but it may take a long time to resolve and may recur. It usually lasts 1-3 years, during which time people may experience fluctuating symptom levels (relapsing-remitting). Although the encephalopathic form eventually resolves on its own, treatment is needed to prevent or minimize the damage that can occur during active illness. Relapse after a long period of remission is rare but can occur.

Causes

Susak syndrome is an autoimmune endotheliopathy, a condition in which the body's immune system mistakenly attacks the inner lining (endothelium) of the walls of very tiny blood vessels that supply blood to the brain, retina and inner ear. The exact underlying reason why this is happening is unknown. It is also unclear why the microvessels of the brain, retina, and inner ear are primarily affected. The skin can also be affected.

Affected populations

Susak's syndrome mainly affects young women between the ages of 20 and 40, but occurs in people between the ages of 9 and 72. Women are affected three times more often than men. Although considered a rare condition, Susak's syndrome is increasingly found worldwide and may be more common than originally thought. However, because the disorder is often misunderstood or misdiagnosed, it is difficult to determine the true frequency of the disorder in the general population.

Until now, it has not been proven that the disorder is more common in any particular ethnic group. groups, but early evidence suggests the disease may be more common in Caucasian populations race.

Susak syndrome was first described in the medical literature in 1979 by Dr. John Susak.

Symptomatic disorders

The encephalopathic form of Susak's syndrome is often mistaken for multiple sclerosis (MS) or acute disseminated encephalomyelitis (ADEM). When Suzak syndrome manifests itself primarily with hearing loss, tinnitus and dizziness, it is often mistaken for Meniere's disease.

• Multiple sclerosis - a chronic disease of the central nervous system (CNS), which causes destruction of the integumentary layer (myelin sheath) of the nerves. It is a demyelinating disease. The course of the disease is variable; it may progress, relapse, weaken, or stabilize. Demyelinating plaques or spots scattered throughout the central nervous system impair the ability of nerves to communicate (neurotransmission) and can cause a wide range of neurological symptoms, including speech impairment, numbness or tingling in the extremities, and difficulty walking. Bladder and bowel dysfunction may also be present.
• Acute disseminated encephalomyelitis (ADEM) is a disease of the central nervous system characterized by inflammation of the brain and spinal cord caused by damage to the fatty membrane (myelin) surrounding the nerves. ADEM can occur spontaneously, but usually after a viral infection or vaccination, such as a bacterial or viral vaccine. ADEM symptoms usually develop quickly and may include fever, headaches, vomiting, and fatigue. In severe cases, may develop epilepsy or coma. Loss of vision can also occur due to inflammation of the optic nerve.
• Meniere's disease Is a rare condition that affects the inner ear. Meniere's disease is characterized by periodic bouts of dizziness; fluctuating, progressive, low-frequency hearing loss; ringing in the ears (tinnitus); and a feeling of fullness or pressure in the ear. The disease usually affects only one ear. As with Susak's syndrome, hearing loss in Meniere's is caused by damage to the cochlea. The exact cause of Meniere's disease is unknown.

Diagnostics

The likelihood of Susak's syndrome is increased when a patient has one or more components of the clinical triad (encephalopathy, retinal artery occlusion, hearing loss). The diagnosis of a definite or probable Susak syndrome is based on the presence of at least two components of the triad and documentary evidence of typical lesions of the corpus callosum on MRI brain. The diagnosis process includes a detailed history of the patient, a thorough assessment of all possible explanations for the disease and a variety of specialized tests, including magnetic resonance imaging (MRI), fluorescence angiography, and audiogram.

A complete neurologic and ophthalmologic examination is required to make a diagnosis of Susak's syndrome. A neurologic examination may reveal symptoms and / or signs of brain dysfunction. An eye examination should include a visual field test to determine if the patient has retinal artery occlusion. Patients often continue to have 20/20 vision even after retinal artery occlusion.

MRI uses a magnetic field and radio waves to produce cross-sectional images of selected organs and tissues of the body. In patients with Susak syndrome, MRI usually shows characteristic changes in the brain, especially in the corpus callosum, which is the structure that connects the right and left halves of the brain. The most common MRI abnormality is the presence of lesions ("lumps" or "holes") in the central corpus callosum. These lesions are best seen on T2 FLAIR sagittal images of the corpus callosum.

People with suspected Susak syndrome need a fluorescein angiogram (FA) even if they have no eye symptoms. Fluorescence angiography is an eye test that uses a special dye and camera to assess blood flow (circulation) in the retina. In the disorder, FA abnormalities include: evidence of partial or complete occlusion of a retinal artery; hyperfluorescence of the walls of blood vessels (increased intensity of staining of the walls of blood vessels with a dye); dye leak; and chronic changes in the periphery (loss of capillaries, neovascularization, microaneurysms) with the possibility of vitreous hemorrhage.

Individuals with Susak syndrome should also have a hearing test (audiogram) to detect any hearing loss. All patients with suspected Susak syndrome should have an audiogram, even if they have not noticed any inner ear problems.

The difficulty of making a diagnosis is compounded by the fact that any of the components of the clinical triad can be the first and only component present when patients first seek medical help. This contributes to the likely underreporting of the disorder.

Standard treatments

Although Susak's syndrome can sometimes resolve spontaneously, early, aggressive enough, and appropriately prolonged treatment while the disease is active to avoid or minimize potential irreversible damage to the brain, retina, and inner ear. The two main methods of therapy currently are drugs that suppress the activity of the immune system (immunosuppressants) - corticosteroids (eg, prednisone) and intravenous immunoglobulins (IVIG).

Additional medications may also be required. Additional drugs that have been used to treat patients with Susak syndrome include mycophenolate mofetil (Cellsept), azathioprine (Imuran), cyclophosphamide, rituximab, and anti-TNF therapy. The choice of treatment depends on the severity of the disease.

Hearing aids may be indicated for people with significant hearing loss. For patients with profound hearing loss, cochlear implantation may be helpful.

Forecast

The disease usually resolves in 2-4 years. Late relapses have been reported decades later. The end result shows great variability in disability, ranging from disability to dementia, deafness, and blindness. Most patients persist with varying degrees of cognitive, visual and / or auditory impairment.