Description, Causes and Risk Factors:
Susac syndrome is a rare disease characterized by microangiopathy involving the arterioles of the brain, retina and cochlea. Encephalopathy, recurrent multiple retinal arterial occlusion and hearing loss, without systemic manifestation, are observed in healthy people of middle age, predominantly women. This syndrome was first described by Professor Susac, and since then less than 100 cases were reported in the literature worldwide.
Etiology and pathogenesis of this microangiopathy are still not completely understood. Factors contributing to the occurrence of the syndrome are unknown. Its pathogenesis has not been elucidated either.
One of the hypotheses assumes that a viral infection (with an unknown pathogen) can be a cause of an autoimmune reaction leading to microvascular injury. The presence of antiphospholipid antibodies, factor V Leiden mutation and protein S deficiency have been observed. It still has not been explained why, in the majority of patients, the pathologic process is restricted to blood vessels in the brain, eyes and ears. However, some patients develop systemic symptoms, and changes can be observed in small blood vessels in muscle tissue bioptates, which suggests a systemic character of the disease, with a predisposition towards a triad characteristic of this syndrome.
Brain biopsies, anatomic observations and responses to immunosuppressive therapy suggest that the disease has an autoimmune basis, leading to small vessel vasculitis causing microinfarcts in retina, brain and in the apical turn of the cochlea. Vasospastic arterial occlusions and microembolization seem unlikely. The distribution of arteriolar disease affecting brain, eye and ear is also an enigma.
A high index of suspicion, leading to early recognition of this syndrome is important because treatment with immunosuppression may minimise permanent cognitive, audiologic and visual sequelae. This syndrome has a good prognosis when treated early. In patients whom early diagnosis has led to early administration of immunosuppressive therapy, recovery can be almost complete.
The initial symptoms are headache, often severe, followed by cognitive changes, confusion, and memory and psychiatric disturbance due to encephalopathy. Visual impairment is present in different levels depending on the retinal arterial branch affected. Hearing loss due to cochlear involvement completes the triad. Sometimes the triad may become complete only after a delay of weeks to years. Its frequency is unknown and usually presents with a monophasic self-limited course lasting from months to years, however polycyclic and chronic courses are also related. Although, some patients recover with little or no residual disease, others are deeply impaired with cognitive deficits, gait disturbance and hearing loss.
It is believed that Susac syndrome is frequently underdiagnosed and usually misdiagnosed as multiple sclerosis or acute disseminated encephalomyelitis. The ophthalmic evaluation is important for correct diagnosis, enabling prompt and appropriate therapy to avoid dreaded sequelae.
Ophthalmologic examination is extremely important to confirm diagnosis, differentiating this disease from others systemic illnesses such as multiple sclerosis, migraine, Behcet's disease, systemic lupus erythematosus, acute and chronic encephalitis, thromboembolic stroke.
There is no consensus on treatment of Susac syndrome. It is difficult to evaluate the results of treatment in consequence to its tendency to improve spontaneously.
In some patients monotherapy is effective using glucocorticosteroids, cyclophosphamide and immunoglobulins. In other patients concurrent use of these agents in various combinations has good outcomes. Positive effects of plasmapheresis and hyperbaric oxygen have also been reported.
In some patients, disease remission is obtained by using high doses of intravenous glucocorticosteroids. However, additional therapy in the form of intravenous immunoglobulins, mycophenolate mofetil or cyclophosphamide becomes sometimes necessary. There are also suggestions that treatment of this syndrome may involve monoclonal antibodies used while treating malignant lymphomas, which selectively bind with the CD20 antigen present in maturing lymphocytes B (rituximab).
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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