The specific symptoms, severity, and outcome of Susac syndrome vary from one person to another. Commonly, the three main features (encephalopathy, branch retinal arterial occlusions, and hearing loss) are not all present at disease onset, and all three do not necessarily develop in all patients. When patients are first evaluated by a physician, any one of the three main features may be the only feature present, with one or both of the other features appearing only later.
In many patients, Headaches (including migraine-like headaches) precede the development of other symptoms of Susac syndrome. A variety of additional neurological findings may develop: cognitive dysfunction (including memory loss, confusion, and decreased executive function), gait disturbance, and slurred speech (dysarthria). Some individuals develop psychiatric symptoms such as paranoia or personality or behavioral changes. The specific neurological symptoms that develop will vary from one person to another.
Branch retinal artery occlusion (BRAO) can cause the patient to notice a “dark spot” or “ area” in their field of vision; or, some patients describe a “curtain or shade being drawn” over a portion of their vision. The medical term for these symptoms is “scotoma.” These symptoms are due to injury to the retina, because of blocked blood flow. The retina is the thin layer of nerve cells that sense light and convert it to nerve signals, which are then relayed to the brain through the optic nerve. Both eyes can be affected in individuals with Susac syndrome. Permanent impairment of vision may occur. BRAOs may occur early in some individuals or later in the course of the disease in others.
Many individuals with Susac syndrome develop Hearing loss due to damage to the small, snail-shaped organ of the inner ear known as the cochlea. The cochlea converts sound into nerve impulses to be sent to the brain. The damage to the cochlea is caused by the blockage of blood flow through the small vessels that supply blood to the cochlea. Hearing loss in Susac syndrome is primarily at low frequencies and usually occurs relatively suddenly. It may affect both ears (bilateral). Its severity can range from mild to severe. In severe cases, cochlear implantation is warranted. In some cases, Hearing loss may occur before other symptoms of Susac syndrome develop. Hearing loss is often accompanied by intense ringing of the ears (tinnitus). The vestibular apparatus, which is also located in the inner ear, can also be affected by the microvascular endotheliopathy of Susac’s syndrome, resulting in vertigo (dizziness).
The encephalopathic form of Susac syndrome is typically self-limited (i.e., eventually subsides on its own), but may take a long time to resolve and may recur. It usually runs a course of 1-3 years, during which time individuals may experience fluctuating levels of symptoms (relapsing-remitting). Although the encephalopathic form eventually goes away on its own, treatment is necessary to prevent or minimize damage that can occur while the disease is active. Relapse after a long period of remission is rare, but can occur.