Automimune disorders are quite prevalent and they comprise a varied group of diseases with wide ranging damage to multiple organ systems. When the immune system fails to recognize components of the body as being “native” inflammation, usually of the connective tissue, results in symptoms of weakness, muscle pain, fatigue, joint pain, and fever. Our focus here is on one particular type of autoimmune disorder: Systemic Lupus Erythematosus (SLE). Its prevalence is 322,000 and 1.5 million people in the UnitedStates. Exactly how many is unknown since its symptoms can be mistaken for many other diosrders. It occurs nine time more commonly in women than men. IT most often appears in women of childbearing age. Twenty percent of cases are aged over 50 years. And for reasons that are unknown incidence in the last half century has increased ten fold in Western industrialized countries. In Western industrialized countries people of African or Asian descent are 2-4 times more likely to develop SLE than are people of European descent. There is a tendency for the disorder to run in families but the exact genetics of the disorder are unclear. Sex hormones, environmental factors including viral infections, diet, stress, chemical exposures, and sunlight are also thought to play a role in triggering this complex disorder. Certain drug exposures trigger the disorder in 10% of patients, and more than 80 drugs that may be involved have been identified. In people with SLE, cells that have undergone self-destruction (apoptosis) because they are damaged or no longer needed are not cleared away properly. The relationship of this loss of function to the cause or features of SLE is unclear. A characteristic rash that appears across the face, often called “butterfly” rash, was thought in the 18th century to have been caused by a wolf bite. Lupus is Latin for wolf.
Neurologic symptoms associated with SLE present in approximately 75% of patients within the first year of diagnosis. These include psychosis, seizure, stroke, and neuropathy. Stroke may be caused by either direct inflammation of the cranial vessels (vasculitis), or indirectly as a result of damage to the heart valves which is also another manifestation of SLE. Seizures can occur as a result of microinfarcts in the brain. These occur resulting from vasculitis of small and medium size cerebral vessels, thrombosis which occurs when there is antiphospholipid antibodies present in the blood stream. Anticoagulant therapy is needed when the antiphospholipid antibody is present.
Anxiety and depression are also common in SLE. Psychosis associated with lupus is often attributed to the treatment with corticosteroids made necessary by the disorder. It can be difficult to distinguish whether the behavioral manifestations are part of the lupus or due to the steroids. Symptoms can wax and wane over time, and extended periods of remission are common.
The peripheral nervous system is very often involved with the appearance of a mostly sensory distal neuropathy. A demyelinating polyneuropathy can be seen which resembles Guillain Barre Syndrome. Treatment with corticosteroids, immune globulin, and plasmapheresis may be necessary.
In addition to direct injuries to nervous system tissue causing neurologic manifestations of weakness, fatigue and loss of function, the nervous system is also affected indirectly by damage to other organ systems. Because SLE can damage cardiac tissue, valve disorders can lead to stroke as mentioned previously. But in addition, the damage to the kidneys which is very common in SLE results in metabolic derangements that lead to cognitive difficulties, psychosis, and ultimately delirium and dementia.
For the neurologist, diagnosis is often complicated by imaging of the brain which can appear to be similar to Multiple Sclerosis. As there is significant overlap in the symptoms between the two disorders ultimately the distinction relies on the presence of biologic markers as for example the antiphospholipid antibody. As the genetics of transmission become better understood, the diagnosis can be made sooner and the treatment further improved.