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Objectives
After studying this chapter, the student should be able to:
Briefly discuss the epidemiologic aspects of neuroimmunologic diseases.
Understand the basic premise of immunologic diseases involving the central and peripheral nervous systems.
Understand prototypical diseases resulting from immune system damage to the nervous system.
Briefly discuss treatment options available to patients with various neuroimmunologic diseases.
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Although not described as common illnesses, neuroimmunologic diseases account for a significant proportion of disability in mid-to-late life in many developed countries. As a rule, these illnesses typically present with a progressive decline in neurologic function with superimposed flare-ups, resulting in significant neurologic deficits that can make basic functions of life quite difficult to perform. These illnesses are thought to collectively affect >500,000 people in the United States. Because the severity of illness within each disease can vary widely, studies looking at life expectancies can vary, but it is generally accepted that these illnesses result in a reduction of life expectancy that is commensurate with the severity of illness in each case.
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OVERVIEW OF NEUROIMMUNOLOGIC ILLNESS
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The immune system can cause protean manifestations of neurologic disease, and no single description can encompass all of them. To illustrate the range of disorders that the immune systems can cause, 2 classes of disorders will be discussed here in some detail: demyelinating disorders, which include multiple sclerosis (MS) and the related disorders neuromyelitis optica spectrum disorder and transverse myelitis (TM); and the neuromuscular disorders myasthenia gravis (MG) and Lambert-Eaton syndrome. Although this is far from a comprehensive review, these are common disorders and illustrate many of the principals of pathophysiology, diagnosis, and treatment.
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Almost all patients with MS are diagnosed between the ages of 20 and 49 years, with a mean age of diagnosis at 30 years. Approximately 5% of patients are diagnosed prior to age 20 years, and 9% are diagnosed after age 49 years. The disease has a female-to-male ratio of 3:1 and typically presents with acute onset of a neurologic symptom. The exact cause is still unknown. The illness has higher rates of prevalence in higher latitudes (farther distance from the equator), and many feel this may reflect an environmental component. Lack of sunlight exposure and low vitamin D have been proposed to contribute to the disease, but conclusive evidence for this is still lacking. It is generally accepted that there is also a genetic contribution to risk; >120 genes have been implicated as contributory to the development of MS, and almost all of these genes have direct or indirect effects on the immune system.
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There are between 400,000 and 750,000 people living with MS in the United States and 2.3 million people with MS worldwide. This illness has a very high cost to society. The medications ...