14 - Multiple sclerosis

Summary

Introduction

A large part of neurological disabilities of the young adult population of developed countries is due to multiple sclerosis. The number of persons affected by MS is at least 250,000 in the United States and of the same order in the European Union, this latter estimate being based on numerous studies conducted in individual European countries. With few exceptions, onset of MS occurs between 15 and 50 years, with a marked peak between 25 and 35 years. The disease is more frequent in women than in men; the female/male ratio ranges from 1.5 to 2.0.

Macroscopically, the pathology of MS is characterized by lesions widely distributed in the white matter of the brain and spinal cord. Microscopic examination of the lesions shows the typical breakdown of the myelin sheath. The MS lesions have a perivenous distribution. They contain macrophages and lymphocytes, and small amounts of myelin basic protein.

All neurological functions are affected by MS; subsequent disabilities include assistance required for walking, bladder dysfunction, loss of visual acuity. Until now, no treatment has a definitively established durable effect on disease course.

This short chapter will not be an extensive review on MS. It will focus on the most prominent features of the etiology, natural history, and treatment of the disease.

Etiology

There is strong evidence that MS is an immune disease, but its cause and pathogenesis are unknown. However, hundreds of epidemiological studies on MS prevalence which have been conducted throughout the world (approximately 200 were recorded as early as 1980) provide evidence that the disease involves the interplay of genetic susceptibility factors and environmental exposures, possibly to infectious agents.