PB and pesticides. Symptoms possibly indicative of neuropathy were not associated with self-reports of immunizations or chemical exposures however (conclusion stated in paper but data not presented). Electrophysiologic studies were not performed.

Summary and Conclusions

Several well-designed studies from the United States, United Kingdom, and Australia found no evidence of excess peripheral neuropathy in Gulf War veterans. Several other secondary studies supported a conclusion of no excess risk. Some studies, such as that of Cherry et al. (2001a), did report higher rates of peripheral neuropathy, but they used self-reports, which the committee did not accept as a reliable measure of peripheral neuropathy. Furthermore, because researchers use different case definitions of peripheral neuropathies, there are problems of ascertainment, which makes comparisons among groups difficult.

The committee finds no increase in the prevalence of peripheral neuropathy in deployed versus nondeployed veterans, as defined by history, physical examination, and electrophysiologic studies. Detailed quantitative analyses to investigate small-fiber polyneuropathy have not, as yet, been reported in Gulf War veterans.

Therefore the committee concludes that there is limited/suggestive evidence of no association between deployment to the Gulf War and peripheral neuropathy.

Multiple Sclerosis

MS is a chronic inflammatory disease of the brain and spinal cord. It is caused by an immune-mediated attack on the myelin membrane that surrounds and insulates nerve fibers (axons) that are responsible for normal transmission of electrical and chemical information in the nervous system. Strong circumstantial evidence indicates that MS is an autoimmune disease in which normal myelin, and perhaps also nerve cells themselves, are misread as “foreign” by the immune system. Numerous immune cell types—T cells, B cells, and microglia—as well as a variety of immune molecules including antibodies, cytokines, and chemokines are all believed to contribute to destruction of myelin and scarring (gliosis) that are the hallmarks of MS. MS can vary from a relatively benign illness to a rapidly evolving and incapacitating disease. Symptoms of MS—such as weakness of the limbs, numbness, visual loss or blurring, pain, imbalance, fatigue, slowed thinking, and bladder/bowel/sexual dysfunction—reflect the loss of neural connections required for normal function. Treatments are available for many people with relapsing forms of MS; however, no useful therapies exist for progressive symptoms.

MS is a common disease in most parts of the developed world; it affects about 350,000 people in the United States and 2.5 million people worldwide. In Western societies, MS is second only to trauma as a cause of neurologic disability beginning in early to mid adulthood.

MS is approximately three times more common in women than men. The age of onset is typically between 18 and 40 years of age, but the disease can present across the lifespan. MS also appears to be increasing in frequency, especially in women. The environmental factors that lead to MS are not known; however, evidence implicates a lack of sun exposure associated with vitamin D deficiency, and exposure to Epstein Barr virus resulting in a strong antibody response to the virus, as possible contributors.

Several aspects of the Gulf War theater could, in theory, heighten the risk of MS. The first relates to exposure to the hot desert environment. Symptoms of MS may first appear, or can transiently worsen, upon exposure to heat; this is due to the “short-circuiting” of impulses carried

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