Neurologic diseases are common afflictions, with risk for specific disorders dependant on such factors as age, family history, and environmental exposures. The battlefield environment might be associated with an increase in risk for a variety of neurologic problems. These range from the known consequences of traumatic brain and nerve injury, which can include epilepsy, cognitive disturbances, headache, and nerve or bodily pains, to the likely relationship between battlefield deployment and an increase in risk for amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease). Multiple sclerosis (MS) is another neurologic disorder of interest in this context, as risk for MS has been associated with exposure to highly stressful experiences including war. Immune-mediated neuropathies, including Guillain Barré syndrome, are also known to follow a variety of infectious illnesses or vaccinations to which servicemembers may have been exposed. The special circumstances of the Gulf War theater, with exposures to extreme heat, poor sanitation in some circumstances, exposure to unfamiliar biological agents, as well as known and unknown exposures to drugs such as pyridostigmine bromide (PB), pesticides, fumes, and other environmental toxins might contribute to the development of a variety of neurologic disorders. As examples, peripheral neuropathy or myopathy are known to occur with exposures to a number of different toxins and drugs, and Parkinson’s disease is associated with pesticide exposure. For these reasons, a broad analysis was undertaken to review the literature on a wide range of neurologic outcomes identified to date in servicemembers who participated in the Gulf War mission. The review is organized by specific neurologic afflictions including peripheral neuropathy and myopathy, MS, ALS, and other neurologic disorders. Some common neurologic disorders such as Parkinson’s and Alzheimer’s diseases rarely ever occur until later in life (after age 60), and it is highly unlikely that Gulf War veterans would have developed these disorders to date, even though a very long latency period of decades for such health outcomes is a possibility. Thus current studies have insufficient follow-up time to allow drawing any conclusions on increases of risk for these disorders among Gulf War veterans. Other disorders of unknown but possible neurologic etiology, including chronic fatigue syndrome, fibromyalgia, and multisystem illness, are discussed in other sections.
This section reviews studies of peripheral neuropathy, polyneuropathy, or neuromuscular symptoms, as identified by the investigators’ conducting the studies. Peripheral neuropathy, broadly defined, is a disease of the peripheral nerve tissues (that is, nerve fibers ensheathed by Schwann cells, including nerve roots), which transmit information from the brain and spinal cord to other parts of the body.
Numerous types of peripheral neuropathy have been characterized, each with its own set of symptoms, patterns of development, and prognosis. Peripheral neuropathy can be classified by a variety of factors, such as the population of nerve fibers affected (for example, motor, sensory, or autonomic). Additionally, neuropathy can be classified by the time course (acute, subacute and chronic, remitting, or relapsing) and by pathology (axonal, demyelinating, or other). Peripheral neuropathy might be inherited (for example, resulting from inborn errors in the genetic code or mutations) or acquired (for example, from physical injury, tumors, toxins, autoimmune responses, nutritional deficiencies, alcoholism, vascular and metabolic disorders, or