What is peripheral neuropathy?

Peripheral neuropathy is a nervous system condition that causes numbness, tingling, and muscle weakness by involvement of the nerves, that is, neural conducting tissue outside the brain and spinal cord.

Why are Vietnam veterans concerned about peripheral neuropathy? Is it caused by Agent Orange/dioxin?

Some Vietnam veterans have been diagnosed with peripheral neuropathy and others have expressed concern about developing this condition. Some scientific literature has linked peripheral neuropathy to exposure to dioxin, which was contained in Agent Orange.

On May 23, 1991, the Veterans' Advisory Committee on Environmental Hazards considered the relationship between exposure to dioxin and the development of this condition. The Committee concluded that there is a "significant statistical association" between peripheral neuropathy and exposure to dioxin. The Committee qualified this opinion, stating that the association could be said to exist in the absence of exposure to chemical substances known to cause this disorder. Committee members indicated that other risk factors that must be considered are age and whether the individual suffers from other known causes of peripheral neuropathy such as diabetes, alcoholism, or Guillain-Barre syndrome. The Committee also advised that the disorder must become manifest within ten years of the last known dioxin exposure.

What did the Department of Veterans Affairs (VA) do in response to the Advisory Committee's finding and the subsequent report released by the National Academy of Sciences in July 1993?

On July l, 1991, Secretary of Veterans Affairs Derwinski announced that VA will propose rules granting service-connected disability status to certain veterans with peripheral neuropathy. Proposed rule implementing the Secretary's decision was published for public comment in the Federal Register in January 1992. (See 57 Fed. Reg. 2236, January 21, 1992). It was anticipated that the final rule would be published in 1993.

However, in July 1993, when the National Academy of Sciences (NAS) released its comprehensive report, entitled veterans and Agent Orange - Health Effects of Herbicides Used in Vietnam, peripheral neuropathy was not included in the category "sufficient evidence of an association" or "limited/suggestive evidence of an association." Rather, the NAS reviewers concluded that there is "inadequate or insufficient evidence to determine whether an association exists between exposure to herbicides (2,4-D; 2,4,5-T and its contaminant TCDD; cacodylic acid; and picloram) and disorders of the peripheral nervous system." The NAS report added, "Although many case reports suggest that an acute or subacute peripheral neuropathy can develop with exposure to TCDD and related chemicals, reports with comparison groups do not offer clear evidence that TCDD exposure is associated with chronic peripheral neuropathy. The most rigorously conducted studies argue against a relationship between TCDD or herbicides and chronic neuropathy."

VA asked the NAS, in its follow-up report, to consider the relationship between exposure to herbicides and the subsequent development of the acute and subacute effects of peripheral neuropathy (as compared to the chronic effects which were focused on in the initial report).

In January 1994, VA published a notice in the Federal Register that Secretary Brown has determined that a presumption of service connection based on exposure to herbicides used in Vietnam is not warranted for a long list of conditions identified in the NAS report. Peripheral neuropathy was included in this list. (See 59 Fed. Reg. 341, January 4, 1994).

What did the NAS 1996 update conclude about peripheral neuropathy?

When the NAS reviewers separated chronic persistent peripheral neuropathy from acute and subacute transient peripheral neuropathy, they found that there was still inadequate or insufficient evidence of an association between exposure to herbicides and chronic persistent peripheral neuropathy. On the other hand, they reported that there is some evidence to suggest that "neuropathy of acute or subacute onset may be associated with herbicide exposure." They included acute and subacute transient peripheral neuropathy among those conditions they placed in their second category "limited/suggestive evidence of an association." (Chronic persistent peripheral neuropathy remained in category three, "inadequate/insufficient evidence to determine whether an association exists.")

What was VA's response to the NAS 1996 finding about acute and subacute transient peripheral neuropathy?

After careful review of the report, Secretary Brown decided that VA should add acute and subacute peripheral neuropathy (when manifested one year of exposure) to the list of conditions recognized for presumption of service connection for Vietnam veterans based on exposure to herbicides. President Clinton announced this, along with other, decisions, at the White House, on May 28, 1996. The proposed rule was published for public comment in the Federal Register in August 1996. (See 61 Fed. Reg. 41368, August 8, 1996). The final rule was published in the Federal Register in November 1996. (See 61 Fed. Reg. 57587, November 7, 1996).

Where can a veteran get additional information about peripheral neuropathy?

Information regarding peripheral neuropathy and related matters can be obtained at VA medical center libraries, from the Registry Physicians at every VA medical center, or from the Environmental Agents Service (131), Department of Veterans Affairs, 810 Vermont Avenue, N.W., Washington, DC 20420.