Toxic Neuropathies is a very large subject and we will deal only with a few issues in this article.
In a conversation I had with Dr. Waden Emery, MD FAAN Neuromuscular Neurologist, we discussed diabetic neuropathy and the many unanswered questions about the cause, as it is now thought the culprit may not be the high glucose levels, especially since pre-diabetic neuropathy is well documented, and lowering glucose levels may or may not reduce the symptoms, but other chemicals or genetics may be involved in such neuropathies.
Toxic chemicals such as those used in chemotherapy play a major role in causing what is known as chemo-induced neuropathy but even these impact patients at different levels of severity. There is so much we do not know and in the past, there have been many assumptions about toxic chemicals and toxic neuropathies that have just proven to have exceptions to the logic and conclusions.
Peter D. Donofrio, M.D. is professor of Neurology and director of the Neuromuscular Division of the Department of Neurology at Vanderbilt University Medical Center. He is director of Neuropathy Center at Vanderbilt. Excerpts from his excellent article “Medication Induced Neuropathy” are printed below.
In the article by Dr. Donofrio, specifically notes the limits of the blood-brain barrier are slowly being discovered through research on many disease processes, medications, and the influence of genetics or metabolic factors in the vulnerability of some patients to certain disease conditions.
For years the concept of the blood brain barrier or the nerve blood barrier has been misused by even expert neurologists to deny toxic herbicides cause neuropathy whether it is Agent Orange (Vietnam War), some medications or other toxins.
Today, some leaders in the field continue to state that there is nothing to support the statement that the toxic chemicals and herbicides using in the Vietnam War, which included arsenic as in Agent White, affect or damage the Peripheral Nerves. Arsenic is well known to attack the peripheral nerves especially in long term exposure as was true in Vietnam. Let us just state categorically that in 2010 the Institute of Medicine lead a Board of experts, Chaired by the renowned expert on toxins at Harvard University, the Harvard Public Health expert, Dr. Robert Herrick stated that it does. Here is the statement from the report:
“Neurological disorders due to toxicant exposure may result in either immediate or delayed dysfunction of any component of the nervous system; immediate effects of toxicants may involve all aspects of the nervous system, whereas delayed effects are likely to produce more focal problems. Defuse damage to the central nervous system may cause alternations in thinking, consciousness, or attention, often in combination with abnormalities in movement. Focal dysfunction can cause myriad syndromes, depending on which area is damaged.”
In recent articles in the Journal of the Peripheral Nervous System, it is noted that the blood brain or the blood nerve barrier do not in fact work perfectly and often does not prevent damage to the peripheral nerves or even the brain as originally thought. Yet the truth is that one of the challenges of medical research in bringing drugs to target a disease, is the challenge of getting past these barriers! One could call this a catch 22.
The fact of the role of genetics and metabolic factors are noted by Dr. Norman Latov in his book for patients, noting that they play an important role in a patient’s susceptibility to certain neuropathies.
The Veterans Administration now recognizes birth defects in children born of veterans who were exposed to toxic herbicides or Agent Orange and this is becoming a very large issue. Bills in Congress (HR 5484 – Toxic Exposure Research Act of 2014) and with the help of the Vietnam Veterans of America we are going to push to have every Senator and Representative list as co-sponsors of this bill. We now know that these toxic chemicals do change the cells and DNA especially in women Veterans which affect the new born child. To see a list of the VA recognized birth defects, download and print a copy of The VVA Self Help Guide .
Dr. Donofrio states “The peripheral nerves are protected by a blood-nerve barrier and might be perceived to be at a lessened risk than other organs for toxicity. Certain patients, however, may be at a higher risk for developing peripheral nerve toxicity due to genetic or metabolic factors.