Neurotoxicology: what the neurologist needs to know.

Correspondence to: Professor John B Harris, Chemical Hazards and Poisons Division, Health Protection Agency, Wolfson Unit, Faculty of Medical Sciences, Newcastle upon Tyne, NE2 4AA; [email protected] _________________________ A search of internet sites offering detoxification programmes for the elimination of toxins from the body and the regeneration or rejuvenation of the immune system, the nervous system as well as blood, liver, and kidney, reveals three features of current popular thinking on toxins: a terrible ignorance of basic science, a poor understanding of the organisation and function of the human body, and an irrational fear of the ‘‘chemicals’’ that prevent us from living to our full potential. Whatever our private thoughts on the expression and exploitation of these fears, we tend to forget that the most complete text on experimental and clinical neurotoxicology lists more than 350 compounds (synthetic and naturally occurring) known to cause functional or structural damage to the nervous system. We should also note that a recent survey of the body load of a number of toxic chemicals in human subjects revealed widespread accumulation of a number of known toxins of considerable clinical interest, including organochlorines, polychlorinated biphenyls (PCBs), and dichlorodiphenyl dichloroethylene (DDE), and the continuing concern of many people over the perceived neurological damage caused, for example, by participation in military operations in the Gulf. Many of the subjects who consider themselves neurologically damaged by exposure to ‘‘toxins’’, ‘‘chemicals’’, or other environmental agents will seek confirmation and reassurance that their concerns are valid, that they have a definable illness, and that their condition will be treated. Considerable numbers are referred to a neurologist or psychiatrist for help. In this article we define a neurotoxin and the science of neurotoxicology, discuss some of the factors involved in the development of the signs and symptoms of neurotoxic damage, and offer advice on the examination of the patient, the diagnosis, and the construction of a management programme (see also Blain and Harris).