Multiple chemical sensitivity (MCS) - Differential diagnosis in clinical neurotoxicology: A German perspective

The multiple chemical sensitivity syndrome (MCS) is a new cluster of enviro nmental symptoms which have been described and commented on for more than 1 5 years now in the USA. In the meantime it has also been observed in Europe an countries. The main features of this syndrome are: multiple symptoms in multiple organ systems, precipitated by a variety of chemical substances wi th relapses and exacerbation under certain conditions when exposed to very low levels which do not affect the population at large. There are no lab ma rkers or specific investigative findings. In our view, MCS is not a separat e clinical syndrome but a collective term. A very small part of the patient s in question may actually exhibit a somatic or psychosomatic response to l ow levels of a variety of chemicals in the environment. For another part, e ven if the MCS symptoms are induced by chemical substances in the environme nt, the basic hypersensitivity is a psychological stress reaction. In the t hird and largest group, the patients have been misdiagnosed, i.e. a somatic or psychiatric disease has been overlooked. There is a fourth group of pat ients in whom there is no evidence of any exposure at all but instead a bel ief system installed by certain physicians, the media and other groups in s ociety This paper tries to describe the neurological and neurotoxic aspects of MCS problems and to illustrate it with examples of an alleged outbreak of chronic neurotoxic disease caused by pyrethroids in Germany. Research st rategy should establish clearly determined diagnostic criteria, agreement o n the use of specific questionnaires as well as clinical and technical diag nostic procedures, prospective clinical studies of MCS patients and compara tive groups as well as experimental approaches. (C) 2000 Inter Press, Inc.