Unexplained Chronic Illness Martin Pall's compelling conceptualization of the excitotoxic cascade and its pivotal role in both the initiation and the perpetuation of chronic multisystem illnesses one or more short-term stressors chemical sensitivity – pesticides and organic solvents chronic fatigue – bacterial and viral infections fibromyalgia – physical traumas PTSD – severe psychological traumas to which the body responds with an outpouring of excitotoxins (glutamate) inflammatory factors (cytokines and eicosanoids) free radicals (nitric oxide) stress-induced outpouring of endogenous excitotoxins, inflammatory cytokines, and free radicals sets in motion (in certain susceptible individuals) the nitric oxide / peroxynitrite cycle a viciously destructive, self-propagating cycle involving immune stimulation, inflammatory cytokines, membrane destabilization, synaptic overactivity, opening of calcium-permeable channels, massive calcium influx, etc. and culminating in chronic illness