Professor Martin Pall (Professor of Biochemistry and Basic Medical Sciences Washington State University) has developed a theory that:
A Novel Disease Paradigm Produces Explanations for a Whole Group of Illnesses (A Common Causal (Etiologic) Mechanism for Chronic Fatigue Syndrome, Multiple Chemical Sensitivity, Fibromyalgia and Posttraumatic Stress Disorder)
The interesting thing is that malfunctioning NMDA-receptors are an important part of his theory.
If you look at his list of substances that can combat the vicious NO/ONOO-cycle you find almost the same list as the one MSG-sensitive people have found helpful.
A protocol for Chronic Fatige and the other related diseases has been developed based on megadoses of supplements.