Collateral System is the functional network to keep the entatic state of the body. Collateral disease is characterized by the stagnation of the system. Pathogen invasion of the collateral signalized the development and intensification of the disease

which is mainly expressed by the pathological changes of blood stasis

stagnation by deficiency and toxic factor. The research was started with the vascular dementia and diabetes vascular lesion. It was discovered that the pathologic changes of pathogen invasion in the blood or the collateral not only existed in choronic cases but also in emergency cases. One of the pathophysiologic bases of collateral disease was inferred as the endothelial and the interaction disturbance between blood vessel and blood constituents.