Symptoms and signs caused by neural plasticity

Plastic changes in the central nervous system are associated with hyperacti vity, hypersensitivity, and spread of activity including activation of brai n regions that are not typically involved. Symptoms and signs such as neuro pathic pain and tinnitus and hyperactive disorders such as muscle spasm and synkinesis may result from such changes in function. Plastic changes that cause symptoms of diseases can be initiated by novel stimulations, overstim ulation, or deprivation of input and the induced changes in the function of central nervous system structures may persist and aggravate after these ev ents have ceased if the condition is not reversed. Disorders that are cause d by neural plasticity are potentially reversible with treatment. However, the absence of morphologic abnormalities makes diagnosis of these condition s difficult and their treatment has been hampered by lack of understanding of their pathophysiology. Here the role of neural plasticity in the pathoph ysiology of several disorders is reviewed.