Concept of spastic hypertonia.

This introductory article highlights the definition of spastic hypertonia, and briefly introduces the reader to the incidence and most frequent causes of spastic hypertonia. The article also discusses the functional losses caused by spastic hypertonia that will be reviewed more thoroughly in the following articles. Also discussed is the neural physiology and the locations of the structural lesions within the central nervous system that are involved in spastic hypertonia, with an emphasis on the different clinical presentations depending on the location of the lesion.