Hypotonia as a central motor disorder.

Hypotonia in childhood may arise because of dysfunction across the neuroaxis. Hypotonia is termed central when it arises because of dysfunction of the central nervous system, in contrast to peripheral hypotonia which is due to neuromuscular disorders. Central hypotonia predominantly affects the axial region of the body and is the most common form of hypotonia. For many children and young people a mixed picture is seen, with some elements of inappropriately high or low tone coinciding. This review explores the pathophysiological mechanisms of central hypotonia, focusing particularly on the role of descending motor pathways and the cerebellum as potential avenues for intervention. A case is made that hypotonia is an underappreciated and underexplored component of the central motor disorder.