What is "paratonia"

n. (context medicine English) A form of hypertonia with an involuntary variable resistance (i.e. reduced ability of a muscle to stretch) during passive movement.

Paratonia or gegenhalten is defined as "a form of hypertonia with an involuntary variable resistance during passive movement." In other words, attempting to move the limb of a person with paratonia will result in that person involuntarily resisting the movement. The amount of resistance is determined by the speed of the movement: faster, more forceful movements will result in greater amounts of resistance. It is also present regardless of the direction of the movement.

Paratonia can be distinguished from spasticity by observing a lack of exaggerated deep tendon reflexes and a lack of a clasp-knife response. It can be distinguished from Parkinsonian (aka "lead-pipe") rigidity in that the amount of resistance in Parkinsonian rigidity does not vary with the velocity of the movement.

Paratonia develops during a period of dementia and the degree of effect is dependent upon the disease's progress.

Paratonia was classified very recently by experts, and is unrelated to the much more typical spasticity associated with spastic diplegia and similar forms of cerebral palsy. also in frontal lobe stroke.