Paratonia or gegenhalten is classified as a form of hypertonia

Hypertonia

Hypertonia a condition marked by an abnormal increase in muscle tension and a reduced ability of a muscle to stretch. It is caused by lesions to upper motor neurons in the central nervous system, which carry information from the central nervous system to the muscles and control posture, muscle...

 with an involuntary variable resistance (i.e. reduced ability of a muscle to stretch) during passive movement (i.e. a movement without effort). Paratonia develops during a period of dementia

Dementia

Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...

 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

Spastic diplegia

Spastic diplegia, historically known as Little's Disease, is a form of cerebral palsy that is a neuromuscular condition of hypertonia and spasticity in the muscles of the lower extremities of the human body, usually those of the legs, hips and pelvis...

 and similar forms of cerebral palsy

Cerebral palsy

Cerebral palsy is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement....

.