- 1. Stiffness or inflexibility. SYN: rigor (1). 2. In psychiatry and clinical psychology, an aspect of personality characterized by an individual's resistance to change. 3. In neurology, one type of increase in muscle tone at rest; characterized by increased resistance to passive stretch, independent of velocity and symmetric about joints; increases with activation of corresponding muscles in the contralateral limb. Two basic types are cogwheel r. and lead-pipe r.. SEE ALSO: nuchal r.. [L. rigidus, rigid, inflexible]- cadaveric r. SYN: rigor mortis.- catatonic r. r. associated with catatonic psychotic states in which all muscles exhibit flexibilitas cerea.- cerebellar r. increased tone of the extensor muscles, related to injury of the vermis of the cerebellum.- cogwheel r. a type of r. seen in parkinsonism in which the muscles respond with cogwheel-like jerks to the use of constant force in bending the limb.- decerebrate r. a postural change that occurs in some comatose patients, consisting of episodes of opisthotonos, rigid extension of the limbs, internal rotation of the upper extremities, and marked plantar flexion of the feet; produced by a variety of metabolic and structural brain disorders. SYN: decerebrate state.- decorticate r. a unilateral or bilateral postural change, consisting of the upper extremities flexed and adducted and the lower extremities in rigid extension; due to structural lesions of the thalamus, internal capsule, or cerebral white matter. SYN: decorticate state.- lead-pipe r. the plastic type of r. resembling that of a pipe of lead seen in certain forms of parkinsonism.- nuchal r. impaired neck flexion resulting from muscle spasm (not actual r.) of the extensor muscles of the neck; usually attributed to meningeal irritation.- ocular r. the resistance offered by the eyeball to a change in intraocular volume; manifested as a change in intraocular pressure.- postmortem r. SYN: rigor mortis.
* * *a) abnormal stiffness of muscle <muscle \rigidity symptomatic of Parkinson's disease (Diane Gershon)>b) emotional inflexibility and resistance to change
* * *n.(in neurology) resistance to the passive movement of a limb that persists throughout its range. It is a symptom of parkinsonism. The smooth resistance through the whole range of movement is also known as lead-pipe rigidity; with superimposed tremor, as in parkinsonism, it is called cogwheel rigidity. Compare spasticity.
* * *ri·gid·i·ty (rĭ-jidґĭ-te) [L. rigiditas; rigidus stiff] stiffness or inflexibility, chiefly that which is abnormal or morbid; called also rigor.
Medical dictionary. 2011.