Muscle Rigidity

**Definition:** Continuous involuntary sustained muscle contraction which is often a manifestation of BASAL GANGLIA DISEASES. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from MUSCLE SPASTICITY. (From Adams et al., Principles of Neurology, 6th ed, p73)

**Tree numbers:** - C05.651.504 - C10.597.613.550.500 - C23.888.592.608.550.500

**Synonyms:** - Rigidity, Muscular