Muscle Hypertonia [Disease/Finding] Muscle Rigidity [Disease/Finding] Rigidity, Muscular Muscle Rigidity M0014242 C0026837 D009127 Muscle Rigidity 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) 16046003 C4298 1026262 N0000002060 Muscular Diseases [Disease/Finding]