Muscle Hypertonia [Disease/Finding] Muscle Spasticity [Disease/Finding] Muscle Spasticity 221360009 D009128 N0000002061 A form of muscle hypertonia associated with upper MOTOR NEURON DISEASE. Resistance to passive stretch of a spastic muscle results in minimal initial resistance (a "free interval") followed by an incremental increase in muscle tone. Tone increases in proportion to the velocity of stretch. Spasticity is usually accompanied by HYPERREFLEXIA and variable degrees of MUSCLE WEAKNESS. (From Adams et al., Principles of Neurology, 6th ed, p54) C0026838 C4300 M0014243 Muscle Spasticity 1024482 Muscular Diseases [Disease/Finding]