Spastic diplegia, historically known as Little's disease, is a form of cerebral palsy (CP) that is a chronic neuromuscular condition of hypertonia and spasticity—manifested as an especially high and constant "tightness" or "stiffness"—in the muscles of the lower extremities of the human body, usually those of the legs, hips and pelvis. Doctor William John Little's first recorded encounter with cerebral palsy is reported to have been among children who displayed signs of spastic diplegia.