Spasticity

Spasticity is a feature of altered skeletal muscle performance in muscle tone involving hypertonia; it is also referred to as an unusual "tightness", stiffness, and/or "pull" of muscles. The word spasm comes from the Greek word, σπασμός (spasmos), meaning to pull or drag.

Clinically spasticity is defined as velocity dependent resistance to stretch, where a lack of inhibition results in excessive contraction of the muscles, ultimately leading to hyperflexia (overly flexed joints). It mostly occurs in disorders of the central nervous system (CNS) impacting the upper motor neuron in the form of a lesion, such as spastic diplegia, but it can also present in various types of multiple sclerosis, where it occurs as a symptom of the progressively-worsening attacks on myelin sheaths and is thus unrelated to the types of spasticity present in neuromuscular cerebral palsy rooted spasticity disorders.