Spasticity
Pronunciation: spas-TIS-it-ee
A velocity-dependent increase in tonic stretch reflexes (muscle tone) resulting from upper motor neuron lesions, frequently cited as the clinical indication for tone-managing orthoses.
Full Definition
Spasticity is a motor disorder characterised by a speed-dependent increase in resistance to passive muscle stretch, arising from damage to the corticospinal or other upper motor neuron pathways, as in stroke, cerebral palsy, spinal cord injury, or multiple sclerosis. In orthotic documentation, spasticity serves as a clinical justification for devices that provide sustained, low-load stretch, inhibit pathological reflexes, or maintain joint position against involuntary muscle contraction. Editors must distinguish spasticity from rigidity (which is not velocity-dependent) and from contracture (a structural shortening of soft tissue). The term is often paired with functional descriptors such as 'mild', 'moderate', or 'severe' using validated scale references (e.g., Modified Ashworth Scale).
Usage
Usage note: Do not use as a synonym for 'rigidity' or 'stiffness'. When a scale score is cited, include the full scale name (e.g., Modified Ashworth Scale) on first reference.
In Context
- "Grade 2 spasticity of the left plantar flexors on the Modified Ashworth Scale supported the prescription of a tone-reducing AFO." — Orthotic referral and evaluation report
- "The editor queried the author's use of 'rigidity' where clinical context clearly indicated velocity-dependent 'spasticity'." — Manuscript review comment