From the Guidelines
Rigidity and spasticity are two distinct types of muscle tone abnormalities with different characteristics, underlying causes, and treatment approaches. The key difference between rigidity and spasticity lies in their response to passive movement: rigidity involves continuous resistance throughout the entire range of motion, whereas spasticity is velocity-dependent, with faster stretching causing increased resistance, followed by a sudden decrease in resistance, known as the "clasp-knife" phenomenon 1.
Characteristics of Rigidity and Spasticity
- Rigidity is often described as "lead-pipe" or "cogwheel" resistance and typically results from basal ganglia disorders, such as Parkinson's disease, affecting flexor and extensor muscles equally.
- Spasticity, on the other hand, results from upper motor neuron lesions, such as those seen in stroke, multiple sclerosis, or spinal cord injury, and predominantly affects anti-gravity muscles.
Treatment Approaches
- Treatment for rigidity often involves dopaminergic medications, such as levodopa or dopamine agonists.
- In contrast, spasticity is managed with muscle relaxants, like baclofen, tizanidine, or botulinum toxin injections, as well as physical therapy to maintain range of motion and function, as noted in the management of spasticity in stroke survivors 1.
Clinical Considerations
- It is essential to accurately diagnose and differentiate between rigidity and spasticity to provide effective treatment and improve patient outcomes, particularly in conditions like stroke, where spasticity can lead to contracture, activity limitations, and participation restrictions if left untreated 1.
From the FDA Drug Label
Indications and Usage Baclofen tablets are useful for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity.
The difference between rigidity and spasticity is not explicitly defined in the provided drug label.
- Rigidity and spasticity are mentioned as separate symptoms, but their distinct characteristics are not described. The FDA drug label does not answer the question.
From the Research
Definition and Characteristics
- Spasticity is a velocity-dependent increase in muscle tone and uncontrolled, repetitive, involuntary contractions of skeletal muscles 2
- It is a sign of upper motor neuron lesion, which can be located in the cerebrum or the spinal cord, and be caused by stroke, multiple sclerosis, spinal cord injury, brain injury, cerebral paresis, or other neurological conditions 3
- Spasticity results from interruption of inhibitory descending spinal motor pathways, and although the pathophysiology of spasticity is poorly understood, the final common pathway is overactivity of the alpha motor neuron 4
Comparison with Rigidity
- Rigidity is not explicitly defined in the provided studies, but it can be inferred that it is a different condition from spasticity, as spasticity is specifically mentioned as a velocity-dependent increase in muscle tone, whereas rigidity is not mentioned as such
- Spasticity is characterized by uncontrolled, repetitive, involuntary contractions of skeletal muscles, whereas rigidity is not described in the provided studies
Treatment and Management
- Treatment of spasticity is mostly symptomatic, aimed at relieving muscle hypertonus, thus increasing motor performance and improving nursing 5
- Management of spasticity should be multimodal and should always include physiotherapy or exercise 3
- Oral medications such as baclofen and tizanidine have limited efficacy and considerable side effects, but are easiest to use 3
- Botulinum toxin combined with physiotherapy and/or orthopaedic surgery is effective treatment of localized spasticity 3
- Treatment with intrathecal baclofen via programmable implanted pump is effective in generalized spasticity, particularly in the lower extremities 3