What is Muscle Spasticity?
November 6, 2024
Spasticity is one of the many secondary health effects caused by paralysis. People with a spinal cord injury, stroke, cerebral palsy, and multiple sclerosis most often have trouble with muscle spasticity, but it can affect anyone with an upper motor neuron lesion. That includes a wide range of neurological disorders and injuries, and it means that millions of people are affected by spasticity.
When most people think of spasticity, they imagine simple muscle spasms, where a muscle twitches involuntarily. However, spasticity, also known as spastic hypertonia, can be more accurately defined as “disordered sensorimotor control, resulting from an upper motor neuron lesion, presenting as intermittent or sustained involuntary activation of muscles’’ [1], and the effects of spasticity can range from slight muscle stiffness to intense, uncontrollable muscle spasms that can literally launch someone out of their chair.
What Causes Muscle Spasticity?
Upper motor neuron lesions cause spasticity in much the same way that they cause paralysis and loss of feeling – by disrupting communication between the brain, the spinal cord, muscles, and the sensory system (sensory organs in the skin, muscles, tendons, etc.).
Normally, if you want to relax a muscle, you only have to think about it, and your brain will communicate with your muscles through your spinal cord to make them relax. But if your brain or spinal cord is damaged, your muscles never get the message to relax.
For this reason, if anything tells your muscles to activate, like a reflex that makes you pull away from something hot, the activation is often exaggerated or never stops. Spasticity can be triggered by movement, pain, discomfort, posture, and even other medical problems like urinary tract infections and pressure sores.
What Does Spasticity Look Like?
Many people with muscle spasticity have increased muscle tone, meaning that some of their muscles never relax fully and are always somewhat contracted. This increased tone, also known as hypertonia, can range from mild and uncomfortable to severe and debilitating, like rigidity. Hypertonia is most commonly seen affecting the upper limb, resulting in a constantly flexed elbow, bent wrist, and/or a clenched fist.
Figure 1: Presentation of spasticity in the upper limb.
The other common presentation of muscle spasticity is hyperreflexia (exaggerated reflexes). When a reflex arc is activated in someone with spasticity, like when the patellar tendon is struck or you touch a hot stove and recoil, oftentimes the reflex will be exaggerated. In extreme cases, the reflex will repeat itself over and over again, echoing through the nervous system, which is known as clonus. Check out this video to see what hyperreflexia and clonus look like.
Pros and cons of spasticity
While spasticity is a symptom of a neurological disorder, it’s not always a bad thing. The table below lists some of the pros and cons of spasticity.
| Pros | Cons |
| Stiff muscles can help with some activities, like transferring from a wheelchair | Stiff muscles can hinder other activities, like getting dressed or brushing your teeth |
| Controlled reflex spasms can help with some activities, like standing & grasping | Uncontrolled reflex spasms can hinder other activities and lead to injury |
| Hypertonia and spasms work the muscles, preventing atrophy & bone density loss | Spasticity can be uncomfortable and even painful |
| Metabolic requirements of spasms can improve blood circulation and breathing | Extreme hypertonia can lead to joint contractures and pressure sores |
| Spasticity can be a warning sign that something else is wrong, like an infection | Extreme hyperreflexia can lead to injuries from collisions and falls |
For more on the pros and cons of spasticity, check out this video from the University of Washington.
Managing spasticity
If the cons of spasticity outweigh the pros, then treatment may be necessary. There are several options for managing spasticity, each with its own pros and cons:
- Surgery
- Surgery is sometimes used as a last resort to release contractures, lengthen muscles, or reshape joints.
- Pros: Permanent solution
- Cons: Irreversible, painful, potentially dangerous, expensive
- Implanted pump
- An intrathecal pump can be implanted in the body and programmed to automatically deliver anti-spasm medication right where it’s needed.
- Pros: Precise and low-dose so reduced side effects, reversible, refillable
- Cons: Requires surgery, can malfunction, may cause infections, expensive
- Injections
- Chemicals can be injected directly into the muscle to block nerves and eliminate spasticity.
- Pros: Only needed once every few months, directly targets the spastic muscles
- Cons: Effectiveness diminishes over time, expensive
- Medications
- Medications can be taken orally or transdermally (through a patch) to manage spasticity.
- Pros: Non-invasive, easy to manage, more affordable
- Cons: Requires higher doses and affects the whole body with increased side effects
- Stretching and exercise
- The majority of time in inpatient rehab following a spinal cord injury is spent on range of motion (stretching) and strengthening exercises [2], which have a positive effect on spasticity.
- Pros: Easy to do for some people, strengthening can improve function, most affordable
- Cons: Time-consuming, can be difficult without assistance or special equipment
- Electrical stimulation
- Electrical stimulation can activate paralyzed muscles, enabling someone to exercise muscles that they otherwise could not.
- Pros: Reduces the number of spasms, the best way to exercise paralyzed muscles, can have beneficial side effects, can be done without much time and effort, affordable options available
- Cons: Can strengthen muscles, making spasms stronger; may not work well for everyone; can be expensive and complicated
Electrical stimulation and spasticity
There is a lot of confusion out there as to how electrical stimulation can be used to manage spasticity. Arjan van der Salm, a researcher from the Netherlands who wrote his doctoral dissertation on managing spasticity with electrical stimulation, provides a great analysis in his journal paper published in 2006 [3].
He demonstrated that electrical stimulation does not reduce spasticity, but it does relax spasms, meaning that the muscle will spasm less for a period of time, usually for several hours after stimulation. This can be achieved by either stimulating the spastic muscle itself or by stimulating its antagonist. For example, if a person’s calf muscles (triceps surae) are spastic, electrical stimulation can be applied to the calf muscle or to the shin muscles (tibialis anterior), and either will relax the spasms.
Van der Salm showed that stimulating the spastic muscle itself was most effective in relaxing spasms, probably because the stimulation fatigues the muscle and improves blood circulation to the muscle.
The takeaway here is that electrically stimulating a muscle can prevent spasms for several hours afterward, so it can be used as needed to manage spasticity.
Final thoughts
There are many different factors to consider when choosing how to manage spasticity. The cause of spasticity, your situation and medical condition, and other factors like financing and support can all affect your decision.
At the end of the day, a combination of methods will probably be best. For example, many people are fine with a low dose of medications combined with regular stretching and strengthening. It’s always best to consult your physician to find out what approach will be best for you.
For more information about muscle spasticity, check out the resources below.
MYOLYN and the MyoCycle
If you know someone who could use some help in managing spasticity, please share this article with them using the social media links at the top of the post.
The MyoCycle combines electrical stimulation with range of motion and strengthening exercise and is cleared by the FDA for general rehab for:
- Relaxation of muscle spasms
- Prevention or retardation of disuse atrophy
- Increasing local blood circulation
- Maintaining or increasing range of motion
To learn more about managing spasticity with the MyoCycle, reach out to us today!
Resources
Cleveland Clinic: Spasticity
National MS Society: Spasticity
MedlinePlus: Caring for muscle spasticity or spasms
UAB-SCIMS: Spastic Hypertonia Spasticity following SCI
