Introduction
Spasticity is commonly experienced by individuals who have damage to their central nervous system such as spinal cord injury, stroke, closed head injury, cerebral palsy and MS. In a 2001 survey of the North American Research Consortium on MS (NARCOMS) registry, approximately 85 percent of people with MS reported experiencing some spasticity. Spasticity is generally defined as being “velocity dependent”, which means that when a quick stretch is applied to a muscle, the resistance is increased.
What it generally means for people with MS-related spasticity is that they have an increased stiffness or tightness in their muscles, which often adversely affects movement. They may or may not experience other components of abnormal muscle tone, such as spasms.
The biggest challenge with spasticity management is determining what the optimal level of muscle tone is for an individual. In some cases an increased muscle tone may assist with movement, but more commonly it negatively affects an individual’s normal movement.
A look at the inner mechanics
In MS, spasticity is due to nerve conduction being interrupted by a lesion located in the brain or spinal cord. It can be present at any point of the disease (early or late onset) and the symptoms can vary from mild to severe.
Spasticity occurs as a result of an imbalance between the excitatory and inhibitory signals from the brain and/or spinal cord. Excitatory signals send messages to other neurons, firing them into action, whereas inhibitory signals stop neurons firing and suppress a response, such as stopping a full bladder from spontaneously emptying itself. The primary theory is that there is an interruption of the inhibitory signals along the spinal cord and in the brain which results in an increased excitation and therefore an imbalance.
The nerve pathway connecting the brain and spinal cord is made of upper motor neurones. The pathway between the spinal cord and muscles is made of lower motor neurones. Spasticity is a consequence of an “upper motor neuron (UMN) syndrome”. The interruption of signals caused by MS lesions means that the upper motor neurones can no longer regulate messages to the lower motor neurones. The lower motor neurones can then become overactive and hypersensitive, causing stiffness or spasms in the muscles.
Other common symptoms seen with UMN syndromes include increased deep tendon reflexes or hyperreflexia, such as overactive or over-responsive reflexes, decreased strength, coordination and motor control, and even the appearance of primitive reflexes, which are reflex actions commonly seen in infants (such as the sucking reflex, where babies suck anything that touches their mouth) but which do not usually continue into adulthood.
In addition to spasticity, it is important to consider other aspects of abnormal muscle tone. This may include movement disorders such as dystonia, which creates involuntary muscle contractions causing twisting or repetitive movements, or forces the body into unusual postures. It may also include “non-neural” components such as changes in muscle or connective tissue. An example would be a contracture, such as muscle or connective tissue shortening, which then alters the muscle’s ability to stretch. It is important to determine all aspects of abnormal muscle tone when developing a treatment plan, since the cause will help guide the
treatment.
The messages that control our muscles.
What spasticity does
Spasticity affects body functions as identified
by the International Classification of Function. It
can cause activity limitations and participation
restrictions, primarily due to its effect on functional
movement.
Some of the detrimental consequences associated
with spasticity include:- interference with mobility, ability to exercise andthe range of motion in joints
- negative impact on endurance and energy expenditure
- interference with the activities of daily living
- discomfort or pain
- sleep disturbance
- increased difficulty for caregivers (for example with transfers or hygiene).
These factors can contribute to a decreased independence, a decreased quality of life and may impact on a person’s role within the family, such as being a parent. Spasticity can fluctuate due to outside influences.
For example, hot temperatures may cause a decrease in spasticity for people with MS while infections and exacerbations may cause a significant increase in spasticity. It is important that a person receives treatment if there are drastic changes in spasticity, but the cause of the change must first be determined. If it is due to an infection, it is crucial that the infection be treated first. The same is true of skin breakdown or an MS exacerbation. Any residual increases after treating the “cause” should then be addressed through additional assessment and management of the
spasticity.
Spasticity can interfere with gardening, exercising and performing activities of daily living.
Managing spasticity
It is particularly important to approach spasticity management from an interdisciplinary team approach (neurologist, nurse, rehabilitation physician and other rehabilitation specialists), including the person with spasticity and their caregiver. An interdisciplinary team can better identify goals and make the adjustments necessary to attain optimal spasticity management.
Goals of spasticity management should be orientated towards the improvement of function and improved comfort, and an individual’s response to interventions such as medications, rehabilitation or surgery should be closely monitored. With close monitoring and the involvement of an interdisciplinary team, adjustments can be made according to changes in spasticity and function. Medications can be increased or decreased, appropriate adaptive equipment can be recommended and training provided, and other interventions can be explored.
When treating spasticity it is important to focus goals on management and not necessarily on the elimination of the spasticity since some individuals use their spasticity to assist with functional movements. In addition, for individuals who have restricted movement, spasticity may help promote circulation by maintaining muscle contractions which can promote the return of blood to the heart.
Conclusion
People with MS may experience many different symptoms during the course of the disease, and spasticity is one of the most common. However, spasticity is often a treatable symptom and can be managed to decrease its adverse effects on overall function. Utilising a team approach can be very effective for proper identification, goal-setting and appropriate interventions.
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