Posted by: Thixia | October 21, 2008

Spasticity in MS 2 of 9

What is spasticity and what causes it?





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 hyper-reflexia, 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. 



An interdisciplinary team can better identify goals and make the adjustments necessary to attain optimal spasticity management



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 and the range of motion in joints
  • ­      negative impact on endurance and energy expenditure l interference with the activities of daily living
  • ­      discomfort or pain l 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. 






Compliments of:


Multiple Sclerosis International

Federation (MSIF)


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