Pathophysiology and primary causes of spasticity

Spasticity is one of the Features of Upper Motor Neuron Syndrome

Upper motor neuron syndrome is caused by damage to one (or more) area(s) of the central nervous system involved in controlling voluntary movement. Upper motor neuron syndrome can be divided into two broad groups of phenomena:

  • Negative: refer to what is lost, such as motor skills, strength and motor control
  • Positive: characterized by an abundance of muscle hyperactivity, such as:
    • Spasticity
    • Hypereflexia: increased stretch reflexes
    • Clonus: uncontrollable movement of a body limb, especially the ankle
    • Co-contractions: involuntary contractions of a limb or a part of the limb while the individual is actively moving another part, e.g., adduction of the shoulder while walking
    • Muscles spasms

Some of the symptoms of upper motor neuron syndrome are easily confused with spasticity. It is not unusual to see patients who show other upper motor neuron findings diagnosed with spasticity. The damage to the central nervous system underlying upper motor neuron syndrome is often associated with one of the following diseases:

  • Stroke
  • Multiple sclerosis
  • Cerebral palsy
  • Traumatic brain and/or spinal cord injury
  • Brain tumor
  • Brain damage caused by:
    • Oxygen deficiency
    • Encephalitis: infection of the brain
    • Meningitis: infection of the covering of the brain and spinal cord

The severity of the resulting muscle spasticity partly depends on the site of the upper motor neuron lesion.

Multiple sclerosis is an autoimmune disease in which the immune system attacks myelin, the fatty protective sheath that surrounds the neurons of the central nervous system (similar to the isolation around an electric cable), by secreting toxins that cause inflammation and swelling of the myelin sheath. The inflammation blocks the passage of messages along the neuron. The immune system also breaks down the myelin in a process known as demyelination. This destructive process causes the electrical communication between neurons to become distorted, slowed down or lost, resulting in multiple sclerosis symptoms.

Evolution from multiple sclerosis varies from one patient to another and also within the same patient. Patients have relapses of the disease followed by remission. After a certain number of relapses, symptoms may remain permanent. Multiple sclerosis can affect any part of the central nervous system, e.g., the brain, the cerebellum or the spinal cord. If the disorder affects the motor areas in the central nervous system, the connections between the brain and the muscles are disturbed, which can lead to spasticity. Other frequent symptoms are:

  • Balance impairment
  • Coordination difficulties
  • Bladder dysfunction
  • Visual impairment

Traumatic brain injury causes substantial disability and mortality, especially among young adults. It occurs when a sudden trauma damages the brain and disrupts normal brain function. The main causes of traumatic brain injury are falls, vehicle accidents and violence.

Traumatic brain injury may have profound physical, psychological, cognitive, emotional and social effects. The risk of death at the early phase is quite high in the severe cases. Upper motor neuron syndrome is a common complication in the moderate or severe cases. In that population, the prevalence of epileptic seizures and cognitive decline is very high.

Although well-protected by the vertebrae of the spinal column, the spinal cord can be damaged in many ways. Most spinal cord injuries occur as a result of motor vehicle accidents, sports injuries, violence or falls (predominantly in elderly persons).

The symptoms of spinal cord injury depends on the point on the cord where damage occurs and whether or not severance of the cord is complete or partial. In incomplete injuries, patients have some remaining function of their bodies below the level of injury, while in complete injuries they have no function below the level of injury.

Injuries to the spinal cord can cause loss of:

  • Muscle function
  • Sensation in the body below the level of injury
  • Control of the bowels and bladder
  • Normal sexual function

Spinal cord injuries in the upper neck can cause difficulty breathing and may require the use of a breathing machine or ventilator.

Cerebral palsy is caused by damage to the motor control centers of the developing brain and can occur during pregnancy, during childbirth, or after birth up to about an age of three. The damage to the motor control center can have various reasons such as:

  • Accident during pregnancy
  • Drug abuse of the pregnant mother
  • Infections
  • Birth malformation
  • Abnormal brain development
  • Arterial malformation

Cerebral palsy causes physical impairment as seen in the upper motor neuron syndrome. Balance, posture and coordination can also be affected. Others quite common complications are cognitive impairment, epileptic seizures and vision or hearing impairment.

Every case of cerebral palsy is unique with a very broad range of disabilities and symptoms.


A stroke occurs when blood supply to a part of the brain is interrupted or severely reduced. If blood flow is cut off for longer than a few seconds, the brain does not receive enough blood and oxygen to fulfill its functions. Consequently, nerve cells die, causing lasting damage.

There are two major types of stroke:

  • Ischemic: an ischemic stroke occurs when a cerebral artery is blocked by a blood clot, which has developed either at the site of blockade (atherosclerosis) or in other parts of the body (arterial embolism)
  • Hemorrhagic: a hemorrhagic stroke is caused by weak blood vessels that burst open. The escaping blood accumulates and compresses the surrounding nerve cells

Depending on the brain region affected, a stroke might lead to a vast variety of symptoms such as:

  • Inability to move the upper and/or lower limb on one side of the body (hemiplegia)
  • Incapability to understand or formulate speech (aphasia)
  • Visual disturbances

Symptoms can be:

  • Transient with a transient ischemic attack lasting between few seconds and hours. It is an alert that should lead to an immediate consultation
  • Permanent: those symptoms usually improve over time, especially when an appropriate rehabilitation program is set

About 38% of stroke survivors develop post-stroke spasticity. 1


How Karl’s life is influenced by spasticity



In everyday life, patients with spasticity may experience physical symptoms (e.g., pain, contractures, pressure sores), decreased functional abilities, difficulties with mobility, hygiene and care, decreased quality of life, and be prone to developing secondary conditions such as infections and psychological disorders, especially anxiety and depression.

Your questions around spasticity



Here you will find the most frequently asked questions (FAQs). We will be updating this section periodically.

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