The type of movement issues seen in a person with CP depends on how severely a brain injury has impacted muscle tone. Muscle tone is defined as the strength and tension of the muscles.
There are two common terms used to describe how cerebral palsy affects muscle tone — hypotonia and hypertonia. These are useful to better understand the types of CP.
- Hypotonia – Low muscle tone, causing a loss of strength and firmness
- Hypertonia – High muscle tone, causing rigidity and spasmodic movement
Different Types of Cerebral Palsy
Spastic Cerebral Palsy
Spastic cerebral palsy is the most common type of CP, making up 70 to 80 percent of cases. People with spastic cerebral palsy often experience exaggerated or jerky movements (hypertonia).
Spastic CP is caused by damage to the brain’s motor cortex, which controls voluntary movement. It is also caused by damage to the pyramidal tracts, which help relay signals to the muscles. This is why spastic CP is sometimes referred to as “pyramidal”.
The motor cortex is found on both sides of the brain and the pyramidal tracts connect each side of the motor cortex. Damage to the right side of the motor cortex causes movement problems on the left side of the body, and vice versa.
Common signs and symptoms of spastic cerebral palsy include:
- Awkward reflexes
- Stiffness in one part of the body
- Contractures (permanently tightened muscles or joints)
- Abnormal gait
Athetoid Cerebral Palsy
About 10 percent of children with cerebral palsy are diagnosed with athetoid CP, or “non-spastic CP”. This type of CP is characterized by a mixture of hypotonia and hypertonia, which causes muscle tone to fluctuate. The main trait of athetoid cerebral palsy is involuntary movement in the face, torso and limbs.
This type of cerebral palsy is caused by damage to the brain’s basal ganglia and/or cerebellum. The basal ganglia is responsible for regulating voluntary motor function and eye movements, while the cerebellum controls balance and coordination.
Athetoid CP is referred to as “extrapyramidal” because the extrapyramidal tracts in the brain help regulate involuntary reflexes and movement signaled by the basal ganglia and cerebellum.
Common symptoms associated with athetoid cerebral palsy include:
- Stiff or rigid body
- Floppiness in the limbs
- Problems with posture
- Issues feeding
Ataxic Cerebral Palsy
Ataxia is a type of CP that causes problems with balance and coordination. Ataxic cerebral palsy makes up a small percentage of all cases. Those with ataxic CP typically have issues surrounding voluntary movement.
Ataxic cerebral palsy is different than other types of CP because it is primarily caused by damage to the cerebellum, which controls balance and coordination. People with ataxic CP often experience tremors and a reduction in muscle tone.
Common symptoms of ataxic cerebral palsy include:
- Difficulty speaking
- Problems with depth perception
- Shakiness and tremors
- Spreading feet apart when walking
Mixed Cerebral Palsy
Sometimes damage to the developing brain isn’t confined to one location. In these circumstances, it is possible for a child to develop cerebral palsy that is characteristic of multiple brain injuries.
When a child is showcasing symptoms of more than one type of CP, it is considered to be mixed cerebral palsy. This diagnosis makes up less than 10% of all CP cases.
The most common mixed cerebral palsy diagnosis is a combination of spastic and athetoid CP. Parents and caregivers should seek out CP specialists if they suspect more than one type of cerebral palsy is present.
Location of Movement Problems
The type of cerebral palsy explained by the location of movement problems is more straightforward than the classification by brain injury. The location of movement problems, however, is related to the location of the brain injury.
Damage to the right side of the motor cortex causes issues with motor functions on the left side of the body — an issue that defines the location of movement issues. Yet, there is a range of different areas where normal motor skills may be affected.
Only one limb’s movement is affected. It usually occurs in the arm or leg. This type of movement problem is very rare.
Two limbs, usually the legs, are affected. Oftentimes, those with diplegia have mild movement problems in the upper body as well. In those with cerebral palsy, diplegia is commonly the result of premature birth.
One side of the body is affected. The arm is usually more impacted than other limbs, distinguished by a rigidly flexed wrist or elbow. Some people with hemiplegia may not be able to use the affected hand. Prenatal bleeding in the brain can cause hemiplegia.
Three limbs are affected.
All four limbs are involved, but the legs are affected worse than the arms. There may be limited control over facial muscles as well.
Like quadriplegia, all four limbs are affected, but the arms are more affected than the legs.
Determining The Type of CP
When a child is diagnosed with cerebral palsy, their diagnosis encompasses the brain injury and movement problem. For example, a diagnosis of cerebral palsy may be “spastic diplegia” or “athetoid quadriplegia”.
To learn more about the various types of cerebral palsy and how to get an accurate diagnosis, download our free Cerebral Palsy Guide. You will find over 60 pages of in-depth information for children and parents of a child with CP.