October 6th is World Cerebral Palsy Day! Cerebral palsy is the most common motor disability in childhood. Though we know that genetics can play a role in the development of this disorder, not much is known about the actual genetic changes that can cause cerebral palsy. Let's learn more.
What is cerebral palsy?
Cerebral palsy (CP) is a term to describe disorders that affect movement, balance, posture, and muscle tone.1 CP is caused by damage to the brain or abnormal development of the brain, which can happen before, during, or after birth. Not only is CP the most common motor disability in childhood, but also the most common cause for childhood mortality.2 Most (85%-90%) cases of CP are congenital, which means that the damage happens pre or during birth. Acquired CP is when brain damage occurs more than 28 days after birth.
There are several types of cerebral palsy; some people have symptoms of multiple types of CP1:
This is the most common type of CP, affecting around 80% of those with CP. Those with spastic CP have stiff muscles caused by hypertonia, or increased muscle tone. This can lead to difficulty walking, exaggerated reflexes, muscle weakness, and paralysis. Spastic CP can manifest in several ways, such as affecting only the legs (spastic diplegia), affecting just one side of the body (spastic hemiplegia), or affecting all limbs, trunk, and face (spastic quadriplegia). Spastic quadriplegia is the most severe and often causes seizures, intellectual disability, and sensory problems. Spastic CP is caused by damage or developmental differences in the cerebral cortex.
This type of CP causes involuntary movements in the limbs and hands. Occasionally, the face is also affected. Not only do the type and speed of movements vary from person to person, but the individual’s muscle tone can also vary from day to day. Dyskinetic CP is caused by damage or developmental differences in the basal ganglia.
People with Hypotonic CP have hypotonia, or low muscle tone. This can cause problems in newborns as they sometimes struggle to breath. Adults may have problems speaking, walking, and even sitting. Hypotonic CP is caused by damage or developmental differences in the cerebellum.
The least common form of CP causes voluntary movements to appear jerky. This often causes problems with coordination, balance, walking, and other fine motor functions. Ataxic is caused by damage or developmental differences in the cerebellum.
Cerebral palsy is caused by damage to different areas of the brain3:
Individuals with cerebral palsy are more likely to have a pathogenic variant in their DNA
Although CP is diagnosed using neuroimaging techniques,5 genetic testing can be an important tool in helping care for those with CP. Several studies have shown that chromosomal microarray, a type of genetic test that looks for duplications or deletions in genes, can be helpful for individuals with CP. One study examined a cohort of patients with CP who participated in chromosomal microarray genetic testing and found that 9.5% of them had a pathogenic variant in their DNA.6
A pathogenic variant is a change in DNA that increases the likelihood for having a certain disease or disorder. Knowing that these individuals had a pathogenic variant led to changes in their medical care, keeping them healthier and giving them better resources to succeed. Several other genetic testing studies showed similar rates of pathogenic variants in individuals with CP who had genetic testing. Another study found that adults with CP had a 75% increased risk of acquiring a noncommunicable disease, specifically for respiratory and cardiovascular disease, again displaying the importance of screening for other diseases in individuals with CP.7 It is vital to be aware of these facts and monitor those with CP to avoid preventable problems in the future.
What increases the risk of cerebral palsy?
First, it is important to understand the concept of risk factors, which are events, substances, or circumstances that increase the risk of developing a disease. Risk factors do not guarantee that an individual will develop a disease; conversely, the absence of risk factors does not mean that an individual will not develop the disease.4 There are different risk factors for congenital and acquired CP.1Congenital CP Risk Factors:
Infection (especially brain infections like meningitis or encephalitis)
Not enough blood flow to the brain
It’s also important to remember that often CP is caused for an unknown reason, which means that it is difficult to prevent. For example, very little is known about genetic changes that can contribute to developing CP and are not preventable.2
What can I do for my child with cerebral palsy?
Though there are no treatments that will eliminate CP, there are things you can do to treat and manage CP, giving those with the disease a better quality of life. Some of these things include:5
Speech and language therapy
Injections for muscles or nerves
Oral muscle relaxants
CP is a term that describes a group of disorders and is the most common motor disability in childhood
CP can be caused before or during birth (congenital CP) and after birth (acquired CP)
There are many different types of CP, or ways that it manifests in individuals
Though CP is diagnosed by neuroimaging, genetic testing can be critical for individuals with CP to ensure there are no co-existing conditions that need medical attention
Centers for Disease Control and Prevention: Cerebral Palsy (https://www.cdc.gov/ncbddd/cp/facts.html)
Y. Zhang, et al. 2019. PMID: 31551709
Cerebral Palsy Guide: Types of Cerebral Palsy (https://www.cerebralpalsyguide.com/cerebral-palsy/types/)
CerebralPalsy.org: Prevention of Cerebral Palsy (https://www.cerebralpalsy.org/about-cerebral-palsy/prevention)
Mayo Clinic: Cerebral Palsy (https://www.mayoclinic.org/diseases-conditions/cerebral-palsy/symptoms-causes/syc-20353999)
R. Vanzo, et al. 2017. AAN poster presentation, Boston MA: https://issuu.com/americanacademyofneurology/docs/17am_scienceprogramdigi_v716