Causes and Risk Factors of Cerebral Palsy

cerebral palsy causes and risk factors
© Verywell, 2018 

Cerebral palsy is defined as a congenital (present at birth or shortly after birth) deficit of motor or cognitive skills caused by either damage to the brain or intrinsic developmental problems of the brain that occurred during a mother’s pregnancy or shortly after the birth of her baby. Cerebral palsy is a term that means motor weakness of cerebral (brain) etiology.

 

Affecting about 1 out of 500 children and adults, there are some known causes and risk factors for this condition.

Common Causes 

It is important to note that most of the recognized causes of cerebral palsy can occur without the subsequent development of this condition. It is not completely clear why some children who experience these events develop cerebral palsy and some do not. 

Idiopathic 

In many situations, there is no identified cause of cerebral palsy. While there are a number of known causes of cerebral palsy, if your or your child has been diagnosed your medical team may not be able to identify a cause.

The majority of children who are diagnosed with this condition were not known to be exposed to the recognized causes or risk factors, have normal brain imaging tests and do not have genetic abnormalities associated with cerebral palsy. 

Developmental Cerebral Abnormalities

Sometimes, the imaging tests of a child or an adult with cerebral palsy may show patterns of malformation in the anatomical structure of the brain.

Some areas of the brain may be larger or smaller than average or of an unusual contour. Larger than usual spaces filled with fluid may be present in some instances.

Sometimes, imaging studies may reveal brain structure that is not necessarily altered in size or shape, such as in focal cortical dysplasia, a condition where the neurons in an area of the brain do not migrate to their proper location.

The cause of developmental cerebral abnormalities is not usually identified. 

Hypoxia 

When a developing unborn baby or a newborn baby suffers from a lack of oxygen, even for a brief period of time, this can cause permanent damage to the growing baby’s brain. Hypoxia can occur due to a variety of situations such as maternal trauma, severe maternal illness, and crises during labor and delivery or from unknown causes. 

Infections 

Some maternal infections can impact the developing baby’s brain, causing cerebral abnormalities that manifest as cerebral palsy, particularly if they advance to cause severe systemic infections such as sepsis. 

Trauma 

Maternal trauma can affect the baby’s brain in a number of ways, potentially leading to cerebral palsy. Material blood loss or oxygen deprivation experienced as a result of trauma can cause the developing baby to suffer from hypoxia. The physical effects of traumatic impact may also harm the baby in ways that lead to or contribute to cerebral palsy.

Cerebrovascular Disease

A developing baby or a newborn baby can have a stroke, resulting in permanent motor or cognitive deficits characteristic of cerebral palsy. The cause of the stroke may be unknown, or it may be related to maternal illness or blood clotting conditions.

Low Birth Weight

Low birth weight has been associated with cerebral palsy. Specifically, babies who weigh less than 4 pounds at birth are at a higher risk of cerebral palsy than babies who weigh more.

Prematurity

Babies who are born at 28 weeks gestation—which is 12 weeks short of full term (40 weeks) are at higher risk of cerebral palsy than babies who are not premature.

Labor and Delivery Crisis

Emergency situations during labor and delivery can cause severe physical stress for the baby and may also produce several of the causes of cerebral palsy, such as cerebrovascular events and hypoxia.

Nutritional 

Some nutritional deficits may cause cerebral palsy. Extreme vitamin and mineral shortages, such as folic acid deficiency, can cause serious harm to the baby’s developing brain. Extreme calorie deficits caused by maternal illness, food scarcity or any other cause of starvation, can also contribute to the development of cerebral palsy. 

Severe Maternal Illness  

The vast majority of pregnant women who experience illness during pregnancy have healthy children. Yet illnesses such as severe blood pressure alterations, stroke, liver disease, kidney disease or heart disease can cause disruption in the delivery of blood, nutrients, and oxygen to the developing baby.

Some illnesses can cause material such as bilirubin, ammonia or other toxins to deposit or build up in the growing baby’s body, causing damage to the baby’s growing brain.

Genetics 

The role of genetics in cerebral palsy is not completely clear. Generally, it has been thought that heredity may only be responsible for a small percentage of cases. However, recent research suggests that genetic abnormalities may be a source of more cases of cerebral palsy then previously thought. 

The hereditary pattern of cerebral palsy is believed to be autosomal recessive, which means that in order for the condition to be manifest, the child who inherits the hereditary forms of cerebral palsy had to inherit defective genes from both parents, who do not necessarily have symptoms of the condition themselves.

Some genetic abnormalities are hereditary, while some are de novo—meaning that they are new genetic abnormalities arising in either the child who has cerebral palsy or in one of the child’s parents without having been present in the family before.

Some genetic patterns associated with cerebral palsy, particularly with de novo genetic alterations, involve genomic copy number variations. These are sections of genes that are irregularly and mistakenly repeated on a chromosome, causing the development of the disease. So far, no single gene has been identified as the gene responsible for cerebral palsy, and researchers have found several genetic abnormalities that could each independently cause the condition.

Lifestyle Risk factors

There are a few lifestyle risk factors associated with cerebral palsy, and these are generally risk factors that relate to the mother’s pregnancy or to the time of labor and delivery. 

Maternal Drug Use

Drug use during any stage of pregnancy may contribute to cerebral palsy. Some drugs such as cocaine and methamphetamine can affect the blood flow and heart function of both a mother and her developing baby in ways that increase the risk of cerebrovascular disease in the unborn infant or during labor and delivery. Drug use also increases the likelihood of a medical crisis during labor and delivery.

Ingested Toxins 

Some strong medications are not approved for use during pregnancy, as they may increase the risk of a variety of negative consequences for the baby, including cerebral palsy. 

Environmental Toxins

Substances in the environment, such as cat litter, mercury, lead, other contaminants and industrial chemicals, can be ingested or inhaled by a pregnant woman and may reach her developing baby’s body, causing congenital problems such as cerebral palsy.

Sources:

Maclennan AH, Thompson SC, Gecz J. Cerebral palsy: causes, pathways, and the role of genetic variants. Am J Obstet Gynecol. 2015;213(6):779-88.

Zarrei M, Fehlings DL, Mawjee K, et al. De novo and rare inherited copy-number variations in the hemiplegic form of cerebral palsy. Genet Med. 2018;20(2):172-180.