What Causes Cerebral Palsy?

Cerebral palsy is caused by abnormal development or damage to parts of the brain. Damage can occur before, during, or shortly after birth. Children with congenital cerebral palsy may not be detected until months or years later. Any interruption in brain growth during fetal development can cause brain malformations.

Acquired cerebral palsy is less common and may be caused by a head injury, or brain infections such as bacterial meningitis or viral encephalitis. Factors that may lead to problems with brain development include:

• Blood Incompatibility:  between a mother and child, or Rh incompatibility, develops when a mother’s Rh blood type (positive or negative) is different from the blood type of her child. The mother’s system doesn’t tolerate the baby’s different blood type and the body will begin to make antibodies that will attack and kill a baby’s blood cells.
• Maternal infections that affect a developing fetus: Infections like toxoplasmosis, rubella, cytomegalovirus, and herpes can infect the womb and fetus. Inflammation triggered by an infection may damage the nervous system in an unborn baby. Maternal fever during pregnancy or delivery may also lead to an inflammatory response.
• Fetal stroke: a disruption of blood supply to the developing brain. Bleeding in the brain, or intracranial hemorrhage, may be caused by weak blood vessels or by blood-clotting abnormalities. High Maternal blood pressure (hypertension) is more common in babies with fetal stroke. Maternal infection, especially pelvic inflammatory disease, may increase the risk of fetal stroke.
• Infant infections that cause inflammation in or around the brain
• Traumatic head injury to an infant during or soon after birth
• Toxic Exposure during pregnancy can harm the fetus. There are several cases of pharmaceutical injury linked to drugs that may harm a baby.
• Lack of oxygen to the brain (asphyxia) related to a complicated labor or delivery. If the oxygen supply is cut off or reduced, an infant can develop brain damage which destroys tissue in the cerebral motor cortex and other areas of the brain. This kind of damage can be due to maternal low blood pressure, rupture of the uterus, detachment of the placenta, problems involving the umbilical cord, or delivery trauma.
• Breech presentation—infants with cerebral palsy are more likely to be in a breech position (feet first) instead of head first on the onset of labor. Complicated labor and delivery can lead to child vascular or respiratory problems, and cause brain damage.
• Jaundice: more than 50 percent of newborns develop jaundice after birth when bilirubin builds up faster than their livers can break it down. Untreated jaundice can cause brain damage, deafness and CP.

Birth Injury Risk Factors

A number of factors are associated with an increased risk of cerebral palsy. Some factors are genetic, though others are preventable. According to the U.S. Centers for Disease Control and Prevention (CDC), the leading preventable risk factors are disruption of the oxygen supply during birth (birth hypoxia), which may account for up to 10 percent of CP cases, and infection among mothers.

Infection of the placental membranes (chorioamnionitis) is associated with an increased risk of CP for children born full-term. Chorioamnionitis has been found to account for 12 percent of CP cases among children born full-term and 28 percent of CP cases among children born prematurely.

Having the proper vaccinations are critical for reducing the risk of some diseases that affect the development of a child. Physicians should make sure mothers are vaccinated. Certain maternal infections can significantly increase cerebral palsy risk to the baby, including the following:

• German measles (rubella)
• Chickenpox (varicella)
• Cytomegalovirus
• Herpes
• Toxoplasmosis
• Syphilis
• Zika Virus
• Other high risk factors include the following:
• Infant illness—bacterial meningitis, viral encephalitis, untreated jaundice
• Complicated births—breech births, low birth weight, premature births

Early Signs of Cerebral Palsy

The first signs of cerebral palsy usually appear in the early months after birth. Infants will frequently have a delay in development, and may be slow to learn to roll over, sit, crawl, and walk. Some infants have abnormal or undeveloped muscle tone.

A decreased muscle tone, or hypotonia, can make babies appear relaxed, while an increased muscle tone, or hypertonia, may make them look stiff or rigid. Children with CP can be seen with an unusual posture and favor one side of the body. Some warning signs include:

• Head lags when picked up
• Child feels stiff or floppy
• Child doesn’t roll over
• Baby has no hand dexterity
• Infant crawls in an off-kilter manner

Cerebral Palsy Symptoms

Signs and symptoms of CP can vary greatly, and generally appear during infancy or preschool years. The disability associated with cerebral palsy may affect one limb or one side of the body, or the whole body. The brain disorder causing cerebral palsy doesn’t change with time, so the symptoms usually don’t worsen with age. Movement and coordination problems associated with cerebral palsy may include:

• Variations in muscle tone
• Stiff muscles
• Exaggerated reflexes (spasticity)
• Lack of muscle coordination
• Involuntary movements
• Delays in reaching motor skill milestones
• Favoring one side of the body
• Difficulty walking
• Excessive drooling—problems with swallowing
• Difficulty eating
• Delays in speech development
  Brain abnormalities associated with cerebral palsy also may contribute to other neurological problems, including the following:
• Difficulty with hearing and vision
• Intellectual disabilities
• Seizures
• Abnormal touch or pain perceptions
• Mental health conditions
• Urinary incontinence

Types of Cerebral Palsy

The specific kind of cerebral palsy will be determined by the extent, type, and location of a child’s brain abnormalities. Doctors often classify CP according to movement disorders involved, including:

• Spastic Cerebral Palsy—the most common type of the disorder. Characterized by stiff muscles and awkward movements. Spastic hemiplegia usually affects the arm or hand on one side of the body. Children with spastic hemiplegia generally walk later and on the tips of their toes because of tight heel tendons. The arm or leg on the affected side are frequently shorter and thinner. Some children will develop scoliosis. Spastic hemiplegia may also cause seizures and speech impairments.
• Spastic diplegia involves muscle stiffness, typically in the legs. Reflexes in the legs are hyperactive. Children may require a walker or leg braces. Intelligence and language skills are usually unaffected.
• Spastic quadriplegia is the most severe form of cerebral palsy and is associated with intellectual disability. It is caused by brain damage or brain malformations. Children will often have severe stiffness in their limbs and trouble walking.
• Dyskinetic cerebral palsy (athetoid, choreoathetoid, and dystonic cerebral palsies) is characterized by slow and uncontrollable movements of the limbs. Hyperactivity in the muscles of the face and tongue, difficulty walking, problems talking and hearing are also signs.
• Ataxic cerebral palsy affects balance and depth perception, leading to poor coordination and walking issues. There may be difficulty with certain movements like writing or buttoning a shirt.

Muscle weakness and coordination problems can contribute to a number of complications either during childhood or later in life. Developing health issues may include the following:

• Eye muscle imbalance—may affect visual fixation and tracking.
• Lung disease and breathing disorders
• Neurological conditions—people with cerebral palsy are likely to develop movement disorders or worsened neurological symptoms over time.
• Osteoarthritis—muscle spasticity may lead to the early onset of painful degenerative bone diseases
• Mental health conditions—the challenges of coping with disabilities may contribute to depression.
• Epilepsy