Cerebral Palsy – Pathophysiology, Symptoms, and Prevention

What is Cerebral Palsy?

Cerebral palsy (CP) is a group of disorders that affect a person’s ability to move and maintain balance and posture. CP is the most common motor disability in childhood. Cerebral means having to do with the brain. Palsy means weakness or problems with using the muscles. CP is caused by abnormal brain development or damage to the developing brain that affects a person’s ability to control his or her muscles.

The symptoms of CP vary from person to person. A person with severe CP might need to use special equipment to be able to walk, or might not be able to walk at all and might need lifelong care. A person with mild CP, on the other hand, might walk a little awkwardly, but might not need any special help. CP does not get worse over time, though the exact symptoms can change over a person’s lifetime.

All people with CP have problems with movement and posture. Many also have related conditions such as intellectual disability pdf icon; seizures; problems with vision pdf icon, hearing, or speech; changes in the spine (such as scoliosis); or joint problems (such as contractures).

Types of Cerebral Palsy

Doctors classify CP according to the main type of movement disorder involved. Depending on which areas of the brain are affected, one or more of the following movement disorders can occur:

• Stiff muscles (spasticity)
• Uncontrollable movements (dyskinesia)
• Poor balance and coordination (ataxia)

There are four main types of CP:

Spastic Cerebral Palsy

The most common type of CP is spastic CP. Spastic CP affects about 80% of people with CP. People with spastic CP have increased muscle tone. This means their muscles are stiff and, as a result, their movements can be awkward. Spastic CP usually is described by what parts of the body are affected:

• Spastic diplegia/diparesis – In this type of CP, muscle stiffness is mainly in the legs, with the arms less affected or not affected at all. People with spastic diplegia might have difficulty walking because tight hip and leg muscles cause their legs to pull together, turn inward, and cross at the knees (also known as scissoring).
• Spastic hemiplegia/hemiparesis – This type of CP affects only one side of a person’s body; usually the arm is more affected than the leg.
• Spastic quadriplegia/quadriparesis – Spastic quadriplegia is the most severe form of spastic CP and affects all four limbs, the trunk, and the face. People with spastic quadriparesis usually cannot walk and often have other developmental disabilities such as intellectual disability; seizures; or problems with vision, hearing, or speech.

Dyskinetic Cerebral Palsy

This type also includes athetoid, choreoathetoid, and dystonic cerebral palsies)

People with dyskinetic CP have problems controlling the movement of their hands, arms, feet, and legs, making it difficult to sit and walk. The movements are uncontrollable and can be slow and writhing or rapid and jerky. Sometimes the face and tongue are affected and the person has a hard time sucking, swallowing, and talking. A person with dyskinetic CP has muscle tone that can change (varying from too tight to too loose) not only from day to day but even during a single day.

Ataxic Cerebral Palsy

People with ataxic CP have problems with balance and coordination. They might be unsteady when they walk. They might have a hard time with quick movements or movements that need a lot of control, like writing. They might have a hard time controlling their hands or arms when they reach for something.

Mixed Cerebral Palsy

Some people have symptoms of more than one type of CP. The most common type of mixed CP is spastic-dyskinetic CP.

What Causes Cerebral Palsy (CP)?

Cerebral palsy is a neuromuscular disorder caused by damage to the motor cortex of the developing brain. This affects motor functioning, including an individual’s ability to move, grasp objects and talk.

It can also affect muscle tone, resulting in individuals with overly toned, tight muscles and rigid joints or loose, floppy muscles and joints.

The type and severity of CP symptoms will depend in large part on the extent of the brain injury and when it occurred. There are four primary situations that will lead to cerebral palsy to arise:

• Prenatal disturbance of brain cell migration. In the developing fetus, cells differentiate and move into place in order to form the appropriate type of cell. If something disrupts this process, preventing brain cells from migrating and developing properly, a number of neurological conditions can arise.
• Prenatal poor myelination of nerve cells. In the body, myelin acts as insulation to protect nerve cells. Inadequate myelin can result in unprotected nerve cells, which can become damaged.
• Perinatal brain cell death. During the birthing process, brain cells may die as a result of asphyxia (suffocation) or blood loss. This is most commonly seen in difficult deliveries or periods of fetal distress late in pregnancy necessitating an emergency birth.
• Postnatal non-functional or inappropriate synapses. After birth, brain injury can result in brain damage and CP. Some common causes are brain infection, trauma, and asphyxia.

Although not every case of CP is preventable, and the underlying causes of many CP cases are unknown, there are certain risk factors that can increase a child’s odds of developing cerebral palsy:

• Premature birth or low birth weight
• Fetal distress, including problems with the placenta, umbilical cord, and amniotic fluid
• Long and difficult labor during which asphyxiation can occur
• Meningitis or other brain infection
• Trauma after birth, including accidents that could lead to brain damage

Although the exact cause of an individual’s cerebral palsy is not always uncovered, it’s estimated that between 10 to 15 percent of CP cases arise as a result of medical malpractice. This may include:

• Failure to recognize fetal distress during labor and intervene accordingly
• Failure to resuscitate a “blue baby” quickly enough after birth
• Writing a prescription for a medication unsafe for a pregnant mother
• And other issues arising from a failure to provide an adequate standard of care before, during and after birth.

What are the risk factors?

There are some medical conditions or events that can happen during pregnancy and delivery that may increase a baby’s risk of being born with cerebral palsy. These risks include:

Low birthweight and premature birth. Premature babies (born less than 37 weeks into pregnancy) and babies weighing less than 5 ½ pounds at birth have a much higher risk of developing cerebral palsy than full-term, heavier weight babies.  Tiny babies born at very early gestational ages are especially at risk.

Multiple births.  Twins, triplets, and other multiple births — even those born at term — are linked to an increased risk of cerebral palsy. The death of a baby’s twin or triplet further increases the risk.

Infections during pregnancy.  Infections such as toxoplasmosis, rubella (German measles), cytomegalovirus, and herpes, can infect the womb and placenta. Inflammation triggered by infection may then go on to damage the developing nervous system in an unborn baby. Maternal fever during pregnancy or delivery can also set off this kind of inflammatory response.

Blood type incompatibility between mother and child.   Rh incompatibility is a condition that develops when a mother’s Rh blood type (either positive or negative) is different from the blood type of her baby. The mother’s system doesn’t tolerate the baby’s different blood type and her body will begin to make antibodies that will attack and kill her baby’s blood cells, which can cause brain damage.

Exposure to toxic substances.  Mothers who have been exposed to toxic substances during pregnancy, such as methyl mercury, are at a heightened risk of having a baby with cerebral palsy.

Mothers with thyroid abnormalities, intellectual disability, excess protein in the urine, or seizures.  Mothers with any of these conditions are slightly more likely to have a child with CP.

There are also medical conditions during labor and delivery, and immediately after delivery that act as warning signs for an increased risk of CP. However, most of these children will not develop CP. Warning signs include:

Breech presentation.  Babies with cerebral palsy are more likely to be in a breech position (feet first) instead of head first at the beginning of labor. Babies who are unusually floppy as fetuses are more likely to be born in the breech position.

Complicated labor and delivery.  A baby who has vascular or respiratory problems during labor and delivery may already have suffered brain damage or abnormalities.

Small for gestational age.  Babies born smaller than normal for their gestational age are at risk for cerebral palsy because of factors that kept them from growing naturally in the womb.

Low Apgar score.   The Apgar score is a numbered rating that reflects a newborn’s physical health. Doctors periodically score a baby’s heart rate, breathing, muscle tone, reflexes, and skin color during the first minutes after birth. A low score at 10-20 minutes after delivery is often considered an important sign of potential problems such as CP.

Jaundice. More than 50 percent of newborns develop jaundice (yellowing of the skin or whites of the eyes) after birth when bilirubin, a substance normally found in bile, builds up faster than their livers can break it down and pass it from the body. Severe, untreated jaundice can kill brain cells and can cause deafness and CP.

Seizures.  An infant who has seizures faces a higher risk of being diagnosed later in childhood with CP.

Signs and Symptoms of Cerebral Palsy

An infant with cerebral palsy may have muscular and movement problems, including poor muscle tone. Muscle tone refers to a person’s automatic ability to tighten and relax the muscle when required.

Features can include:

• Overdeveloped or underdeveloped muscles, leading to stiff or floppy movements
• Poor coordination and balance, known as ataxia
• Involuntary, slow writhing movements, or athetosis
• Stiff muscles that contract abnormally, known as spastic paralysis
• Crawling in an unusual way
• Lying down in awkward positions
• Favoring one side of the body over the other
• A limited range of movement

Other signs and symptoms include:

• Late achievement of developmental milestones such as crawling, walking, or speaking
• Hearing and eyesight problems
• Problems controlling bladder and bowel movements
• Seizures
• Drooling, and problems with feeding, sucking and swallowing
• Being easily startled

Symptoms normally start to show during the first 3 years of life.

Complications of Cerebral Palsy

Intellectual and Developmental CP Complications

• Intellectual impairment
• Prohibits the person from being able to walk or speak clearly

Physical Complications of Cerebral Palsy

When someone is diagnosed with cerebral palsy, other physical conditions may coexist. This includes:

• Seizure Disorders
• Hydrocephalus
• Vision and Hearing Difficulties
• Oral Issues – overbites, underbites, and gingival hyperplasia.
• Skeletal Issues – scoliosis, humpback, saddleback, and osteoporosis
• Urological Issues – incontinence, or involuntary urination
• Digestive Issues – difficulty eating, sucking, or swallowing
• Pain Issues – Joint and back pain

Cognitive Complications of Cerebral Palsy

Some complications associated with CP are more cognitive (or brain-based). Here are two of the most common:

• Autism Spectrum Disorders
• Speech and Language Issues
• Depression

Diagnosis and Test used for Cerebral Palsy

If your family doctor or pediatrician suspects your child has cerebral palsy, he or she will evaluate your child’s signs and symptoms, review your child’s medical history, and conduct a physical evaluation. Your doctor may refer you to a specialist trained in treating children with brain and nervous system conditions (pediatric neurologist).

Your doctor will also order a series of tests to make a diagnosis and rule out other possible causes.

Brain Scans

Brain-imaging technologies can reveal areas of damage or abnormal development in the brain. These tests may include the following:

Magnetic resonance imaging (MRI). An MRI uses radio waves and a magnetic field to produce detailed 3-D or cross-sectional images of your child’s brain. An MRI can often identify any lesions or abnormalities in your child’s brain.

This test is painless, but it’s noisy and can take up to an hour to complete. Your child will likely receive a mild sedative beforehand. An MRI is usually the preferred imaging test.

Cranial ultrasound. This can be performed during infancy. Cranial ultrasound uses high-frequency sound waves to obtain images of the brain. Ultrasound doesn’t produce a detailed image, but it may be used because it’s quick and inexpensive, and it can provide a valuable preliminary assessment of the brain.

Electroencephalogram (EEG)

If your child has had seizures, your doctor may order an electroencephalogram (EEG) to determine if he or she has epilepsy, which often occurs in people with cerebral palsy. In an EEG test, a series of electrodes are affixed to your child’s scalp.

The EEG records the electrical activity of your child’s brain. If he or she has epilepsy, it’s common for there to be changes in normal brain wave patterns.

Laboratory tests

Laboratory tests may also screen for genetic or metabolic problems.

Additional tests

If your child is diagnosed with cerebral palsy, you’ll likely be referred to specialists for assessments of other conditions often associated with the disorder. These tests may identify:

• Vision impairment
• Hearing impairment
• Speech delays or impairments
• Intellectual disabilities
• Other developmental delays
• Movement disorders

Treatments and Medications

A child may need one or several different types of treatment depending on how severe the symptoms are and what parts of the body are affected. The treatment differs from person to person, depending on each one’s specific needs. Although the initial damage of cerebral palsy in the brain cannot be reversed, earlier and aggressive treatments may help to improve function and adjustments for the young nervous system and musculoskeletal system.

Families may also work with their health care providers and, during the school years, school staff to develop individual care and treatment programs.

Common types of treatment for cerebral palsy include:

Physical therapy and rehabilitation

A child with cerebral palsy usually starts these therapies in the first few years of life or soon after being diagnosed. Physical therapy is one of the most important parts of treatment. It involves exercises and activities that can maintain or improve muscle strength, balance, and movement. A physical therapist helps the child learn skills such as sitting, walking, or using a wheelchair. Other types of therapy include:

Occupational therapy

This type of therapy helps a child learn to do everyday activities such as dressing and going to school.

Recreational therapy

Participating in art programs, cultural activities, and sports can help improve a child’s physical and intellectual skills.

Speech and language therapy

A speech therapist can help a child learn to speak more clearly, help with swallowing problems, and teach new ways to communicate, such as by using sign language or a special communication device.

Orthotic devices

Braces, splints, and casts can be placed on the affected limbs and can improve movement and balance. Other devices that can help with movement and posture include wheelchairs, rolling walkers, and powered scooters.

Assistive devices and technologies

These include special computer-based communication machines, Velcro-fastened shoes, or crutches, which can help make daily life easier.

Medication

Certain medications can relax stiff or overactive muscles and reduce abnormal movement. They may be taken by mouth, injected into affected muscles, or infused into the fluid surrounding the spinal cord through a pump implanted near the spinal cord. For children who have cerebral palsy and epilepsy (seizures), standard epileptic medications should be considered, but these medications may also have negative effects on the developing brain.

Surgery

There are multiple surgical treatments that can help correct movement problems in children with cerebral palsy. However, parents should keep in mind that surgery isn’t right for every child with cerebral palsy.

Surgery is most commonly prescribed for those with spastic cerebral palsy because their increased muscle tone can be reduced to relieve restricted movement. For example, a child who walks on their toes due to high muscle tone in their legs can have those muscles or tendons lengthened, allowing for more normal walking.

Surgeries that can improve mobility in children with high muscle tone include:

Muscle and tendon lengthening – A procedure used to correct contracted muscles or tendons, freeing up movement to walk or use hands.

Tendon transfer – Transferring tendons from one bone to another is intended to give better alignment and motor control, especially in the feet and ankles.

Tenotomy/myotomy – Cutting the tendon/muscle can relieve pain and restrictive movement caused by contractures – a permanent tightening of tendons or muscles.

Neurectomy – Cutting the nerve that controls a specific muscle group can reduce spasticity or rigidity in that area. It is generally used to correct hip dislocations.

Osteotomy – A procedure to realign joints by removing part of the bone.

Arthrodesis – Fusing two bones together can produce stability in some cases.

Selective dorsal rhizotomy – This aggressive procedure involves cutting specific nerves in the spinal column to correct spasticity in various muscle groups throughout the body.

Can cerebral palsy be prevented?

In many cases, the cause of cerebral palsy is not known, so there is nothing that can be done to prevent it. In spite of improvements in the care of pregnant women and sick babies, the number of babies with cerebral palsy seems to be increasing. This is due, in part, to the survival of an increasing number of very premature babies, who are at high risk of cerebral palsy.

However, some causes of cerebral palsy have been identified, and cases of cerebral palsy that result from them often can be prevented.  Rh disease and congenital rubella syndrome used to be important causes of cerebral palsy. Now Rh disease usually can be prevented when an Rh-negative pregnant woman receives appropriate care. Women can be tested for immunity to rubella before pregnancy and be vaccinated if they are not immune.

Babies with severe jaundice can be treated with special lights (phototherapy). Head injuries in babies, a significant cause of cerebral palsy in the early months of life, often can be prevented when babies ride in car seats properly positioned in the back seat of the car. Routine vaccination of babies (with the Hib vaccine) prevents many cases of meningitis, another cause of brain damage in the early months.

A woman can help reduce her risk of preterm delivery when she seeks early monitoring (ideally starting with a pre-pregnancy visit) and regular prenatal care and avoids cigarettes, alcohol and illicit drugs.