Cerebral Palsy
(CP · Little's Disease)
In this condition factsheet:
The Facts on Cerebral Palsy
Cerebral palsy is a name given to a group of different nervous system disorders that are present at birth or appear in the first 3 years of life. What these disorders have in common is that the underlying brain damage doesn't get worse over the years. They also all cause some degree of damage in the motor neurons of the brain, affecting coordination and muscle strength.
Overall, cerebral palsy affects somewhere between 1 in 500 and 1 in 1,000 newborns, though some of these are only mildly affected. The risk is highest in premature and underweight babies. The number of new cases of cerebral palsy has actually risen slightly in recent years, partly because better intensive care is keeping more premature babies alive but also because fertility treatments have led to a rise in twin and multiple births, which are more likely to result in a baby with cerebral palsy.
Other risk factors for the development of cerebral palsy include:
- having a birthing parent who has an infection (e.g., rubella [German measles], toxoplasmosis, herpes, cytomegalovirus) while pregnant
- having a birthing parent with an incompatible blood type (Rh incompatibility is an immune problem in which the birthing parent generates antibodies that attack and destroy red blood cells in the fetus, interfering with oxygen supply to the child's organs - it rarely happens in first pregnancies)
- being exposed to toxic substances in the womb
- having a birthing parent with intellectual disability, or with a history of thyroid problems or seizure disorders.
- having a complicated delivery (e.g., breech birth).
- having a low Apgar score (a test carried out several times in the hours after delivery that assigns a score based on heart rate, reflexes, skin colour, and muscle tone).
- having severe jaundice after birth, especially if left untreated.
- having seizures as an infant.
Causes of Cerebral Palsy
Although cerebral palsy is often considered a congenital (present at birth) syndrome, it can also develop after birth. A brain injury resulting from a brain infection (e.g., meningitis, encephalitis) or from a fall or accident such as a near drowning is termed acquired cerebral palsy. On the other hand, congenital cerebral palsy is a result of something going wrong during fetal development or during the birth process itself. It used to be believed that lack of oxygen during delivery was the main cause, but researchers now think this only account for about 10% of cases.
A fetus develops from a single cell, which divides repeatedly to eventually become billions of cells. During the process, groups of cells become specialized to form all the different body tissues. Likewise, various types of nerve cells form and migrate to take up their proper places throughout the brain. This process is highly complex and, not surprisingly, errors sometimes occur that disturb the normal architecture of the brain.
Errors could occur as a result of the following:
- A fetal stroke that cuts off blood supply to the developing brain, causing brain damage. This can be caused by maternal infections or high blood pressure.
- Maternal or fetal infections can damage the white matter in the brain, which causes nerve transmission problems between the brain and the body.
- Mutations can occur in genes that control fetal brain development, caused by maternal infections, fever, trauma, or fetal exposure to toxins.
- Prolonged lack of oxygen to the brain because of a complicated labour and delivery, severely low maternal blood pressure, uterus rupture, or problems with the placenta or umbilical cord.
We are only now beginning to understand some of the issues surrounding the development of the fetal brain. Hopefully, more research in this area will allow us to eventually explain the exact causes of cerebral palsy.
Symptoms and Complications of Cerebral Palsy
The signs of cerebral palsy are usually first noticed by the parents after the child is 6 months old. Likely first signs include:
- adopting unusual positions and favouring one side of the body when they move
- excessive rigidity (increased muscle tone) or floppiness (decreased muscle tone)
- crossed eyes
- failure to develop at a normal rate – not reaching milestones like sitting up, smiling, or walking
- muscle wasting, slow or uneven growth
- seizures
- unresponsiveness or apparent deafness
There is no set pattern of symptoms in cerebral palsy because it's an umbrella term covering many symptoms. However, there are certain broad categories that distinguish the various motor (muscle) symptoms.
- Spastic cerebral palsy is the most common form, affecting about three-quarters of sufferers. Muscles tend to be permanently contracted. This may be severe enough to bend the joint permanently or to cause paralysis. The spasticity may affect both legs, both arms, all four limbs, or one leg and one arm. Affected limbs may grow more slowly than healthy ones, producing unusually small feet, legs, and hands. People with spastic cerebral palsy who are able to walk often have a scissors gait, in which the knees almost touch and the feet cross inwards over an imaginary line drawn down the centre of the body.
- Athetoid cerebral palsy affects 1 in 5 sufferers. It's characterized by slow, writhing movements, usually in the limbs, but it may also affect facial muscles including the tongue. This can lead to drooling, strange facial expressions, and an inability to form some words or sounds. Speech defects due to muscle disorders (dysarthria) should be distinguished from language difficulties due to mental retardation, which is a very different problem.
- Ataxic cerebral palsy affects fewer than 1 in 20 sufferers. Poor coordination and depth perception makes people with ataxic cerebral palsy unsteady walkers, with a wide-based gait. They also have difficulty with quick and precise movements like writing. They may suffer from intention tremor, in which the arm or hand trembles when reaching for an object, and the trembling gets worse the closer the hand gets to the target.
A great many people with cerebral palsy have mixtures of these forms. The most common mixture is spastic-athetoid cerebral palsy. In all types, the symptoms can be very mild or very severe. Some people's only challenge is shaky writing, while others are paralyzed from the neck down.
A wide range of other problems can go along with nerve and muscle symptoms in cerebral palsy. By far the most important is intellectual impairment, which can range from none to severe impairment. But even with normal intelligence, the vision, hearing, and speech problems; social isolation; resentment; and depression that can accompany cerebral palsy can lead to learning disabilities unless the child is helped and encouraged every step of the way.
Strabismus is a common problem for people with cerebral palsy. This symptom is often described as crossed eyes. But in young children whose eyes aren't aligned, there's a tendency for the brain to completely ignore signals from one eye, leading to major deterioration of eyesight in that eye. Deafness, while not common, is more common in children with cerebral palsy than in the general population. Sometimes, the sense of touch is also deficient.
Bladder and bowel function are often impaired by the lack of proper nervous signals coming from the brain. This can lead to constipation or, most likely, urinary incontinence, which can take several forms. Bedwetting, a sudden release upon exercise or coughing, or a constant dribble are all possible. The same lack of nervous signals can make chewing and swallowing difficult.
Epilepsy is common in people with cerebral palsy. Seizures may be mild or severe.
The most common complication of cerebral palsy is muscle contracture, which generally occurs in children. As the bones grow, the muscles normally keep pace. In cerebral palsy, there's a tendency for sufferers not to use their weaker or less coordinated limbs, leading to muscle atrophy. This can prevent the muscle from growing with the bone, which can cause the joint to become permanently flexed and paralyzed. Once this happens, surgery is usually required to fix it.
Symptoms don't generally get worse over time, as the underlying disease isn't progressive. Atrophy, however, can worsen muscular symptoms and, in children, prevent proper growth. Weaker, less coordinated limbs often end up withered or undersized.
There's a lack of research on the effects of cerebral palsy in older adults. Some doctors believe that people with cerebral palsy may age faster after middle age, but for the moment there's no evidence one way or the other. Statistics on life expectancy for people with this disease are also lacking.
Despite these unknowns, cerebral palsy is certainly not considered a fatal condition.
