Any discussion of the causes of cerebral palsy must first begin by conceding that the condition does not have single, simple cause but is instead multifactorial. In other words, cerebral palsy is not a single condition but rather a term that describes many similar and overlapping neurological conditions. Therefore the possible causes of cerebral palsy are several. Even more difficult is that in as many as four out of five cases of cerebral palsy, the precise cause is not known. That said, there are many things that we do know about the etiology of cerebral palsy and identifying those causes is the first step in preventing future children from developing the condition.
Features Common to All Causes of Cerebral Palsy
Despite being a complex and heterogeneous condition, all cases of cerebral palsy are ultimately caused by a neurological problem—namely a lesion in the brain. The lesion is acquired at some point early in development, either during gestation while the fetus is in the mother’s womb, during or soon after delivery, or any time up to two years after the child is born. Since brain development continues during the firsttwo years of life, an insult during this time can lead to cerebral palsy later on.
Prenatal Causes of Cerebral Palsy
When cerebral palsy occurs during gestation, that is, during the time that the mother is carrying the baby in her womb, the precise cause is often never determined. Nevertheless, several potential prenatal causes have been identified:
- Infection within the uterus
- Thyroid abnormalities and/or iodine deficiencyin the mother
- Methylmercury exposure during pregnancy
- Seizure disorder, such as epilepsy, in the mother
- Multiple gestation (twins, triplets, etc.)
As with any risk factor, the simple occurrence of one of the above situation does not necessarily mean that a child will develop cerebral palsy; however studies of children with the condition have found that that they possess one or more of the above factors more often than children without the condition.
Perinatal Causes of Cerebral Palsy
Perhaps surprising to some, complications during delivery account for only about 6 percent of cerebral palsy cases. Of this 6 percent, the main cause is sustained asphyxia to the newborn leading to brain damage. Researchers have identified several risk factors associated with cerebral palsy that is acquired during the birthing process. An infant born at or before 32 weeks gestation and/or weighing less than 5.5 pounds is at increased risk. Another size-related risk factor is intrauterine growth retardation, that is, the fetus not growing to its expected size at a given gestational age. Also, certain complications such as bleeding within the brain and trauma raise the risk of the newborn developing cerebral palsy.
Postnatal Causes of Cerebral Palsy
As mentioned, cerebral palsy can be acquired at any point up to two years of age. Cerebral palsy acquired during the postnatal period (i.e. time after delivery) accounts for 10 – 20 % of all cases. Postnatal causes of cerebral palsy include:
- Bacterial meningitis
- Viral encephalitis
- Hyperbilirubinemia (abnormally high bilirubin in the blood; kernicterus)
- Problems with heart and/or lung development
- Head trauma such as motorvehicle collisions, falls, or child abuse
Again, not every instance of one of the above factors will lead to cerebral palsy, yet children with cerebral palsy that is acquired during the postnatal period will often have experienced one or more of the preceding issues.