Skeleton
For bones to attain their normal shape and size, they require the stresses from normal musculature. People with cerebral palsy are at risk of low bone mineral density. The shafts of the bones are often thin (gracile), and become thinner during growth. When compared to these thin shafts (diaphyses), the centres (metaphyses) often appear quite enlarged (ballooning). Due to more than normal joint compression caused by muscular imbalances, articular cartilage may atrophy,: 46  leading to narrowed joint spaces. Depending on the degree of spasticity, a person with CP may exhibit a variety of angular joint deformities. Because vertebral bodies need vertical gravitational loading forces to develop properly, spasticity and an abnormal gait can hinder proper or full bone and skeletal development. People with CP tend to be shorter in height than the average person because their bones are not allowed to grow to their full potential. Sometimes bones grow to different lengths, so the person may have one leg longer than the other.Children with CP are prone to low trauma fractures, particularly children with higher Gross Motor Function Classification System (GMFCS) levels who cannot walk. This further affects a childs mobility, strength, and experience of pain, and can lead to missed schooling or child abuse suspicions. These children generally have fractures in the legs, whereas non-affected children mostly fracture their arms in the context of sporting activities.Hip dislocation and ankle equinus or plantar flexion deformity are the two most common deformities among children with cerebral palsy. Additionally, flexion deformity of the hip and knee can occur.
Term infants
In babies that are born at term risk factors include problems with the placenta, birth defects, low birth weight, breathing meconium into the lungs, a delivery requiring either the use of instruments or an emergency Caesarean section, birth asphyxia, seizures just after birth, respiratory distress syndrome, low blood sugar, and infections in the baby.As of 2013, it was unclear how much of a role birth asphyxia plays as a cause. It is unclear if the size of the placenta plays a role. As of 2015 it is evident that in advanced countries, most cases of cerebral palsy in term or near-term neonates have explanations other than asphyxia. Genetics
Cerebral palsy is not commonly considered a genetic disease. About 2% of all CP cases are expected to be inherited, with glutamate decarboxylase-1 being one of the possible enzymes involved. Most inherited cases are autosomal recessive. However, the vast majority of CP cases are connected to brain damage during birth and in infancy. There is a small percentage of CP cases caused by brain damage that stemmed from the prenatal period, which is estimated to be less than 5% of CP cases overall. Moreover, there is no one reason why some CP cases come from prenatal brain damage, and its not known if those cases have a genetic basis. Early childhood
After birth, other causes include toxins, severe jaundice, lead poisoning, physical brain injury, stroke, abusive head trauma, incidents involving hypoxia to the brain (such as near drowning), and encephalitis or meningitis.