Risk factors for intellectual disability in children with spastic cerebral palsy

BACKGROUND: Cerebral palsy (CP) is a non-progressive disorder of posture and movement caused by prenatal or perinatal lesions of the brain. Children with CP are also at increased risk of other disabilities, for example, intellectual disability. Previous studies suggest the risk of intellectual disability varies in complex ways according to the type of motor impairment and perinatal factors such as gestational age. OBJECTIVE: To determine the patterns of risk of intellectual disability in children with spastic CP. DESIGN: Cross-sectional, population-based study using the Northern Ireland Cerebral Palsy Register. PARTICIPANTS: Persons born in 1981–2008 with congenital bilateral or unilateral spastic CP (N=1452). OUTCOME MEASURE: The outcome measure was severe intellectual disability (IQ <50), as reported by clinicians known to the child. Data pertaining to CP subtype, sex, gestational age, birth weight and functional level were included in analyses. RESULTS: Severe intellectual disability was significantly more prevalent in children with bilateral spastic CP (BSCP) compared with children with unilateral spastic CP (χ² (2)=162.60, p<0.001). Compared with very preterm infants with BSCP, the risk of intellectual disability increased in moderately preterm (OR=3.97, 95% CI 1.04 to 15.23) and at-term (OR=2.51, 95% CI 1.16 to 5.44) children with BSCP. CONCLUSIONS: Children with BSCP are at increased risk of intellectual disability, with those born at term at the highest risk. The findings highlight the importance of early screening, particularly for children with BSCP born at term.