Epidemiology
Cerebral palsy is the most common source of childhood physical disability and affects people all over the world. Current research seems to indicate that the number of people who have cerebral palsy is increasing. This is despite recent experimental identification of risk factors for cerebral palsy and advances in medical prevention of the disease. Researchers, doctors and other medical professionals continue to seek effective preventative and treatment strategies for cerebral palsy.
1. Risk factors and clinical profiles in Turkish children with cerebral palsy: Analysis of 635 cases
The aim of the study was to investigate risk factors, clinical profiles and gross motor function levels of Turkish children with cerebral palsy (CP). A total of 625 consecutive children with CP, who were rehabilitated in the pediatrics rehabilitation clinic between 2000 and 2004 years, were included. Factors causing CP were investigated by interviewing the families and by scanning medical files. Risk factors were recorded as consanguineous marriage, maternal disorder, preterm birth, birth asphyxia, low birth weight, multiple pregnancy, neonatal convulsion, kernicterus, postnatal central nervous system infection and brain injury. Swedish classification was followed in CP typing. Of 625 children with CP, 370 (59.2%) were males and 255 (40.8%) were females, with ages ranging between 2 and 13 years (the mean age was 5.11+/-2.19 years). It was determined that 47.8% of the cases were spastic diplegic CP, 27.7% were spastic tetraplegic CP, 12.8% spastic hemiplegic CP and 11.7% were other types (ataxic, dyskinetic and mixed CP types). The most frequently encountered risk factors were low birth weight (45.1%), preterm birth (40.5%), birth asphyxia (34.6%) and consanguineous marriage (23.8%). Low birth weight, preterm birth, birth asphyxia and consanguineous marriage were top-ranked risk factors that were determined in Turkish children with CP. Compared with other countries, consanguineous marriage is still an important problem in Turkey.
[Erkin, G., Delialioglu, S. U., Ozel, S., Culha, C. & Sirzai, H. (2008). Risk factors and clinical profiles in Turkish children with cerebral palsy: Analysis of 635 cases. International Journal of Rehabilitation Research, 31(1), 98-91.]
2. Cerebral palsy
The clinical pattern and etiology of 544 cases of cerebral palsy were studied retrospectively. Of these cases, 354 (65.1%) were males. Four hundred and ninety seven (91.4%) cases were of spastic type. Hypotonic, ataxic and athetoid cerebral palsy were observed in 5.5, 1.5 and 1.3% cases, respectively. There was one case each of tremor and mixed type. In the spastic group, quadriplegia comprised the maximum number of cases (34.9%). Hemiplegia (28.7%) and diplegia (21.9) were also common. Mental retardation was found in 47.2%, while speech impairment was observed in 37% cases. Other handicaps included visual (9%), seizures (8.8%), and auditory handicap (2.9%). The etiological factors were prenatal in 7.7% cases, natal in 43.8% cases and postnatal in 26.1% cases. More than one etiological factor was observed in 14.5% cases, while in 7.9% cases, no apparent cause could be found.
[Srivastava, V. K., Laisram, N. & Srivastava, R. K. (1992). Cerebral palsy. Indian Pediatrics, 29(8), 993-6.]
3. Incidence and risk factors for cerebral palsy in infants with perinatal problems: A 15-year review
OBJECTIVE: Cerebral palsy (CP) is associated with prenatal, perinatal and postnatal factors. This is a retrospective case-control study aiming to determine the frequency of CP and examine risk factors for CP among infants cared for in the Neonatal Intensive Care Unit (NICU) covering Northwest Greece. DESIGN AND PATIENTS: All neonates who were admitted to the NICU during the period 1989-2003 inclusive, and subsequently developed CP, were enrolled in the study, with matched controls. The incidence of CP was evaluated according to gestational age (GA): GA<34 weeks (group A) and GA>34 (group B), and study period: 1989-1996 (period I) and 1997-2003 (period II, during which intrauterine transfer and prenatal steroids were used). RESULTS: CP was diagnosed in 78 children, 55 in group A and 23 in group B. The incidence of CP increased significantly with decreasing GA. Survival without CP increased significantly in children of GA<34 weeks during period II. The main factors associated with CP, identified by multivariate analysis, were (odds ratios, confidence interval), for group A: being small for gestational age (SGA) (2.5, 1.2-4.5) and patent ductus arteriosus (PDA) (3.4, 1.3-9.2) in period I, periventricular leucomalacia (PVL) (27, 4.8-209), prolonged rupture of membranes (PROM) (5.6, 1.8-18) and duration of mechanical ventilation (1.1, 1.05-1.2) in period II, and for group B: SGA (3.6, 1.3-9.9), neonatal transfer (3.06, 1.2-7.6), duration of mechanical ventilation (1.1, 1.06-1.25) and sepsis-meningitis (4.3, 1.2-16). CONCLUSION: Improvement in survival without CP was observed in infants of GA<34 weeks during the later period of the study, and risk factors for CP in preterm infants depended on the study period. PVL, PROM and PDA were the most powerful independent predictors of CP in children of GA<34 weeks and SGA, neonatal transfer and sepsis/meningitis in children of GA>34 weeks.
[Drougia, A., Giapros, V., Krallis, N., Theocharis, P., Nikaki, A., Tzoufi, M. & Andronikou, S. (2007). Incidence and risk factors for cerebral palsy in infants with perinatal problems: A 15-year review. Early Human Development, 83(8), 541-7.]
4. Epidemiology of stillbirth and fetal central nervous system injury
The epidemiology of stillbirth and fetal central nervous system (CNS) injury is described with some emphasis on maternal and feto-placental risk factors. To maximize utility of the discussion and because it also represents the classical manifestation of fetal CNS injury, we have selected cerebral palsy (CP) to illustrate the epidemiologic aspects of injury to the fetal CNS in general. While trends in stillbirth rates have modestly decreased over time, those of CP seem to be increasing. Interestingly, both stillbirth and CP share traditional as well as emerging risk factors lending credence to the hypothesis that fetuses that would previously have been stillborn are increasingly surviving albeit with some form of morbidity. The existence of shared risk factors also suggests that in some cases of stillbirth fetal CNS injury precedes the in utero fetal demise. Pregnant women bearing these risk indicators represent potential candidates for appropriate and tailored protocols for antenatal fetal testing.
[Salihu, H. M. (2008). Epidemiology of stillbirth and fetal central nervous system injury. Seminars in Perinatology, 32(4), 232-8.]
5. Prevalence of four developmental disabilities among children aged 8 years—Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1996-2000
PROBLEM/CONDITION: In the United States, developmental disabilities affect approximately 17% of children aged <18 years, resulting in substantial financial and social costs. REPORTING PERIOD: 1996 and 2000. DESCRIPTION OF SYSTEM: The Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) monitors the occurrence of mental retardation, cerebral palsy, hearing loss, vision impairment, and autism spectrum disorders among children aged 8 years in the five-county metropolitan Atlanta area (Clayton, Cobb, DeKalb, Fulton, and Gwinnett). MADDSP uses a multiple source ascertainment methodology. RESULTS: During 1996, the prevalence of mental retardation was 15.5 per 1,000 children aged 8 years; it decreased to 12.0 per 1,000 in 2000. The overall prevalence of cerebral palsy was 3.6 per 1,000 in 1996 and 3.1 per 1,000 in 2000. The prevalence of mental retardation and cerebral palsy was highest among males and black children. The prevalence of hearing loss was 1.4 per 1,000 in 1996 and 1.2 per 1,000 in 2000; the prevalence of vision impairment during 1996 was 1.4 per 1,000 and 1.2 per 1,000 in 2000. Minimal differences by study year were observed in the prevalence of all four disabilities when examined by sex, race, and severity. INTERPRETATION: The prevalence of these four select developmental disabilities in MADDSP was higher in 1996 than the annual average prevalence estimates for these disabilities during previous MADDSP study years (1991-1994) study years; the highest increase was observed among children with mental retardation. However, prevalence estimates during 2000 were more consistent with the estimates from the early 1990s. Data from additional surveillance years (2002 and beyond) are needed to determine if the prevalence for 1996 was an anomaly and to continue to monitor trends in the prevalence of developmental disabilities over time. PUBLIC HEALTH ACTIONS: MADDSP data will continue to be used to examine trends in the occurrence of these disabilities over time, facilitate the development and implementation of appropriate intervention programs, and provide a framework for conducting population-based etiologic studies.
[Bhasin, T. K., Brocksen, S., Avchen, R. N., Van Naarden Braun, K. (2006). Prevalence of four developmental disabilities among children aged 8 years—Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1996-2000. Morbidity and Mortality Weekly Report: Surveillance Summaries, 55(1), 1-9.]
6. The epidemiology and causes of cerebral palsy
Cerebral palsy is the commonest physical disability in childhood, occurring in 2.0 to 2.5 per 1000 live births. Although the total number of children with cerebral palsy has remained stable or increased slightly since 1970, there has been a consistent rise in the proportion of cerebral palsy associated with preterm and very preterm births. Known causes of cerebral palsy—whether prenatal, perinatal or postnatal—must be distinguished from risk factors or associations. Much is known about such risk factors which, alone or in combination, may indirectly result in cerebral palsy. Causes and risk factors implicated in cerebral palsy are discussed in detail, together with directions for future research.
[Reddihough, D. S. & Collins, K. J. (2003). The epidemiology and causes of cerebral palsy. The Australian Journal of Physiotherapy, 49(1), 7-12.]
7. Descriptive epidemiology of cerebral palsy
The paper reviews the recent epidemiological literature on the prevalence of cerebral palsy (CP), including age, sex, and prevalence rates. Special attention is given to the clinical characteristics, including the forms of CP and the incidence of epilepsy, intellectual impairment, and defects of vision, speech, and hearing. Trends in the prevalence of CP are also considered, with particular reference to improvement in perinatal intensive care.
[Zgorzalewicz, B., Mieszczanek, T. & Zgorzalewicz, M. (2001). Descriptive epidemiology of cerebral palsy. Ortopedia, Traumatologia, Rehabilitacja, 3(4), 467-71.]
8. A changing pattern of cerebral palsy. Declining trend for incidence of cerebral palsy in the 20-year period 1970-89
In a population-based study cerebral palsy (CP) was diagnosed in 110 cases (2.4 per 1000) among children live born with birth weight > or = 500 g (n = 45,976) during the 20-year-period 1970-89 (CP cases with a postneonatal etiology excluded). The CP-incidence showed a linear trend of decline from 2.8 per 1,000 in the first 5-year-cohort born 1970-74, to 2.0 per 1,000 in children born 1985-89 (p = 0.17). Birth weight specific CP-incidence showed a trend of decline in very low birth weight infants (500-1,499 g) and in infants > or = 2,500 g from the first 10-year-cohort born 1970-79 to the second born 1980-89. The same trend occurred for the incidence of spastic diplegia in total and in children born preterm. These trends of decline did not achieve statistical significance (p > 0.05). The CP-incidence was 36.7 and 11.3 times higher among infants with birth weight 500-1,499 g and 1,500-2,499 g respectively compared to infants > or = 2,500 g (p < 0.01). 15.9% of the decline in CP-incidence from the first to the second 10-year-cohort could be explained by a decreased low birth weight rate (500-2,499 g) in the population, from 4.2% 1970-79 to 3.8% 1980-89 (p < 0.05). The origin of CP was considered prenatal in 22 (20%), perinatal in 47 (42.7%), and undifferentiated in 41 (37.3%) of the cases. More CP-children born in the 10-year-period 1980-89 were treated with mechanical ventilation in the neonatal period (13/46; 28.3%) than those born in the 10-year-period 1970-79 (4/64; 6.3%) (p < 0.01). The neonatal mortality rate declined significantly from 7.2 per 1,000 in the first to 3.9 per 1,000 in the last 10-year-cohort respectively (p < 0.01). Birth weight-specific neonatal mortality rates declined more than 50% in all weight groups (p < 0.01). The results are contradictive to other investigations showing increased CP-incidence following improved survival rates in low birth weight infants, and may reflect a different pattern for development of perinatal care (organization, intensive care). The overall effect of mechanical ventilation may be improved survival and prevention of brain damage, though the percentage of ventilated CP-children increased. Preventing low birth weight should be a main strategy for preventing CP.
[Meberg, A. & Broch, H. (1995). A changing pattern of cerebral palsy. Declining trend for incidence of cerebral palsy in the 20-year period 1970-89. Journal of Perinatal Medicine, 23(5), 395-402.]