Providing important evidence for the major causal contributors to cerebral palsy in Africa

Cerebral palsy (CP) describes a group of posture and movement disorders that limit activity and are caused by non-progressive lesions in the developing foetal or infant brain. It is a broad term that encompasses a spectrum of aetiologies and phenotypes and may be associated with a range of comorbid conditions, including seizures, intellectual disability, behavioural problems and sensory disorders 1. CP is one of the most common neurological diagnoses in children and has been reported to occur in 2–2.5 of 1,000 live births across the World. Very little has been reported on this condition in the African context, in common with many neurological conditions in childhood. In particular, the range of aetiologies in resource-poor contexts is widely held to be different from the most common causes of CP in well-resourced environments 2. The study by Kakooza-Mwesige et al. 3 in this issue of Acta Paediatrica makes an important contribution to the body of published literature in this area. Their paper describes an observational study of the brain computed tomography (CT) scan findings in a clinic population of children with CP in Uganda, East Africa. This is important information from a high prevalence region for CP and adds clinically relevant data from an understudied population. Neuroimaging is considered an important investigation in the work-up of children with CP 4. The American Academy of Neurology practice parameters include recommendations for the routine neuroimaging of childhood CP for those in whom the aetiology has not yet been established. Although the neuroimaging findings associated with CP do not always provide definitive aetiological diagnosis, it remains, in conjunction with a detailed history and clinical examination, the most useful investigation in this condition for determining the nature and timing of the insult to these young brains 5. Early imaging may also be able to provide families with important information on their child's prognosis and recurrence risk and help to inform medical management. However, in environments with poorly resourced medical systems, neuroimaging facilities, such as CT scans or magnetic resonance imaging scans, are often much less accessible. This is especially true of sub-Saharan Africa, where many countries only have one scanner, or none at all, and specialised facilities of this type may not be available for those who cannot pay for the investigation themselves 2. As a result, neuroimaging studies of children with CP in low-income and middle-income countries are limited. Kakooza-Mwesige et al.'s paper reports on the neuroimaging patterns of children with CP attending a tertiary referral centre in Uganda, East Africa. The study was performed in a hospital clinic population with CP and included 78 children aged two to 12 years of age. Brain CT scans were independently reviewed by two radiologists, who were blinded to the patients’ clinical status. Images were classified according to a six-category classification system similar to that used in other large CP neuroimaging studies. Abnormal CT scans findings were detected in 69% of the study sample. Distribution patterns reported in this cohort included primary white matter injuries (WMI) (4%), primary grey matter injuries (GMI) (44%) and normal scans (31%). Children with a history of hospital admission following birth were three times more likely to have primary GMI, with an odds ratio of 2.8 and 95% confidence interval of 1.1, suggesting a perinatal period with medical complications. This pattern differed significantly from the results of a review of neuroimaging studies reporting CP cohorts from Sweden, Germany, Australia, Canada and the United States of America, which ranged in size from 56 to 563 children. 5. In this review, Reid et al. reported abnormal neuroimaging findings in 86% of the children included in the cited studies. Furthermore, patterns of neuroimaging abnormalities differed, although with some heterogeneity between cohorts, with primary WMIs detected in 19–45% of children, primary GMIs in only 14–22% and focal vascular insults in approximately 10%. Only 13.8% of the children in this review had normal scans. There was a remarkable overall consistency in the findings from the neuroimaging studies in this review across well-resourced environments. The differences highlighted above between these studies and the Ugandan cohort suggest a number of important insights. The emphasis in aetiology in the hospital cohort was weighted towards term insults, with only a fraction of the cohort having a primary WMI, which is generally associated with preterm insults. Not only does this imply a high prevalence of term insults, but also a reduced survival in preterm infants. The other key point to note is that the Ugandan cohort comprised 55% of children with severely impaired gross motor function, described as a gross motor function classification of IV or V. This is a far higher proportion than in the population-based samples cited above. Although the children with severe motor impairment were more likely to have a primary GMI when the population-based samples were separated out, that proportion still did not reach the 44% described in the Ugandan cohort. Other studies that have reported presumed aetiology in the African context have similarly identified birth asphyxia, kernicterus, congenital and neonatal infections to be common aetiologies in CP, with prematurity or low birth weight identified as a significant additional aetiology in only two studies 2. This is in contrast with studies from the United States and Europe, in which prematurity or low birth weight was one of the major risk factors identified in almost all of the cohorts 5. The relatively high proportion of CT scans where no abnormality was detected may partly be explained by the poorer tissue differentiation and spatial resolution, particularly of the deep grey matter structures, compared to MRI scans. The paper by Kakooza-Mwesige et al. 3 has provided important evidence for the major causal contributors to CP in Africa. Identifying potentially preventable aetiologies, such as term birth asphyxia, central nervous system infections and kernicterus, is key to highlighting intervention priorities in these contexts. Prematurity and low birth weight appear to be much smaller contributors to CP in Africa, in proportional terms, than in high-resource settings, possibly because of relatively poor survival among these infants. This was borne out in this study. Future research investigating interventions that prioritise the risk factors prevalent in these high-risk, low-resource environments are urgent. Intervention strategies that focus on the conditions that result in better survival of all term and preterm infants in Africa, as well as the neurological health of surviving children, will need to address access to resources and overcome barriers to care, as well as specific medical interventions, in order to have significant impact.

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