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Van Haastart and colleagues have explored the link between disturbed motor function and periventricular leukomalacia (PVL), diagnosed during the period just after birth in a group of very preterm babies. The children were examined at four time points: at an average age of 9 months, 16 months, 24 months, and 7 years (although the age range at this last time point was extraordinarily wide, ranging between just over 2 years and 16 years). The striking finding was that there was a very strong association between the early diagnosis of PVL and later gross motor outcome. Although the relationship between different PVL grades in preterm infants and subsequent gross motor function classified using the Gross Motor Function Classification System (GMFCS)1 has not previously been reported, the link between PVL and cerebral palsy (CP) is not novel. Unsurprisingly, the children with the worst grade of PVL generally had the worst outcome.
The issue which troubles clinicians is what to do with the information. Their difficulty is that the association is not invariable. As the authors point out, only infants with PVL who subsequently developed CP were eligible for the study and several studies have shown that between 4 and 10% of infants with a cranial ultrasound diagnosis of grade I PVL will go on to develop CP. Furthermore, magnetic resonance imaging studies have shown that a major problem for these children is diffuse white matter injury (WMI),2–4 which is associated with cognitive impairment. Van Haastart and colleagues suggest that their findings have implications for counselling and intervention. But the difficulty is that, while there is a strong association between grade of PVL and outcome, there are individuals who differ from the general rule. For example, two children (2/26) with the severest grade of PVL had the mildest outcome as assessed by the GMFCS. So how should parents be counselled? And what sort of interventions are available?
Clinicians need to advise parents reliably and treat children to optimize outcome. But most children with diffuse WMI show no physical abnormality until they are several months old and learning difficulties sometimes only become apparent after several years. The problem is that intervention in the absence of physical signs has not been shown to have any effect on motor outcome.5,6 One approach is to advise parents about the uncertainty of outcome, advise them about what to look out for, and explain that all possible support will be given to them if their child does develop signs of impairment. The advice is often to ‘travel hopefully’.
As with all good pieces of research, this work by van Haastart and colleagues raises further questions. What effect does this well-meant information have for parents, are there interventions to improve outcome in the light of the diagnosis of diffuse WMI, and, most importantly, can WMI be prevented?