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Advances in neuroimaging have been central to the improved recognition, diagnosis, investigation, and management of acute focal neurological deficits in children. As a third of such children will have a non-vascular aetiology, imaging is mandatory in acute assessment. Magnetic resonance imaging (MRI), in particular, has enabled early identification of cerebral ischaemia, and differentiation of vascular stroke syndromes from the ‘stroke mimics’ which are common in paediatric practice.1

In their paper, Buerki et al.2 report multicentre neuroimaging data on children with arterial ischaemic stroke (AIS) in Switzerland between 2000 and 2006. It is surprising that a quarter of the children did not have MRI and only half had magnetic resonance angiography (MRA) of the circle of Willis (even less had MRA of the cervical circulation) within the first 2 weeks. The aetiologies underlying childhood AIS are diverse and often multiple: up to two-thirds of children will have non-atherosclerotic abnormalities of the cerebral circulation – collectively termed ‘arteriopathies’,3 a term reflecting current radiological rather than aetiological descriptions. The morphology and evolution of cerebral arteriopathies are critical to informing secondary prevention and prognosis.3–5 MRA can conveniently be combined with brain MRI and should include imaging of the aortic arch to the circle of Willis. Time-of-flight MRA, whilst non-invasive, is limited by overestimating stenotic lesions and by spatial resolution; this may partly be addressed by contrast-enhanced MRA but as yet there is limited paediatric experience. Intra-luminal vascular imaging techniques such as computed tomography (CT) angiography and catheter cerebral angiography have a continuing role, despite exposure to ionising radiation, especially in the evaluation of possible dissection, vasculitis, or where MRA is not diagnostic. Recommendations regarding the optimal vascular imaging technique in various settings are likely to evolve over the next few years but the importance and high yield of including cerebrovascular imaging as part of the evaluation of acute AIS in children cannot be re-iterated too strongly. Indeed, the yield of vascular imaging in Buerki et al.’s study was around 80%.

Buerki et al. confirmed that CT may be normal early on or in posterior circulation AIS and that diffusion-weighted MRI is superior for detection of acute ischaemia. Lesion distribution was as described in other, hospital-based series, with a predominance of anterior circulation infarcts and of stroke subtypes. Of note, lesion distribution on MRI did not enable identification of the underlying risk factors – emphasising the importance of comprehensive evaluation in all cases. This is further reinforced by the relatively low proportion of apparently idiopathic cases. Whilst the radiological pattern may not enable omission of investigations, specific aetiologies may need to be considered and sought in particular circumstances, for example, vertebral dissection in posterior circulation infarcts.

Current guidelines do not provide recommendations on re-imaging in the long-term management of childhood AIS. As demonstrated here, re-imaging is exceptional in current clinical practice and there is a need to determine whether, when, and how this should be undertaken and used to inform secondary preventative strategies. In day-to-day practice delayed recognition remains a major barrier to early diagnosis and imaging in childhood AIS. Even in the most privileged healthcare settings practical barriers to acute neuroimaging include access to general anaesthesia or to MRI itself. The drive to improve these factors will gain momentum with the potential for hyperacute treatments and evidence-based secondary preventative strategies – issues which are being actively explored as part of collaborative multicentre ventures such as the International Paediatric Stroke Study.6 It is unlikely that thrombolysis will prove either appropriate or timely for the majority of children with AIS. However, early recognition of the correct diagnosis and underlying risk factors enabling prevention of recurrence5 and of secondary complications are already possible with the prompt and targeted use of imaging techniques widely available in clinical practice.

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