Perinatal Arterial Ischaemic Stroke (PAIS)

Before the onset of modern neuroimaging methods it was thought that cerebral infarction was a rare condition, however, the prevalence is now thought to be around 0.5/1000.

The most common type of neonatal cerebral infarction in the full-term infant is an ischaemic lesion in the territory of the middle cerebral artery, with the left more commonly involved than the right. In the majority of cases no underlying cause is found, although there is an increase in the incidence of heterozygosity for factor V Leiden.

Otherwise healthy babies present with seizures, often focal, in the first days of life. There may be some asymmetry on neurological examination, but this is often missed.

Cranial ultrasound examination is often normal although there may be ill defined areas of increased echodensity.MRI is the imaging modality of choice. In the acute phase it appears as a ‘missed cortex’; diffusion weightedimaging (DWI) shows a dramatic increase in signal intensity in the infarcted area.

Despite the large size of these lesions the prognosis is remarkably good with only 1 in 5 having motor problems in later life – usually a hemiplegia. The risk of hemiplegia is greater if the infarct involves the basal ganglia and internal capsule; there also appears to be an association with hemiplegia and the presence of factor V Leiden.