There was a rosary like chain of T2/FLAIR hyper intensities in the centrum semiovale. Other apparently random patches in the parieto-occipital and frontal regions didn't show any enhancement to suggest a brain access. These areas showed restricted diffusion as well.
They asked me to have a look. This apparently random pattern started making sense when I delved deeper into antecedents. This child had been in severe catecholamine resistant shock and required 3 ionotropes.
This pattern is classical of water-shed infarcts. Parts of the brain which lie in the borders zone of major non-anastomosing arteries such as the anterior and middle cerebral artery or the middle and posterior cerebral artery are vulnerable during prolonged periods of hypotension.
There is another hypothesis which still is not completely proven. Besides hypo perfusion, there may be an additional role of micro emboli which are not cleared in these areas of sluggish flow. These infarcts have been seen in patients with severe occlusive disease of he internal carotid artery which can throw emboli as well as cause hypo perfusion. Cardiac and aortic disease too can result in this deadly combination of emboli and hypo perfusion.
There are two types of watershed infarcts. The external or cortical are described in the areas bordering the major arteries - anterior, middle or posterior cerebral arteries. These small wedge shaped infarcts recover well probably due to leptomeningeal or dural collaterals.
Conversely the internal or subcortical borderzone infarcts lie at the borders of smaller arteries like the lenticulostriate and middle cerebral artery and involve the subcortical white matter. These are more ominous and do not do so well in the long term probably because they lack the collateral support from other arterial systems.
If you live on the edge, its social support that bails you out during a crisis.
