Reversed Robin Hood Syndrome and Ischemic Stroke: Usefulness of Transcranial Doppler (TCD/TCCS) to Real-Time Monitoring

In the presence of cerebral autoregulation and intact vasomotor reserve, hypercapnia leads to vasodilation of the intracranial arteries allowing for greater cerebral perfusion. There is a positive association between the presence of hypercapnia and carotid occlusive disease or intracranial arterial stenosis. However, in some patients, a paradoxical response is noted in the intracranial vasculature distal to a stenosis or occlusion in response to hypercapnia, namely, a decrease in cerebral blood flow due to exhausted vasomotor reserve in the presence of normal vasodilation in the contralateral healthy vessels. This intracranial steal has been termed reversed Robin Hood phenomenon, wherein you “rob the poor,” that is, the side with the exhausted vasomotor reserve, to “feed the rich,” that is, increase the cerebral blood flow to the healthy side of the brain. This phenomenon, when leading to neurological symptoms and sequel, is defined by the term reversed Robin Hood syndrome. Determination of one’s vasomotor reactivity can be made using inhaled CO2, intravenous injection of acetazolamide, or most simply by calculating the breath-holding index.