Hemorrhagic stroke, cerebral amyloid angiopathy, Down syndrome and the Boston criteria. 
A stroke, or a cerebrovascular accident (CVA) is a life-threatening condition which often results in permanent or significant disability in the adult population.  Several classifications of CVAs exist, one of them being based on the mechanism of injury of brain tissue: ischemic (85-90%) and hemorrhagic (10-15%).  In a hemorrhagic stroke an intercranial bleeding occurs, leading to the formation of a focal hematoma typically located in the basal ganglia of the brain (approx.  45% of cases).  A common yet underestimated cause of intracerebral hemorrhage is cerebral small vessel disease with microhemorrhages, including the cerebral amyloid angiopathy (CAA).  This condition is associated with the deposition of amyloid-beta in arterial walls (in soft meninges, subcortical areas and the cerebral cortex).  Research has shown that causes of hemorrhagic changes in the brain include genetic disorders, such as Down syndrome.  The association is caused by the so-called 'gene dosage effect', as the gene for the precursor protein for amyloid-beta is located in chromosome 21.  We wish to present the case of a 60 year old patient with Down syndrome who suffered a hemorrhagic stroke without antecedent hypertension.  Based on the history taken, diagnostic imaging and the source literature, a diagnosis of cerebral amyloid angiopathy as the source of the bleeding was made (however it must be noted that without a full post-mortem examination, the Boston criteria allow only for a 'probable cerebral amyloid angiopathy' diagnosis to be made).  The authors hereby also report the need to modify the Boston criteria for cerebral amyloid angiopathy.