Neurology and the blood: haematological abnormalities in ischaemic stroke.

Haematological disorders account for up to 8% of all ischaemic strokes in diVerent series. Table 1 shows the haematological disorders associated with ischaemic stroke. Most studies report them as being more common in younger stroke patients, particularly those who have undetermined stroke aetiology after extensive tests including full cardiac evaluation.Many primary haematological disorders have been associated with ischaemic stroke but in many patients with stroke other aetiological factors are also present making a cause and eVect relation diYcult to prove. Furthermore, some of these haematological factors, particularly deficiencies of natural anticoagulants, are more potent causes of venous thrombosis. Therefore in such cases paradoxical embolism from the venous system should be considered, and excluded, before arterial thrombosis is implicated.