Cryptic arteriovenous and venous hamartomas of the brain.

In any large series of cases of spontaneous cerebral haemorrhage there are some of obscure aetiology that have certain clinical features in common. They occur in the younger age-groups, and although the onset of symptoms may be sudden, loss of consciousness is often delayed or incomplete. The cause of the bleeding often remains obscure on clinical examination and full investigation. Before the catastrophe the patient's condition has given no hint of any latent cerebral lesion. Although ultimate anatomical examination may reveal a vascular anomaly, the responsible lesion may be difficult to locate both on account of its situation and small size. For these reasons we propose the name " cryptic " for the series to be described. The incidence of these cryptic hamartomas in a total necropsy series of 461 examples of spontaneous intracranial haemorrhage, with a brief morphological account, has been published by one of us (Russell, 1954).