I just read an article about the Tour De France winner:
(AP News) “Like cancer survivor Lance Armstrong, Alberto Contador has rebounded from a brush with death. After persistent headaches, Contador fell in the first stage of the 2004 Vuelta a Asturias race, went to hospital and learned he had a congenital cerebral vascular disorder, cavernoma. Eight months after the surgery, he won the fifth stage of the 2005 Tour Down Under. Today the only reminder of that scare is a large scar running down the side of his head”.
Here is part of an article about Cavernomas:
A Cavernoma is also known as a cavernous haemangioma. It is a congenital and usually a non-hereditary cavernous vascular malformation of a vein situated in the brain or spinal cord. In contrast to the AVM (arteriovenous malformation) the blood flow in the cavernoma is low. As the walls of the cavernoma are weak, blood slowly seeps out into the surrounding tissue.
A cavernoma may vary in size from one millimetre to a couple of centimetres. Thanks to the more generalised use of magnetic imaging, cavernomas are now diagnosed more frequently than before. Due to their low blood flow these malformations are not visible on angiograms. Cavernomas develop inconspicuously, and it is estimated that about half a percent of the population have cavernomas in their central nervous system. The majority of cavernomas are detected at the age of 20 to 40 years on the basis of the following symptoms: headache, epileptic fit, neurological deficiency such as weakness of the limbs, or generally a small, but sometimes massive, haemorrhage.
The risk of a cavernoma bleeding is about 1-2 % over the years. The haemorrhage from of a cavernoma is usually clearly smaller than for example that of an aneurysm or an arteriovenous malformation (AVM). Cavernomas situated in the brainstem or the cerebellum tend to bleed more easily and cause more damage than those found in the cerebrum.