Angiographically hidden (diagnosis by MRI)
Well defined lesions comprised of vascular channels (neither arteries nor veins), and with no contribution to the brain parenchyma. It is like a vascular haematoma. It may calcify.
Usually a chance finding, but may bleed (20%) (less common than other vascular pathologies), and may cause epileptic seizures (60%).
The only treatment is surgical.
Two types: sporadic and hereditary. Some hereditary cases are Family Cavernomatosis and usually multiple.
The majority are located supratentorially, 20-23% in posterior fossa (predilection for the protuberance).