Brain cavernoma: a dynamic lesion.

BACKGROUND: Although the prevalence of brain cavernomas is high (0.50%), for unknown reasons, only a few of them display aggressive clinical behavior.
METHODS: From a personal series of 65 operated and histopathologically verified cavernomas, we have conducted a long-term study, both retrospectively and prospectively, of the main features that cause some cavernomas to be dynamic lesions.
RESULTS: Hemorrhage is the most common phenomenon. Extralesional bleeding due to the rupture of peripheral caverns is most often observed. These are never as immediately devastating as hemorrhages originating from a high-flow, high-pressure AVM. Extralesional hemorrhages tend toward spontaneous resorption, but the risk of recurrence exists and may lead to permanent disability or death (especially when the lesion is located in the brain stem). Intralesional bleeding caused by rupture of contiguous caverns is less frequently observed. This may lead to the formation of large cysts. Calcifications are mostly observed in patients presenting with chronic epilepsy. The bleeding risk of calcified cavernomas is low, but it can exist and should be taken into account in the surgical decision making. The growth of the cavernomatous matrix was obvious in three large cavernomas (two with calcification). No bleeding was found inside the lesions, suggesting a pure "intrinsic" growth. The role of pathologic angiogenic factors is highly probable in these cases. "De novo" appearing lesions were observed in five cases (four belonging to familial forms) on the magnetic resonance imaging survey of operated patients. Perilesional atrophy was observed in three cases (two operated) in patients with a long-lasting evolution. It suggests that the brain metabolism can be disturbed by slow, chronic effusion of blood around the cavernoma.
CONCLUSIONS: The dynamism of cavernomas is determined by extrinsic factors, mainly hemorrhage (with its own consequences); and by intrinsic factors: the pseudotumoral growth of the cavernous matrix. Therefore, when they are symptomatic, cavernomas should be totally removed.