Different responses of cavernous malformations and arteriovenous malformations to radiosurgery.

The vascular structure of cavernous malformations (CMs) and arteriovenous malformations (AVMs) is different and they have differing clinical responses to radiosurgery. The structural differences of irradiated and non-irradiated CMs and AVMs were examined to clarify their differential responses to radiosurgery. CMs showed a greater ratio of intraluminal diameter to vessel wall thickness and a lack of subendothelial fibroblasts, myofibroblasts and smooth muscle cells compared with AVMs. Partial proteinaceous clots (19-22% of lumen) formed in CM sinusoids after radiosurgery but complete vaso-occlusion did not occur for up to 6 years after radiosurgery. In contrast, complete vaso-occlusion (91-98% of lumen) by fibrin thrombi that are permanent clots was observed in AVM vessels. Radiation-induced neuronal loss, neurofibrillary degeneration of neurons and myelin fragmentation were typical in the surrounding brain tissue of the irradiated lesions. The different structure and cellular composition of CMs and AVMs is likely to influence their responses to radiosurgery.

[Histopathology of central nervous system cavernomas]. / Anatomie pathologique des cavernomes du système nerveux central.

Central nervous system cavernomas are vascular malformations, which occur in two circumstances: sporadic forms and familial autosomal dominant forms. The lesion consists of enlarged, closely packed vessels without interposition of brain parenchyma, surrounded by hemosiderin and gliosis, calcified in few cases. In 80% of sporadic forms the lesion is unique, multiple lesions are rare (median: 4). In familial forms the lesions are always multiple. Cavernomas are often associated with other vascular malformations, especially with venous developmental anomalies. The size of cavernomas is variable from 1 mm to several centimeters. About 70% of cases are supratentorial and 30% in the posterior fossa, particularly in the brain stem. Macroscopic and histopathological findings are typical and the diagnostic is generally easy.

[Intracranial cavernous angiomas: ultrastructural and immunochemical study]. / Vnutricherepnye kavernoznye angiomy: ul'trastrukturnoe i immunogistokhimicheskoe issledovanie.

43 brain cavernous angiomas (CA) were clinically and morphologically studied. The presence of smooth muscles and endotheliocytes in the trabeculae was confirmed. The sources of blood supply and the nature of medullary changes at the CA periphery were clarified. The hypothesis of CA hormonal dependence has been rejected.