RESUMO
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.
Assuntos
Malformações Arteriovenosas/patologia , Malformações Arteriovenosas/cirurgia , Neoplasias Encefálicas/cirurgia , Hemangioma Cavernoso do Sistema Nervoso Central/cirurgia , Radiocirurgia/efeitos adversos , Malformações Arteriovenosas/ultraestrutura , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/ultraestrutura , Relação Dose-Resposta à Radiação , Hemangioma Cavernoso do Sistema Nervoso Central/patologia , Hemangioma Cavernoso do Sistema Nervoso Central/ultraestrutura , Humanos , Estudos Longitudinais , Microscopia Eletrônica de Transmissão/métodos , Músculo Liso Vascular/patologia , Músculo Liso Vascular/cirurgia , Músculo Liso Vascular/ultraestruturaRESUMO
Knowledge of the structure and function of the central canal of the human spinal cord is important in understanding the pathogenesis of syringomyelia. Analysis of the morphology of the central canal is difficult using isolated histological sections. A 3-dimensional reconstruction technique using digitised histological sections was therefore developed to visualise the morphology of the central canal. The technique was used to study the canal in the conus medullaris and filum terminale of 1 sheep and 4 human spinal cords. A variety of morphological features were demonstrated including canal duplication, a terminal ventricle and openings from the canal lumen into the subarachnoid space. The findings suggest the possibility of a functionally important fluid communication in the caudal spinal cord which may have a sink function.
