Perinidal dilated capillary networks in cerebral arteriovenous malformations

OBJECTIVE: The perinidal vascular structures of cerebral arteriovenous malformations were examined, to clarify their pathomorphological features. METHODS: Twenty-two resected specimens of human brain structures adjacent to the nidus were examined. The vessels surrounding the nidus were three-dimensionally reconstructed with a computer graphics system. RESULTS: In all cases, the analysis of serial sections revealed that perinidal dilated capillaries were located in brain tissue 1 to 7 mm from the nidal border. The vessels surrounding the nidus demonstrated markedly dilated capillary networks (perinidal dilated capillary network PDCN]). The diameters of the vessels forming the PDCN were 10 to 25 times those of normal capillaries. The PDCN connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to the normal capillary network, arterioles, and venules. CONCLUSION: Without exception, each nidus was accompanied by a PDCN, which connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to normal capillaries, arterioles, and venules. The PDCN should be considered in studies aimed at gaining an understanding of the mechanisms underlying the intraoperative and postoperative bleeding, growth, and recurrence of surgically treated cerebral arteriovenous malformations.