Proliferation Activity Is Significantly Elevated in Partially Embolized Cerebral Arteriovenous Malformations

Background: The natural history of cerebral arteriovenous malformations (AVMs) is yet to be determined. It has been shown that angiogenic factors are involved in the pathogenesis of AVMs, in particular in partially embolized lesions. This study was conducted to investigate the expression of angiogenic and proliferative factors in relation to different clinical conditions and treatment modalities. Methods: Immunohistochemistry was performed for 145 consecutive cases of cerebral AVMs. The specimens were stained with antibodies against VEGF, bFGF, Ki 67, CD 34 and CD 31. Expression was correlated with clinical presentation (haemorrhage, seizures or other symptoms), AVM localization, size, eloquence and venous drainage, as well as with preoperative AVM embolization. Results: Whereas no correlation was found between the expression of angiogenic factors and different clinical conditions, we observed a significantly increased proliferation activity as shown by Ki 67 expression in patients with intracerebral haemorrhage (p = 0.02) and in patients with preoperative embolization (p = 0.02). Conclusions: Increased proliferation activity in partially embolized AVMs supports a ‘no-touch’ strategy and clinical observation in high-risk AVMs and demands complete AVM elimination in treatable lesions.