Response to Letter by Yousaf et al

Response: We deeply appreciate the interest of Dr Yousaf and his colleagues in our study and we understand their concerns. Certainly, differences in vessel characteristics exist between species and vascular territories, especially when compared to human brain vessels. Therefore, care must be taken when comparing complication rates assessed by animal models to complication rates in humans. However, we encounter a large variety of vessel conditions even in humans during our daily work: from young and straight vessels to elongated, sclerotic and dilated vessels, from vessels prone to spasm (more often found in younger patients) to less reactive arteries.1,2 These different vessel …