Thank you for your interesting comments outlining the sufficiency of collagen-fleece sealing for ventricular defects after carmustine wafer implantation. The use of fibrinogen-coated collagen fleeces for sealing and reconstructive procedures of ventricular defects in neurosurgery has not yet been analysed by randomised clinical trials, but their use for neurosurgical indication as a local hemostatic agent with potent prevention of cerebrospinal fluid fistula has been reported in the literature, e.g. Nistor et al. (Skull Base Surg 7:23-30, 1997). We used the fleece for several complex hemostatic and dural-reconstructive indications, including cerebral as well as spinal operative procedures. The sponge-like consistency allows comfortable and accurate modelling, with a fast adhesive effect after direct fluid contact. We share the opinion of the authors that well-designed studies are needed to analyse the potential benefit of using this agent for different neurosurgical indications compared with other biomaterials for reconstructive and watertight sealing strategies.