Experimental hydrocephalus Darko Lavrencic, MED zasebna splosna ambulanta 7 May 2014 I have a comment in regard to the following statement in the article: “However, the novel concepts are also challenged mainly by the lack of validated supporting data. For example, Klarica et al. failed to reproduce the historical experiments of Dandy, since no circulation of CSF was found along a plastic cannula introduced into the aqueduct of cats.«In the article by Dandy and Blackfan, which you cite, it is said »a piece of cotton in a small gelatin capsule … into the aqueduct of Sylvius, where it is deposited. «In the article by Oreskovic, Klarica and Vukic ( here I would like to point out the correct order of authors as opposed to “Klarica, Oreskovic and Vukic” used in the article), which you cite, it is said “A plastic cannula was introduced into the aqueduct of Sylvius through the vermis cerebelli and the outflow of CSF from the cannula was used as the CSF formation and circulation index” (also described in other similar articles by the above authors).Dandy and Blackfan blocked CSF flow in the aqueduct of Sylvius, while Oreskovic, Klarica and Vukic allowed CSF flow in the aqueduct of Sylvius through cannula. Can we assume that both experimental methods are the same?If the release of freshly actively formatted CSF happens during diastole when brain and choroid plexus shrink and create relative negative pressure in brain ventricles, this could explain hydrocephalus in Dandy and Blackfan experiment. For the comment on Oreskovic, Klarica and Vukic experiment, please see my on-line comment (Lavrencic 2013).References:Lavrencic, D. D. (2013). "During which phase of cardiac cycle is freshly actively formatted (FAF) cerebrospinal fluid (CSF) released into the brain ventricles: systole or diastole?". Retrieved 30 April 2013, from http://www.med-lavrencic.si/download/Lavrencic_CSF_release_cardiac_cycle.pdf Competing interests The author declares that no conflict of interest exists.