WATER-HAMMERING EFFECT - A PARTICULAR MEC HANISM OF HYDROCEPHALUS

Backround and purpose. - Aneurysms of the basilar artery can cause hyd rocephalus due to compression of the third ventricle or the sylvian aq ueduct. The observation of a particular case led to discuss another po ssible mechanism of hydrocephalus. Clinical presentation and radiologi cal studies. - An aneurysm of the basilar artery was revealed by an is chemic stroke in a 65-year-old man. Hydrocephalus developed during the following months. The MRI studies showed that it could not be explain ed merely by a permanent compression. However, the patient improved cl early after a ventriculo-peritoneal derivation. Conclusion. - The hydr ocephalus could be explained by a '' water-hammering '' effect due to the pulsating blood in the ectatic vessel, which created a cerebrospin al fluid outflow impairment through the third ventricle.