Ventricular wall granulations and draining of cerebrospinal fluid in chronic giant hydrocephalus.

BACKGROUND In rare cases, adults with normal or almost normal cognition may have giant brain ventricles surrounded by a sliver of brain. Because the usual flow of cerebrospinal fluid (CSF) is interrupted in these individuals, they may develop alternative CSF pathways to preserve brain function. OBJECTIVE To describe novel morphologic autopsy findings in a patient with chronic giant hydrocephalus that suggest the existence of alternative CSF draining pathways. DESIGN Case report. SETTING Autopsy study. PATIENT A 48-year-old man with chronic compensated hydrocephalus associated with a Dandy-Walker malformation. MAIN OUTCOME MEASURE Autopsy findings. RESULTS We observed microscopic structures on the ventricular wall that may facilitate CSF resorption. Their histologic appearance, reminiscent of pacchionian granulations, showed the opposite relation in regard to CSF/blood compartments: whereas the core of a pacchionian granulation contains CSF and the granulation is bathed in blood of the venous sinus, the core of the ventricular granulation in our patient contained venules, with the granulation bathed in ventricular CSF. CONCLUSIONS These previously unreported (to our knowledge) ventricular wall granulations may facilitate draining of CSF into the venous system when CSF outflow from the ventricular system is occluded. The presence of these ventricular structures illustrates biologic adaptation to anomalous conditions and successful compensation.