ENDOSCOPIC OBSERVATION OF A SLIT-VALVE MECHANISM IN A SUPRASELLAR PREPONTINE ARACHNOID CYST - CASE-REPORT

OBJECTIVE AND IMPORTANCE: There are several theories regarding the gen esis of arachnoid cysts. However, controversy continues over what mech anisms are involved in the formation of the cysts. CLINICAL PRESENTATI ON: A 6-year-old female patient presented with precocious puberty. The results of a neurological examination were unremarkable. Magnetic res onance imaging revealed a large suprasellar prepontine arachnoid cyst. INTERVENTION: An endoscopic ventriculocystostomy via a right frontal burr hole was performed. During inspection of the cyst, we clearly obs erved a slit-valve mechanism that was obviously responsible for the fo rmation and enlargement of the cyst. The valve was formed by an arachn oid membrane surrounding the basilar artery. Synchronous with pulsatio n, the valve opened and closed rapidly. CONCLUSION: A slit-valve mecha nism seems to be at least one factor of the genesis of suprasellar pre pontine arachnoid cysts.