Fig. 7
From: Endoscopic management of periventricular and intraventricular arachnoid cysts
a MRI T1 axial sequence with contrast showing posterior fossa cyst related to the fourth ventricle and compressing it. b Endoscopic view showing identification of the fourth ventricular wall from inside the cyst and performing endoscopic cystoventriculostomy. c Applying a fenestration between the cyst and the ventricle with a Fogarty catheter. d Endoscopic navigation inside the fourth ventricle with identification of the aqueduct of Sylvius