The 67-year-old female patient complained of headaches and left homonymous hemianopsia. MR imaging revealed a large, space-occupying intraparenchymal cyst lying behind the right posterior horn. On the sagittal images a thin parenchymal bridge which separates the cyst from the posterior horn could be seen. Since the cyst was symptomatic and, in the follow-ups, was seen to be growing progressively, endoscopic cyst fenestration was indicated.