Endoscopic fenestration of symptomatic septum pellucidum cysts: Three case reports with discussion on the approaches and technique

Objectives: We describe three patients with symptomatic septum pellucidum cysts treated by endoscopic fenestration and discuss the different endoscopic approaches to these cysts. Clinical presentation: The patients are an 8-year-old boy, a 7-year-old boy and a 21-year-old woman; this last also had a right frontal cavernous angioma and a pituitary microadenoma. All patients presented with headache, associated with vomiting in two and behavioral changes in one. In all cases magnetic resonance showed a septum pellucidum cyst. Intervention: Two patients were operated upon by posterior approach through a right occipital burr hole and underwent fenestration from the right occipital horn to the cyst, with a second fenestration from the cyst to the left lateral ventricle in one. Another patient underwent microsurgical removal of a right frontal cavernoma and endoscopic cyst fenestration with both lateral ventricles through a right frontal craniotomy. Postoperatively, headache and vomiting resolved in all cases and behaviour changes improved in one. Conclusions: Endoscopic fenestration is the treatment of choice for septum pellucidum cysts, where it results in immediate relief of the mass effect of the cyst and in the remission of the associated symptoms. We suggest a posterior approach through a right occipital burr hole. It allows one to easily cannulate the occipital horn, which is usually larger than the frontal one, thus avoiding the risk of damaging the vascular and neural structures surrounding the foramen of Monro. Besides, the endoscopic trajectory is in our opinion more direct. The two-window technique, with fenestration of the cyst into both lateral ventricles, improves the chances of long-term patency.