Symptomatic cyst of the septum pellucidum.

The presentation and management of a patient with symptomatic hydrocephalus from a cyst of the septum pellucidum is described and the underlying pathophysiology in relation to treatment is considered. The cyst appeared to cause intermittent obstruction of the foramina of Munro according to the degree of ventricular dilatation. Drainage and collapse of the cyst by fenestration reestablished continuous drainage of the ventricles with immediate symptomatic relief.