Solitary Cysticercal Cyst Inside the Blake's Pouch Remnant of Mega Cisterna Magna with Associated Aqueductal Stenosis: Clinical and Management Implications

Abstract

Background: Intraventricular and subarachnoid forms represent the relatively complex, albeit uncommon, manifestations of central nervous system involvement by cysticercal cysts. Cysticercal encystation inside the Blake's pouch remnant of mega cisterna magna (MCM) remains an extremely rare clinical scenario that, to the best of our knowledge, has not been reported previously.

Case presentation: A 12-year-old boy presented with acute worsening and subsequent spontaneous resolution of his compensated hydrocephalus. Neuroimaging revealed features consistent with a MCM with septum inside, indicating remnants of the embryologic fourth ventricular diverticulum, the Blake's pouch. It also revealed a free-floating intact cysticercal cyst inside the MCM limited by the septum with aqueductal stenosis. The spontaneous clinicoradiologic resolution of hydrocephalus raised the possibility of ball valve obstruction of the cerebrospinal fluid outflow, i.e., Bruns syndrome. We successfully treated this patient with endoscopic extraction of the viable cysticercal cyst through a suboccipital burrhole.

Conclusions: The clinical scenario presented here has not been described previously. Endoscopic cyst removal in such a situation is an effective and low-risk procedure that obviates the further need for antihelminthic medications.

Keywords: Aqueductal stenosis; Blake's pouch; Endoscopic removal; Intraventricular cysticercosis; Mega cisterna magna; Neurocysticercosis; Posterior fossa cyst.