Shunt freedom in slit ventricle syndrome: using paradoxical ventriculomegaly following lumbar shunting to our advantage. Illustrative cases

BACKGROUND: The authors present two cases of paradoxical ventriculomegaly after lumboperitoneal (LP) shunting in patients with slit ventricle syndrome (SVS). OBSERVATIONS: After placement of an LP shunt, both patients rapidly developed radiographic and clinically symptomatic ventricular enlargement. The then generous ventricular corridors allowed both patients to be treated by endoscopic third ventriculostomy (ETV) with concurrent removal of their LP shunt. The patients then underwent staged increases in their shunt resistance to the maximum setting and remain asymptomatic. LESSONS: The authors suggest that this paradoxical ventriculomegaly may have resulted from a pressure gradient between the shunt systems in the intra- and extraventricular spaces due to a noncommunicating etiology of their hydrocephalus. ETV may successfully exploit this newfound obstructive hydrocephalus and provide resolution of the radiographic and clinical hydrocephalus through allowing for improved communication between the cranial and lumbar cerebrospinal fluid spaces in SVS.