Epidemiology of Slit Ventricle Syndrome in Children

Incidence and Prevalence

• Incidence varies by report: From 3–70% of children with shunts develop small ventricles on imaging.  In one review, 64% developed slit ventricles, but only 6.5% required surgery.  The true incidence varies from practice to practice and in accordance with the shunt burden on that practice (2-4).
• Only some patients are symptomatic: On average, the clinical syndrome of debilitating headaches and small, unchanged ventricles complicates 1–37% of shunt procedures (8).
• Etiology of headaches differs: Headaches can be due to overdrainage or plateau waves. They can also be unrelated to the shunt’s function. Some have found that the majority are due to overdrainage (1), while others have found a more even distribution of causes for the headaches (18). The clinical presentation of overdrainage appears to be more common than an elevated ICP presentation.

Age Distribution

• 5 years after shunting: Most children become symptomatic on average 3–6 years after shunt placement during infancy.

Sex Predilection

• None: No apparent sex predilection. Any child with a shunt is at risk.

Geographic Distribution

• No known variance based on geographic distribution

Risk Factors

• Shunt insertion during infancy: Patients who received shunts as infants or early in life with open fontanelles seem predisposed to develop slit ventricle syndrome later in life. 
• Etiology of hydrocephalus: Any child with a shunt can develop slit ventricle syndrome. In one review (2), etiologies of hydrocephalus such as trauma, infection, and aqueductal stenosis carried higher incidences. 
• Type of shunt valve: The type of valve placed is another predictor of slit-like ventricles (Orbis-Sigma valve lower risk that differential pressure valves) but not necessarily clinical slit ventricle syndrome (8).
• Activity and dehydration: High levels of activity and dehydration can be related to overdrainage symptoms.

Relationships to Other Disease States and Syndromes

• Craniofacial syndromes: Children with shunts who have craniofacial syndromes can develop elevated ICP from cephalocranial disproportion and inadequate venous outflow. 
• Venous thrombosis: Any disease entity, congenital or acquired, that causes venous thrombosis or reduction in venous return can increase the risk of developing elevated ICP. In theory, this could link pseudotumor with slit ventricle syndrome in that lack of adequate venous outflow contributes to increases in ICP (6).