✓ This study reports six cases of hydrocephalic children with the “slit ventricle syndrome” who evidenced reexpansion of the ventricular system following insertion of high-resistance valves and anti-siphon devices. The authors contend that slit ventricles and subsequent ventricular coaptation can be prevented by elimination or early replacement of low-resistance valves, and maintenance of normal- or nearly normalsized ventricles by shunt revision with valve upgrade and/or an anti-siphon device, as judged by the appearance of the ventricles on computerized tomography.