Symptomatic Progressive Ventriculomegaly in Hydrocephalics with Patent Shunts and Antisiphon Devices
The antisiphon device (ASD) was designed to prevent excessive negative intracranial pressure and overdrainage with cerebrospinal fluid shunts. It is used for prevention of slit ventricles and extreme shunt dependency. The author used the device in 40 children and young adults selectively for the treatment of shunt-produced low pressure headaches or prophylactically for patients judged to be at risk for development of subdural hematomas because of extreme hydrocephalus, fixed head size or tall stature. In 9 of these patients adverse symptoms occurred in spite of shunt patency. Four case reports describe patients 9, 15, 23, and 27 years of age who actually deteriorated after conversion to shunts incorporating ASD’s. Typically, deterioration occurred after the patient assumed an erect position. With patients in the horizontal position shunt patency was documented (Figure), but computed tomography revealed progressive ventriculomegaly when they were kept erect. Their symptoms disappeared and ventricular size diminished after conversion to proximal medium pressure diaphragm or spring-ball valve systems without ASD’s.