[Diagnosis of Arnold-Chiari deformity in the newborn infant]

Meningomyelocele patients with Arnold-Chiari deformity type II have a great number of complex malformations of the brain that can be diagnosed quickly, safely and--last but not least--at low cost via sonography. Follow-up or control examinations of the changing ventricle size before and after shunt operation can be repeated any number of times without radiation exposure. Determination of the circumference of the head does not seem to be very helpful in deciding whether a ventricular enlargement makes shunting imperative or not. Prognostically of greater value seems to be the determination of the angle between the clivus and the fourth ventricle, values around 40 degrees (SD 35 degrees-46 degrees) being normal, whereas angles around 30 degrees are indicative of growing hydrocephalus.