During the sixteen years since Dandy1 introduced the method of substituting air for fluid in the ventricular and subarachnoid pathways in taking encephalograms, increasing importance has been attached to the value of this procedure for the diagnosis of certain diseases of the brain.
Originally used for the study of hydrocephalic conditions, the method has been extended to the study of fixed lesions of the brain in children in cases in which there are indeterminate symptoms and signs.2 The successful delineation of obscure intracranial pathologic changes by this method and the relative safety of the procedure explain why it is used in many clinics. The mortality in experienced hands is less than 1 per cent.
One of the common neurologic conditions encountered in the pediatric clinic of the University Hospital is some type of chronic lesion of the brain expressed in mental and physical retardation. This group of lesions,