Hydrocephalus in children.

Imaging of hydrocephalus in utero, in infants and children is critically dependent on an understanding of the pathophysiology and treatment options for this condition in this age spectrum. For this reason, this chapter deals not only with the imaging modalities used to study hydrocephalus and how they are applied but also reviews key aspects of the pathophysiology and treatment of hydrocephalus in children. Imaging techniques to establish the diagnosis of chronic hydrocephalus fall into two categories: (1) tracer-type techniques that require an injection and observation of the transit of an injected substance through the ventricular system or subarachnoid space and (2) cross-sectional imaging, which allows for direct visualization of a point of obstruction within the ventricular system or subarachnoid space. For cross-sectional imaging, both magnetic resonance imaging (MRI) and computed tomography can be used, but MRI is usually preferred. Nomenclature has obscured the description of imaging findings in hydrocephalus. We suggest that most hydrocephalus is obstructive and propose to designate ventriculomegaly, the condition in which the ventricles are large on imaging, but there is no true obstruction to the outflow of cerebrospinal fluid.