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Neuroradiology Case of the Week

Case 224

Uchendu Azodo, MD, Sudhir Kathuria, MD, and Henry Wang, MD, PhD

Clinical Presentation: Neonate with large head circumference.

Imaging Findings: Initial CT demonstrates massive distention of the ventricles with thinning of the cortical mantle (Fig.1). Subsequent MR imaging demonstrates same, with persistence despite shunt placement (Figs. 2&3).

Diagnosis: Congenital obstructive hydrocephalus

Discussion: Hydrocephalus can be congenital or acquired. The two forms are considered communicating or obstructive. This refers to whether or not there is a barrier to CSF flow. A difficult aspect in older patients is the fact that normal pressure hydrocephalus (NPH) occurs with ventricular dilation and no obstructing lesion. This is to be distinguished from communicating hydrocephalus in which there is frank overproduction of CSF that overwhelms the resorptive capacity of the ventricular system.
     This patient’s massive hydrocephalus was discovered soon after birth and was felt to be the obstructive and congenital type secondary to aqueductal stenosis. This has persisted despite shunt placement. The differential includes hydranencephaly and holoprosencephaly. Cortical mantle and presence of midline structures respectively (arrow and arrowhead, Fig. 3) help distinguish them.

References:

1. Neuroradiology Requisites, 2nd Ed., p.371-379.
2. http://www.healthline.com/galecontent/hydrocephalus-1
3. http://www.nlm.nih.gov/medlineplus/ency/article/001571.htm#Definition