The meninges, bones, and skin over the cranial vault are normal. Results of neonatal neurologic examination are usually abnormal, but findings are subtle. The infant fails to develop normally. Externally, the head appears normal, but when transilluminated, light shines completely through. CT or ultrasound confirms the diagnosis.
Treatment is supportive, with shunting if head growth is excessive.
Hydrocephalus, ventricular enlargement with excessive CSF, is the most common cause of abnormally large heads in newborns. Hydrocephalus may be communicating or noncommunicating. Noncommunicating hydrocephalus indicates blockage at a site within the ventricular system or between it and the subarachnoid space. CT shows the ventricular size and possibly the site of obstruction. Ultrasound can define the degree of ventricular dilation, and serial studies can document progression of the hydrocephalus.