CT cisternography in so-called external hydrochephalus in children

External hydrocephalus is described as widening of subarachnoid spaces in children with macrocrania. CT cisternography in 64 children under 2 years of age with enlarging head and CT diagnosis of pericerebral effusion was performed and compared with nonenhanced CT. CT showed the following: group 1, subdural type (n = 34) pericerebral effusions with cortical sulci compression; group 2, external hydrocephalus type (n = 30) pericerebral effusions with enlarged cortical sulci. CT cisternography showed no opacification of the pericerebral effusion. The authors conclude that even in typical cases of so-called external hydrocephalus, the subarachnoid spaces are never enlarged and the effusion is subdural