The widened frontal subarachnoid space. A CT comparative study between macrocephalic, microcephalic, and normocephalic infants and children.

The computed tomographic scans of the heads of 67 infants and children with frontal subarachnoid space widening seen during a 5-year period were retrospectively studied. Only 22.3% of patients had macrocephaly. Comparison of the clinical and radiologic characteristics of subarachnoid widening in macrocephalic children and in normocephalic or microcephalic children showed no significant differences. It is concluded that undue emphasis has been laid on the association between this radiologic sign and macrocephaly. Widening of the subarachnoid space in children may be a variation of normal development of brain whereby there is a transient accumulation of cerebrospinal fluid in the frontal region. The term "external hydrocephalus" may therefore be inappropriate in the absence of significant ventricular widening and clinical signs of raised intracranial pressure.