Aqueductal stenosis in X-linked hydrocephalus: a secondary phenomenon?

Two cases of x-linked hydrocephalus are reported. One underwent postmortem examination: serial sections of the brain stem failed to show stenosis of the aqueduct, the mean and minimal cross-sectional areas of which were normal. However, there were some morphological changes which were compatible with a mechanical compression of the brain stem. It is postulated that in the Bickers and Adams syndrome of x-linked hereditary hydrocephalus the primary defect is a communicating hydrocephalus leading usually, but not always, to aqueductal stenosis. The importance of electrophysiological investigations for the correct diagnosis of the characteristic clasped-thumb deformity is also indicated.