Congenital stenosis of the aqueduct of Sylvius transmitted in an autosomal recessive mode (5 cases in 2 families)

: The authors report 5 cases of congenital hydrocephalus due to isolated stenosis of the aqueduct of Sylvius. In the first three cases (2 brothers and 1 sister) ventriculograms showed apparent obstruction of the aqueduct. A valve shunting was necessary at 1 month of age in cases 1 and 2, at 3 years of age in case 3. In cases 4 and 5 (1 brother and 1 sister) ultrasonic prenatal diagnosis showed ventriculomegaly and pregnancies were interrupted respectively at 31 and 28 weeks of gestational age. The pedigree of the families suggests that the inheritance of this abnormality is autosomal recessive. Such an inheritance is very unusual and confirms the difficulty of genetic counseling facing the first occurrence of hydrocephalus with stenosis of the aqueduct of Sylvius in a family. The prenatal diagnosis is based on fetal ultrasonic examination and may be obtained late in the pregnancy leading to therapeutic and ethical tricky decisions.