This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous System, Subject name: Pediatrics
Which of the following is the most common cause of congenital hydrocephalus? 
Select and explain. 
A. Craniosynostosis, B. Intra uterine meningitis, C. Congenital aqueductal stenosis, D. Vein of Galen malformation
C: Congenital aqueductal stenosis
Answer: C: Congenital aqueductal stenosis 
Explanation: Ans. C. Congenital aqueductal stenosisObstructive or noncommunicating hydrocephalus develops most commonly in children because of an abnormality of the aqueduct of Sylvius (Congenital aqueductal stenosis) or a lesion in the fourth ventricle. Nonobstructive or communicating hydrocephalus most commonly follows a subarachnoid hemorrhage, which is usually a result of intraventricular hemorrhage in a premature infant. Among the various causes of meningitis, tuberculous meningitis has a propensity to cause hydrocephalus (due to thick, tenacious exudate that obstructs the basal cistern).