Which of the following are potential causes of hydrocephalus?

• A. Overproduction of CSF
• B. Failure of absorption of CSF
• C. Obstruction in the normal flow of CSF
• D. All of the above

Answer: (D)

Hydrocephalus occurs when CSF builds up because production, flow, and absorption are out of balance. Any of these factors can cause the problem, so all of the mechanisms listed can contribute.

Overproduction of CSF happens if the choroid plexus makes CSF excessively, which can push more fluid into the ventricles (though this is relatively rare and typically seen in specific tumors like choroid plexus papilloma).

Obstruction in the normal flow of CSF creates a blockage that prevents CSF from moving freely through the ventricular system or into the subarachnoid space. This causes upstream dilation—often called noncommunicating hydrocephalus—because CSF backs up behind the obstruction.

Failure of absorption occurs when CSF cannot be reabsorbed properly, such as with scarring or dysfunction of the arachnoid granulations after infections or hemorrhage. This leads to a communicating form of hydrocephalus, with ventricles enlarging as CSF accumulates.

In practice, a patient can have more than one mechanism at once, so the most accurate answer is that all of these are potential causes.