Core Terms & Classification
Communicating hydrocephalus
Communicating hydrocephalus is a type in which cerebrospinal fluid can still flow out of the ventricles but is not properly absorbed or circulated beyond them.
In short: Communicating hydrocephalus
- The ventricles still "communicate" with the subarachnoid space.
- The problem is usually with CSF absorption or flow over the brain's surface.
- Causes include hemorrhage, infection, and others.
- It contrasts with obstructive (non-communicating) hydrocephalus.
What it is
Communicating hydrocephalus is a type in which CSF flows normally out of the ventricular system but is not adequately absorbed or circulated once it reaches the spaces around the brain. The ventricles remain connected ("communicating") to the subarachnoid space.
Understanding Communicating hydrocephalus
In this form, the blockage is not within the ventricles themselves but typically at the level of CSF absorption (for example, at the arachnoid granulations) or in the flow of fluid over the surface of the brain. Common causes include bleeding into the CSF (such as after subarachnoid or intraventricular hemorrhage) and infection (such as meningitis), which can impair absorption. This classification — communicating versus non-communicating — dates back to early descriptions of hydrocephalus and remains useful, though CSF dynamics are now understood to be more complex.
Why it matters
Understanding the communicating type helps families see that the problem lies in absorption or circulation rather than a physical blockage inside the ventricles. This distinction influences which treatments are most suitable.
Common questions
What does "communicating" mean here?
The ventricles still connect to the spaces around the brain.
Where is the problem?
Usually with CSF absorption or flow over the brain's surface.
What causes it?
Often hemorrhage or infection, among other causes.
Bottom line
Communicating hydrocephalus is a type where CSF flows out of the ventricles but is not properly absorbed or circulated, often after hemorrhage or infection.
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