What is the term we use for post meningitis hydrocephalus Like obstructive hydrocephalus
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The textbooks confirm exactly this. Here is a clear explanation:
Post-Meningitis Hydrocephalus = Communicating Hydrocephalus
The correct term is communicating hydrocephalus (also called non-obstructive hydrocephalus).
Why "communicating"?
In meningitis, the purulent/inflammatory exudate blocks the arachnoid granulations (the sites where CSF is reabsorbed into the venous sinuses). Because the obstruction is at the level of absorption - not within the ventricular pathways - CSF can still flow freely from the ventricles into the subarachnoid space. The ventricular system remains in continuity (i.e., "communicates") with the subarachnoid space.
- Result: the entire ventricular system dilates (lateral + 3rd + 4th ventricles)
- Cause: impaired CSF reabsorption, not blockage of flow within the brain
Contrast with Obstructive (Non-Communicating) Hydrocephalus
| Feature | Communicating | Obstructive (Non-communicating) |
|---|---|---|
| Site of blockage | Arachnoid granulations / basal cisterns | Within ventricular system (e.g., aqueduct of Sylvius) |
| Ventricular communication | Intact | Disrupted |
| Common causes | Meningitis, SAH, TB meningitis | Tumor, aqueductal stenosis, intraventricular hemorrhage |
| Ventricles affected | All ventricles dilate | Upstream ventricles dilate |
Note on TB Meningitis specifically
According to Grainger & Allison's Diagnostic Radiology, TB meningitis causes communicating hydrocephalus in 50% of adults and 85% of children due to the meningeal exudate obstructing CSF resorption. Less commonly, it can also cause non-communicating hydrocephalus if the exudate blocks the aqueduct or foramina.
So the short answer: post-meningitis hydrocephalus = communicating hydrocephalus, because the block is at reabsorption (arachnoid granulations), not at CSF flow.
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