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Obstructive hydrocephalus can be further divided into
communicating
and noncommunicating
hydrocephalus. Communicating hydrocephalus is more common than
non-communicating hydrocephalus, and results from a
blockage outside of the ventricular system. The ventricular fluid is in
communication with the subarachnoid space. Most often this occurs at the
arachnoid villi where the CSF is normally absorbed (see figure above - red
circle). Examples of communicating hydrocephalus include post-meningitic
or post-hemorrhagic hydrocephalus. Any process that scars the subarachnoid space
can lead to communicating hydrocephalus.
Non-communicating hydrocephalus results from obstruction with the
ventricular system, preventing
communication with the subarachnoid space (see figure above - blue circles). Examples of non-communicating
hydrocephalus include aqueductal stenosis or ventricular tumors that obstruct
the ventricles (e.g. pineal tumors that block the aqueduct) and trap the CSF
made proximal to the obstruction. |
