Post-haermorrhagic hydrocephalus (which is the communicating
type) is caused when the outlets for csf reabsorption are blocked or damaged by bleeding within the subarachnoid space (the space between the skull and pia matter layer of the meninges) or within the ventircles of the brain. Blood acts as an irritant to the meninges and damages them or leads them to stick together. This means they are no longer able to reabsorb csf, therefore causing hydro. My
hydrocephalus, caused my meningitis is also communicating because meningitis has similar effects to a haemorrhage. The meninges are damaged by the infection, and can no longer perform their function of reabsorbing csf.
Does that make sense?