Primary Normal Pressure Hydrocephalus
Many normal pressure hydrocephalus (NPH) diagnoses are considered idiopathic, which means that the cause is unknown. These are also referred to as primary NPH.
Secondary Normal Pressure Hydrocephalus
When NPH results from a known cause it is referred to as secondary NPH. Secondary NPH can be diagnosed as the result of a head injury, cranial surgery, subarachnoid hemorrhage, tumor or cysts, as well as subdural hematomas, bleeding during surgery, meningitis and other brain infections.