Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Normal Pressure Hydrocephalus ?
    ### Response:
    Normal pressure hydrocephalus (NPH) is an abnormal buildup of cerebrospinal fluid (CSF) in the brain's ventricles, or cavities. It occurs if the normal flow of CSF throughout the brain and spinal cord is blocked in some way. This causes the ventricles to enlarge, putting pressure on the brain.
    