Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Porencephaly ?
    ### Response:
    Porencephaly is a rare condition that affects the central nervous system. People with porencephaly develop fluid-filled cysts or cavities in the brain either before or shortly after birth. The severity of the condition and the associated signs and symptoms vary significantly based on the size, location, and number of cysts.
    