Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Hemicrania Continua ?
    ### Response:
    Hemicrania continua is a chronic and persistent form of headache marked by continuous pain that varies in severity, always occurs on the same side of the face and head, and is superimposed with additional debilitating symptoms. on the continuous but fluctuating pain are occasional attacks of more severe pain.
    