Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Paroxysmal Hemicrania ?
    ### Response:
    Paroxysmal hemicrania is a rare form of headache that usually begins in adulthood. Patients experience severe throbbing, claw-like, or boring pain usually on one side of the face; in, around, or behind the eye; and occasionally reaching to the back of the neck.
    