Persistent daily headaches begin without warning and occur continuously for 3 months or longer. The most prominent feature of this type of headache is that the patient remembers the circumstances of the headache, sometimes the exact date and time of the first headache.

Headaches not only affect the patient's life, but also cause physical weakness and dangerous complications. There are two types of headaches caused by changes in pressure inside the skull: Headaches caused by decreased intracranial pressure (spontaneous intracranial hypotension, or SIH) and headaches caused by increased intracranial pressure (idiopathic intracranial hypertension, or IIH).