For some headache sufferers, the pain never goes away — for months, years, or even decades. Dr. Elizabeth Loder, chief of the division of headache and pain at Brigham and Women’s/Faulkner Hospital, estimated that about 5 percent of the patients she sees at her clinic have new daily persistent headache.

With new daily persistent headache, or NDPH, however, none of the migraine medications seems to work, even when prescribed at optimal doses. There’s no known cause such as a head injury, tumor, or seizure condition.

And, unlike the typical headache sufferer, those with NDPH can name the exact day when their headache began.

Dr. Todd Rozen, director of the Geisinger Headache Center in Wilkes-Barre, Pa. — who sees the most intractable cases — said most of the headaches are caused by an immune system malfunction or a neck problem due to hyperflexibility.

But Dr. Peter Goadsby, a neurologist at the University of California, San Francisco who’s an expert on NDPH, said it is a vague syndrome without defined causes, rather than a distinct diagnostic entity with clear-cut triggers and treatments.

snfoertmeyer wrote: Are these mystery headache sufferers adequately hydrated? This was my problem for decades.