Approximately 50% of patients have an identifiable trigger to NDPH. Stress may be a trigger in some patients. Infection, particularly viral, is often cited as a trigger. In one study, Epstein-Barr virus was implicated as an initiating culprit. Exposure to certain toxins may also precede the onset of NDPH. Surgical procedures have occasionally triggered the onset of NDPH. Head injury, even when mild, may be an initial event. Cervical trauma or other pathology, particularly in those who have thin necks with cervical hyper mobility, may initiate the onset of NDPH.
Several studies have evaluated long-term outcomes. One study revealed that, after two years with NDPH, about 25% of the patients were free of headache, and 66% had at least a 50% or greater reduction in headaches over time, while 15% remitted; median time to remission was 21 months. 8% had a cyclic form, with a relapsing-remitting pattern. A small study of children and adolescents discovered that 8 out of 28 patients were free of headache within one to two years, while most (20) continued to suffer long-term from head pain.
NDPH is an important category of headache, as it is often difficult to treat, and results in considerable disability. It is unique in that over 50% of patients have an identifiable trigger, although these range from infection to surgery to head trauma. We are beginning to identify the pathophysiology that leads to NDPH. Treatment of NDPH is scattershot and varied at present; further studies will undoubtedly lead to more effective therapies.