Diagnosis
Although NDPH is classified as a primary headache syndrome, it must be remembered that a number of important conditions can present with a new-onset persisting headache, and these must be excluded prior to making a diagnosis of a primary headache disorder.The diagnosis is one of excluding the many secondary types or NDPH mimics, which is especially critical early in the course of the disease when a secondary etiology is more likely. NDPH mimics include but are not limited to:
neoplasms
subarachnoid hemorrhage
idiopathic intracranial hypertension
temporal arteritis
chronic subdural hematoma
post-traumatic headaches
sphenoid sinusitis
hypertension
spontaneous cerebrospinal fluid leak
cervical artery dissections
pseudotumor cerebri without papilledema
cerebral venous thrombosis
Chiari malformation
NDPH with medication overuse headacheMany doctors state that the condition is best viewed as a syndrome rather than a diagnosis. Once a diagnosis of NDPH is made, clinicians argue that patients are best managed according to the more detailed pathophysiology-based diagnosis than lumped together into a single group, since a single disorder is unlikely to exist.NDPH is classified as a Primary Headache Disorder by the ICHD-2 classification system (by the IHS) using number 4.8. It is one of the types of primary headache syndromes that present as a chronic daily headache, which is a headache present for more than 15 days a month for more than 3 months.
This exclusion due to migrainous features could have adverse scientific, diagnostic, and treatment consequences.One proposal for reclassification of the criteria is from a study conducted on retrospective analysis of the records of 1348 patients regularly treated at the headache clinic of the Department of Neurology of Santa Casa de São Paulo, Brazil, and would be the following subdivision: NDPH with migraine features and without migraine features that would allow the inclusion of all individuals present who has a daily and persistent headache from the beginning.Another proposed reclassification of the criteria is from a study conducted as a retrospective chart review of patients seen at the Headache Center at Montefiore Medical Center in Bronx, New York, from September 2005 to April 2009. The revised criteria for NDPH definition does not exclude migraine features (NDPH-R), and three subdivisions were created and described based on prognosis: Persisting, remitting, and relapsing–remitting. Additionally, this revised criteria would not include parts C or D currently required by the ICHD diagnostic criteria for NDPH. Pathophysiology
The pathophysiology of NDPH is poorly understood. Research points to an immune-mediated, inflammatory process. Cervical joint hypermobility and defective internal jugular venous drainage have also been suggested as causes.In 1987, Vanast first suggested autoimmune disorder with a persistent viral trigger for CDH (now referred to as NDPH). Post-infectious origins have been approximated to make up anywhere between 30 and 80% of NDPH patients in different studies.