Headache caused by a chronic infectious or inflammatory disorder of the paranasal sinuses and associated with other symptoms and/or clinical signs of the disorder.
A. Any headache fulfilling criterion C
B. Clinical, nasal endoscopic and/or imaging evidence of current or past infection or other inflammatory process within the paranasal sinuses
C. Evidence of causation demonstrated by at least two of the following:
1. headache has developed in temporal relation to the onset of chronic rhinosinusitis
2. headache waxes and wanes in parallel with the degree of sinus congestion, drainage and other symptoms of chronic rhinosinusitis
3. headache is exacerbated by pressure applied over the paranasal sinuses
4. in the case of a unilateral rhinosinusitis, headache is localized ipsilateral to it
D. Not better accounted for by another ICHD-3 diagnosis.
It has been controversial whether or not chronic sinus pathology can produce persistent headache. Recent studies seem to support such causation.