Previously used term:
Pain of highly variable duration, but often chronic, in a small circumscribed area of the scalp in the absence of any underlying structural lesion.
A. Continuous or intermittent head pain fulfilling criterion B
B. Felt exclusively in an area of the scalp, with all of the following four characteristics:
2. fixed in size and shape
3. round or elliptical
4. 1-6 cm in diameter
C. Not better accounted for by another ICHD-3 diagnosis.
The painful area may be localized in any part of the scalp, but is usually in the parietal region. Rarely, 4.8 Nummular headache is bi- or multifocal, each symptomatic area retaining all the characteristics of nummular headache. Pain intensity is generally mild to moderate, but occasionally severe. Superimposed on the background pain, spontaneous or triggered exacerbations may occur. Duration is highly variable: in up to 75% of published cases, the disorder has been chronic (present for longer than three months), but cases have also been described with durations of seconds, minutes, hours or days.
The affected area commonly shows variable combinations of hypaesthesia, dysaesthesia, paraesthesia, allodynia and/or tenderness.
Other causes, in particular structural and dermatologic lesions, must be excluded by history, physical examination and appropriate investigations.