Pressure pain sensitivity of the scalp in patients with nummular headache: a cartographic study.

Nummular headache (NH) is characterized by focal pain fixed within a small round or elliptical area of the head surface. Sensory dysfunction is apparently restricted to the symptomatic area, but a thorough analysis of cranial pain sensitivity has not been performed. Pressure pain sensitivity maps were constructed for 21 patients with NH and 21 matched healthy controls. In each subject pressure pain thresholds (PPT) were measured on 21 points distributed over the scalp. In each patient PPT were also measured in the symptomatic area and at a non-symptomatic symmetrical point. In both groups an anterior to posterior gradient was found on each side, with no significant differences of PPT measurements between sides or groups. In patients with NH, only the symptomatic area showed a local decrease of PPT (significant in comparison with the non-symptomatic symmetrical point, P < 0.001). These findings further support that NH is a non-generalized disorder with a peripheral source.