Local Decrease of Pressure Pain Threshold in Nummular Headache

BACKGROUND: Nummular headache (NH) is a primary disorder presenting with localized pain that is circumscribed to a coin-shaped area of the head surface. METHODS: In 12 patients with NH (3 men and 9 women, 21 to 67 years old), we measured the pressure pain threshold (PPT) in several points while they were headache-free. The following cephalic and extracephalic points were explored: the symptomatic cranial area, a symmetrical point on the nonsymptomatic side, and 3 standardized pairs of symmetrical points (anterior part of the temporal muscle, upper trapezius muscle, and distal dorsal part of the second finger). Three consecutive PPT readings were obtained with an algometer on each point, and the repeatability of these measurements was always high (ICC: 0.93 to 0.97). RESULTS: Mean PPT was lower in the symptomatic cranial area than in the contra-lateral symmetrical point (1.8 +/- 0.6 kg/cm(2) vs 2.4 +/- 0.6 kg/cm(2); P < .001), whereas in the remaining reference points PPT was almost equal on both sides. CONCLUSIONS: According to these data, NH seems to be associated with a local increase of pain sensitivity to mechanical stimulation.