Central Pain Modulation and Scalp Tenderness in Frequent Episodic Tension‐Type Headache

Abstract

To determine whether the inhibitory effect of acute limb pain on pain to mechanical stimulation of the forehead is compromised in individuals with frequent episodes of tension-type headache. Central pain modulation processes are disrupted in patients with chronic tension-type headache. This deficit in pain modulation might be a predisposing characteristic that increases vulnerability to tension-type headache and to symptoms such as scalp tenderness, or could be a feature that develops secondarily during attacks and that persists for a few days afterward. To distinguish between these 2 possibilities in the present study, inhibitory pain control was investigated in participants with episodic rather than chronic tension-type headache. Pressure-pain thresholds and sensitivity to sharpness in the forehead were measured in 34 individuals with 1-10 episodes of tension-type headache per month and in 32 controls before and after immersion of their hand in painfully cold water. Before the cold pressor test, pressure-pain thresholds and sensitivity to the sharp stimulus were similar in both groups. Mild headache developed and pressure-pain thresholds in the forehead decreased from 631 ± 178 g to 579 ± 196 g (mean ± SD) after the cold water immersion in the episodic tension-type headache group (P < .05). However, sharpness ratings did not change (mean rating 3.2 ± 1.4 on a 0-10 scale). In contrast, headache did not develop, pressure-pain thresholds did not change, and sharpness ratings decreased from 3.0 ± 1.3 to 2.3 ± 1.1 after the immersion in controls (P < .01). These findings suggest that endogenous pain modulation processes are compromised in individuals with frequent episodic tension-type headache. This deficit could increase vulnerability to scalp tenderness and recurrent episodes of headache.