Dynamic mechanical (brush) allodynia in cluster headache: a prevalence study in a tertiary headache clinic.

Cutaneous allodynia (CA) has been described in migraine and has been related to treatment failure. There are little data about the incidence of CA in other primary headache syndromes such as cluster headache (CH). The objectives of this study are to evaluate the prevalence of dynamic mechanical (brush) allodynia (BA) in CH patients attending a tertiary headache clinic, and to assess its relation to disease characteristics. Adult patients with episodic or chronic CH were recruited. We obtained demographic data and data on disease characteristics through a structured questionnaire, and tested the patients for brush allodynia BA by applying a 4 x 4 gauze pad over the V1, C2/C3 and C8 skin areas bilaterally. The prevalence of allodynia in the entire study population and in the different sub-groups was calculated. We also examined the association between CA and demographic parameters, and its association with disease characteristics. Forty-one patients were recruited (22 men, 19 women; mean age 44.9 years). Twenty-two had chronic CH (CCH) and 19 had episodic CH (ECH). Mean disease duration was 14.1 years (12.3 the CCH group and 15.7 in the ECH group). Overall, 20 (49%) patients were allodynic. There was no statistically significant association between the presence of allodynia and age, gender, diagnosis (episodic vs. chronic CH), disease duration or disease severity. In conclusion, BA was common in this CH patient sample. The therapeutic implications of the presence of BA in CH need to be further studied.