Dynamic mechanical (brush) allodynia in cluster headache

OBJECTIVE: To examine the occurrence of dynamic mechanical (brush) allodynia (BA) in patients with cluster headache (CH). BACKGROUND: Cutaneous allodynia was described in migraine. It was related to sensitization of neurons in the trigeminal nucleus caudalis (TNC). This phenomenon has not been previously described in cluster headache. METHODS: We examined adult patients with episodic or chronic CH for the presence of BA. Demographic data and the characteristics of CH were obtained through a questionnaire. Allodynia testing was performed by repetitively applying a 4x4-inch gauze pad to skin areas in the trigeminal and cervical dermatomes. Degree of allodynia was measured on a 100-mm visual analog scale (VAS). The relations between the location and severity of headache and allodynia were assessed. RESULTS: Ten patients (all male, mean age 39.3) were included in the study. Seven had episodic CH (ECH) and 3 had chronic CH (CCH). Two patients were in acute attack when tested for BA. In total, 4 (40%) of the 10 patients had BA (2 [28.6%] of the 7 with ECH and 2 [66.7%] of the 3 with CCH). Median disease duration was 22 years for patients with BA and 12 years for patients without BA. Of the two patients in acute attack, one had BA, ipsilateral to the headache, which was reduced 20 minutes after treatment, along with reduced headache severity. CONCLUSIONS: This is the first report on the occurrence of cutaneous allodynia in CH. The presence of BA in CH may be related to CH type (episodic vs. chronic) and to the duration of disease. These results support the concept that allodynia in CH may result from a time-dependent process of neuronal sensitization.