Page 108 - The clinical aspects and management of chronic migraine Judith Anne Pijpers

Chapter 6
Abstract
Objective Central sensitisation is an important mechanism in migraine chronification. It is presumed to occur in second and third order neurons sequentially, resulting in an analogous spatial distribution of cutaneous allodynia with cephalic and extracephalic symptoms. We investigated whether allodynia, and its subtypes based on spatial distribution and type of stimulus, predict response to treatment in chronic migraine patients.
Methods This study was conducted as part of the CHARM study (NTR3440), a randomized, double-blind, placebo-controlled trial in chronic migraine patients with medication overuse to assess whether therapy with Botulinum toxin A enhances efficacy of withdrawal. We included 173 patients, aged 18-65 years. The presence of cutaneous allodynia at baseline was established with the Allodynia Symptom Checklist, and subdivided in i) spatial distribution and ii) type of stimulus. Primary endpoint was reversion from chronic to episodic migraine. Results Of all patients, 129 (74.6%) reported cutaneous allodynia. Absence of allodynia was predictive for good outcome compared to presence of allodynia, as the odds ratio of reversion from chronic to episodic migraine was 2.45 (95%CI: 1.03-5.84, p=0.042). The predictive value was more pronounced when subdivided for spatial distribution, with odds ratios of 4.16 (95%CI: 1.21-14.30, p=0.003) and 7.32 (95%CI: 1.98- 27.11, p=0.024) for participants without allodynia versus cephalic and extracephalic allodynia respectively. Mechanical allodynia, but not thermal allodynia, was associated with outcome. Similar predictive associations were found for other migraine specific outcome measures.
Interpretation Cutaneous allodynia, an important marker for central sensitization, has predictive value for treatment response in chronic migraine.
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