Page 119 - The clinical aspects and management of chronic migraine Judith Anne Pijpers

CGRP release may mediate central sensitisation, thus leading to allodynia 6,16,29–31 Therefore, we expect that allodynia may also be a predictor of response to CRGP(- receptor) monoclonal antibody treatment in chronic migraine.
The association between cutaneous allodynia, and its spatial distribution, and response to treatment may have additional value for current pathophysiological concepts on migraine chronification.The predictive value for failure on treatment was most pronounced for extracephalic allodynia, which is considered indicative for thalamic involvement 6–8. Therefore, we hypothesize that especially thalamic involvement will be a predictor for unresponsiveness to treatment in chronic migraine patients. Until now, cutaneous allodynia has mainly been studied as a predictor of response to acute treatment with triptans or non-migraine specific acute pain medication, yielding contradictory results. Some studies suggest that patients are unresponsive to triptans once cutaneous allodynia has manifested 32,33, others suggest a preserved triptan response despite of cutaneous allodynia 34,35 although the distinction between ipsi- and contra-lateral cephalic and/or extracephalic allodynia is not always made. Nonetheless, this has led to the hypothesis that response to triptans may be indicative for different underlying sensitization mechanisms 7,8,34,36. As triptans act both peripherally and post- synaptic on second order neurons, but not on third order neurons, we can hypothesize that triptan-response would cease upon thalamic involvement.
In our study, mechanical allodynia was associated with change in monthly migraine days, as opposed to thermal allodynia. This finding would suggest that mainly mechanoreceptors, such as the low threshold Aβ fibres and C-type mechanorecepters 13,36,37 may be involved in migraine chronification. Although thermal allodynia is present in migraineurs as well during attacks, and in lesser extent in between attacks 7,38, heat pain thresholds were not related to headache frequency 38, supporting our findings. This also fits with our conclusion that the predictive association was only present for migraine-related outcomes and not for headache days in general. In line with other studies, this suggests that central sensitization is more pronounced in migraine and not in other types of headaches 12. Concordantly, a recent study investigating the ability to trigger cutaneous allodynia after nitroglycerine provocation, did not find an association between headache frequency and the occurrence of allodynia after nitroglycerine 34, whereas migraine frequency and occurrence of (spontaneous) cutaneous allodynia during migraine are shown to be related 10.
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Allodynia as predictor for treatment response
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