Is there a link between pain chronification, and allodynia and vitamin D deficiency in headache?

Objective: The vitamin D deficit has been associated to pain chronification, and chronic migraine is frequently associated with allodynia. The aim of this study was to assess the potential role of VitD in pain chronification and its relation to the occurrence of allodynia. Methods: We recruited 76 consecutive patients: 32 belonged to the episodic migraine (EM), 34 to the chronic migraine and medication overuse (CM-MOH) groups and 10 to the tension-type headache (TTH) group. All patients underwent neurological and physical examination and anamnestic data collection including allodynia and serum calcifediol (25(OH)D) assessment. Results: The occurrence of patients with vit D deficit was significantly higher in the CM-MOH (46%), than in the EM groups (25.7%) and in the TTH group (11.4%). The Vit D deficit was not significantly associated with any of the other variables. Allodynia also was more frequent in CM-MOH (66.7%) than in the EM (29.2%) and TTH groups (6.7%). On the contrary the occurrence of allodynia was independent from the vit D deficit (allodynia occurred in 42.4% of patients with and 57.6% without vit D deficit) Conclusion: Prevalence of VitD deficiency and allodynia were significantly higher in patients suffering from CM-MOH, however the co-occurrence of allodynia and VitD deficiency were not correlated, thus suggesting that chronification and allodynia do not stem from the same pathophysiological mechanism.