Investigators from four European tertiary care hospitals (in Paris, France; Milan, Udine and Perugia, Italy) performed a case-control study of children and adolescents aged 6 to 17 years diagnosed with primary headaches in the emergency department by a pediatric neurologist using the validated ICHD-3 criteria. They enrolled 648 controls and 424 cases (257 patients with migraine and 167 with tension-type headache). Investigators masked to a patient’s group allocation diagnosed functional gastrointestinal disorders using the Rome III diagnostic criteria. Eighty-three (32%) children and adolescents in the migraine group were diagnosed with functional gastrointestinal disorders compared with 118 (18%) in the control group (p<0·0001). Multivariable logistic regression showed a significant association between migraine and three gastrointestinal disorders: functional dyspepsia, irritable bowel syndrome and abdominal migraine. The authors concluded that correct recognition would have an impact on the diagnosis and therapeutic management of these pediatric gastrointestinal disorders. 
COMMENTARY. This well conducted multicenter trial included all functional gastrointestinal disorders defined according to ROME III criteria. However, among digestive afflictions, celiac disease (CD) deserves particular attention. CD patients may exhibit a myriad of extra-intestinal symptoms, which includes neurological symptoms such as migraine. Studies report a high frequency of migraines in patients with CD and vice versa, and describe the beneficial effect of a gluten-free diet in these cases . Also, the prevalence of CD among children with irritable bowel syndrome (IBS) is reported to be 4 times higher than among the general pediatric population . Using the Rome III diagnostic criteria of functional gastrointestinal disorders would help to distinguish CD from the broad pool of IBS, with a potential consequent relief of migraine upon initiation of the appropriate diet.
On the other hand, recent findings regarding the role of the gastrointestinal microbiota in the gut-brain axis suggests that an unbalanced gut flora (i.e. dysbiosis) can be associated with neurological diseases like migraine. Enhanced pro-inflammatory immune responses have been reported with intestinal disorders associated with dysbiosis and increased intestinal permeability (just like IBS and celiac disease) as well as in migraine patients . Evidence suggests that alterations in gut microbiota could be a potent mediator in migraine ; this might explain, at least partly, the current study results. We are, definitely, what we eat!