A 2005 review suggested that most "sinus headaches" are migraines. The confusion occurs in part because migraine involves activation of the trigeminal nerves, which innervate both the sinus region and the meninges surrounding the brain. As a result, accurately determining the site from which the pain originates is difficult. People with migraines do not typically have the thick nasal discharge that is a common symptom of a sinus infection.
A 2005 ReviEw SuggesTeD thAt MOst "sinus HeaDAches" Are MigRaIneS. tHe cOnfusion occurs in PARt Because miGRaine inVoLvEs aCTivatIoN of THe triGEMiNal neRves, which Innervate bOtH The SiNus reGiOn anD thE Meninges surroUNdinG tHe bRain. aS A reSUlt, aCcuRaTely DeTerMiNing THE site from WhiCh ThE pain ORiginAteS Is diffICuLT. PEOPle with mIGrainES dO nOt TYpicaLlY havE the thICk nasal DiScHaRge that is A commOn sYMpTom Of a sinUs infEctioN.